Research & Evidence

Executive Summary

Body composition—the ratio of fat mass to lean mass—is distinct from body weight. Understanding the science of muscle protein synthesis (MPS), fat metabolism, and the rate limits of body composition change helps athletes set realistic expectations and optimize their approach. Body recomposition (simultaneous fat loss and muscle gain) is possible under specific circumstances, but most athletes should pursue sequential phases of focused fat loss or muscle gain.

Deep Dive

Muscle Protein Synthesis (MPS)

The Anabolic Process

Muscle growth occurs when muscle protein synthesis exceeds muscle protein breakdown over time:

Net muscle balance = MPS - MPB

For hypertrophy, this balance must be positive consistently over weeks and months.

mTORC1: The Master Regulator

mTORC1 (mechanistic target of rapamycin complex 1) is the key regulator of MPS:

Activators:

• •Amino acids (especially leucine)
• •Insulin
• •Mechanical tension (resistance exercise)
• •IGF-1

Inhibitors:

• •AMPK (activated by energy deficit, endurance exercise)
• •Rapamycin (research tool)
• •Low amino acid availability

The Leucine Threshold

Leucine is the key amino acid that triggers MPS:

Practical implication: Each protein feeding should contain ~2-3g leucine (found in ~20-40g high-quality protein).

The Refractory Period

After MPS is stimulated, there's a "refractory period" where the same stimulus has diminished effect:

• •MPS elevation lasts ~3-5 hours post-meal
• •Full sensitivity returns after ~4-6 hours
• •This is why protein distribution matters

Optimal distribution: 4-5 protein feedings of 0.4-0.55g/kg each, spaced 3-5 hours apart.

Protein Dose-Response

Exception: After whole-body resistance training, higher doses (40g) may be beneficial.

Muscle Protein Breakdown (MPB)

MPB is the catabolism of muscle proteins, regulated by:

Ubiquitin-Proteasome System:

• •Main pathway for muscle protein degradation
• •Activated by fasting, cortisol, immobilization
• •Tags proteins with ubiquitin for destruction

Autophagy:

• •Cellular "recycling" process
• •Important for removing damaged proteins
• •Activated by fasting, exercise

Factors increasing MPB:

• •Caloric deficit
• •Low protein intake
• •Cortisol (stress, inadequate sleep)
• •Inactivity
• •Inflammation

Factors decreasing MPB:

• •Adequate protein intake
• •Resistance exercise
• •Insulin (from feeding)
• •Adequate sleep

Fat Metabolism and Lipolysis

Adipose Tissue Function

Adipose tissue stores energy as triglycerides and releases fatty acids through lipolysis:

Hormonal regulation:

• •Catecholamines (adrenaline, noradrenaline): Activate lipolysis
• •Insulin: Potently inhibits lipolysis
• •Cortisol: Increases lipolysis (chronically)
• •Growth hormone: Increases lipolysis

Key insight: High insulin levels (from carbohydrate intake) suppress fat release. This doesn't prevent fat loss if in caloric deficit, but it affects the timing of fat oxidation.

Regional Fat Loss ("Spot Reduction")

Can you lose fat from specific areas?

Short answer: Minimally, if at all.

Evidence:

• •Exercise does not preferentially burn fat from worked muscles
• •Fat loss follows genetic patterns
• •"Stubborn" areas (lower body in women, abdomen in men) lose fat last
• •Overall caloric deficit is what matters, not specific exercises

What you can do:

• •Reduce overall body fat percentage
• •Accept that genetics determine pattern
• •Be patient; stubborn areas come off eventually

Rate Limits of Body Composition Change

Maximum Fat Loss Rate

Why not faster? Excessive deficits lead to:

• •Greater muscle loss
• •Hormonal disruption
• •Metabolic adaptation
• •Adherence problems
• •Increased injury risk

Maximum Muscle Gain Rate

Realistic monthly muscle gain (under optimal conditions):

Important: These are maximums under ideal conditions. Most people achieve less.

Factors affecting muscle gain rate:

• •Training status (beginners gain faster)
• •Genetics
• •Sleep quality
• •Caloric surplus
• •Protein intake
• •Training quality
• •Age
• •Hormonal status

Body Recomposition

Definition: Simultaneous fat loss and muscle gain

When Is Recomposition Possible?

The Energy Partition Theory

The body must decide how to allocate energy:

In caloric surplus:

• •Excess energy stored as fat AND/OR
• •Supports muscle protein synthesis

In caloric deficit:

• •Fat released for energy AND/OR
• •Muscle may be catabolized

At maintenance:

• •Neutral energy balance
• •Can shift body composition slowly

Recomposition Strategy

For those who can achieve recomposition:

Trade-off: Recomposition is slower than focused fat loss OR muscle gain. Most athletes are better served by sequential phases.

Body Composition Assessment Methods

Practical recommendation: Use the same method consistently to track trends, rather than obsessing over absolute numbers.

The Role of Hormones

Testosterone

• •Primary anabolic hormone in males
• •Promotes MPS, reduces MPB
• •Lower in caloric deficit
• •Sleep deprivation reduces levels

Cortisol

• •"Stress hormone"
• •Catabolic in chronic excess
• •Elevated by caloric deficit, poor sleep, excessive training
• •Some cortisol is necessary and normal

Insulin

• •Anabolic for muscle (promotes MPS, inhibits MPB)
• •Prevents fat release from adipose
• •Elevated after carbohydrate/protein intake
• •Not inherently bad; natural response to eating

Growth Hormone

• •Promotes lipolysis
• •May support MPS indirectly
• •Elevated during sleep, fasting, exercise
• •Supplements do not meaningfully increase it

Practical Framework: Cut vs. Bulk

Cutting (Fat Loss Phase):

• •Caloric deficit (500-750 kcal/day typical)
• •High protein (2.0-2.4 g/kg)
• •Maintain training intensity (reduce volume if needed)
• •Rate: 0.5-1% bodyweight/week
• •Duration: Until goal reached or deficit fatigue

Bulking (Muscle Gain Phase):

• •Caloric surplus (200-500 kcal/day)
• •High protein (1.6-2.0 g/kg)
• •Progressive overload in training
• •Rate: 0.5-1% bodyweight/month
• •Duration: Until desired size or fat gain excessive

Maintenance:

• •Calories at maintenance
• •Moderate protein (1.6-1.8 g/kg)
• •Maintain training
• •Duration: Between phases (4-8 weeks minimum)

Practical Takeaways

• •MPS is triggered by leucine: Need 2-3g leucine (20-40g protein) per meal
• •Distribute protein: 4-5 meals/day optimizes total MPS
• •Rate limits exist: You can't rush body composition change without consequences
• •Recomposition is slow: Most athletes should use focused cut/bulk phases
• •Spot reduction doesn't work: Fat loss follows genetic patterns
• •High protein during deficit: 2.0-2.4g/kg preserves muscle
• •Sleep matters: Hormonal optimization requires adequate sleep
• •Track trends, not absolutes: Body composition changes slowly

Common Mistakes

Evidence Quality: ★★★★☆

Well-established:

• •MPS regulation by mTORC1 and leucine
• •Protein dose-response for MPS
• •Muscle memory phenomenon
• •Rate limits of fat loss and muscle gain

Ongoing research:

• •Optimal recomposition protocols
• •Individual variation in response
• •Role of various supplements

Key References

• •Phillips SM. (2014). A brief review of higher dietary protein diets in weight loss. Journal of Nutrition. 144(6):S856-S860.
• •Morton RW, et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. British Journal of Sports Medicine. 52(6):376-384.
• •Helms ER, et al. (2014). Evidence-based recommendations for natural bodybuilding contest preparation. Journal of the International Society of Sports Nutrition. 11:20.
• •Trexler ET, et al. (2014). Metabolic adaptation to weight loss: implications for the athlete. Journal of the International Society of Sports Nutrition. 11:7.

Executive Summary

Diet is a primary modifiable risk factor for the leading causes of death and disability: cardiovascular disease, type 2 diabetes, cancer, and neurodegenerative disease. The evidence strongly supports plant-forward dietary patterns (Mediterranean, DASH) that emphasize whole foods while limiting processed foods, added sugars, and excessive saturated fat. No single "superfood" prevents disease—overall dietary pattern matters most.

Deep Dive

Cardiovascular Disease

Heart disease remains the #1 cause of death globally. Nutrition profoundly influences cardiovascular risk.

Key Risk Factors Modifiable by Diet

The Saturated Fat Debate: Current Consensus

What we know:

• •Saturated fat raises LDL cholesterol
• •LDL cholesterol drives atherosclerosis (causal relationship)
• •Replacing saturated fat with unsaturated fat reduces CVD risk
• •Replacing saturated fat with refined carbs is neutral or harmful

What's debated:

• •Whether saturated fat itself, or what it replaces, matters more
• •Dairy's unique role (may be less harmful than other saturated fat sources)
• •Individual variation in response

Practical guidance:

• •Limit, but don't fear, saturated fat
• •Choose unsaturated fats (olive oil, nuts, fish) as primary fat sources
• •Avoid replacing fat with refined carbs

LDL, ApoB, and Heart Disease

ApoB (apolipoprotein B) is emerging as the best marker:

• •Each atherogenic particle has one ApoB
• •Directly counts harmful particles
• •Better predictor than LDL-C

Dietary factors affecting ApoB/LDL:

• •Saturated fat (increases)
• •Trans fat (strongly increases)
• •Soluble fiber (decreases)
• •Plant sterols (decrease)
• •Weight loss (decreases)

The DASH and Mediterranean Diets

DASH (Dietary Approaches to Stop Hypertension):

• •Proven to lower blood pressure
• •Rich in fruits, vegetables, whole grains
• •Low-fat dairy
• •Limited sodium, red meat, added sugars
• •Reduces BP by 5-11 mmHg

Mediterranean diet:

• •Proven to reduce cardiovascular events (PREDIMED trial)
• •High in olive oil, nuts, fish
• •Moderate wine (optional)
• •Reduces CVD events by ~30%

Type 2 Diabetes Prevention and Management

Risk Factors

Dietary Strategies for Prevention

Weight loss is primary:

• •5-7% weight loss reduces diabetes risk by 58% (DPP trial)
• •Sustained caloric deficit of any type works

Beyond calories:

• •Fiber (particularly visceral fiber) improves insulin sensitivity
• •Whole grains associated with lower risk
• •Sugary beverages increase risk
• •Ultra-processed foods increase risk

Glycemic index/load:

• •Low-GI diets may help blood sugar control
• •Effect is modest; overall diet pattern matters more
• •Individual glycemic responses vary widely

For Those with Diabetes

Key insight: Multiple dietary patterns work. Adherence and sustainability matter most.

Cancer Prevention

Approximately 30-40% of cancers are preventable through lifestyle, with nutrition playing a significant role.

Strong Evidence

Moderate Evidence

What We Can't Claim

No specific food "cures" or "prevents" cancer.

"Superfoods" claims are overhyped:

• •Blueberries are healthy but won't cure cancer
• •Turmeric is fine but not a cancer treatment
• •Green tea is beneficial but not magic

Overall dietary pattern matters more than any single food.

Practical Cancer Prevention Diet

• •Maintain healthy body weight (most important)
• •Limit alcohol (ideally none; if drinking, limit to 1-2/day)
• •Limit processed meat (occasional is fine; daily is concerning)
• •Limit red meat (1-2x/week reasonable)
• •Eat plenty of fiber (25-38g daily)
• •Eat plenty of vegetables and fruits
• •Choose whole grains over refined
• •Avoid sugary drinks

Neurological Health and Cognitive Aging

Dietary Factors and Brain Health

MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay):

• •Hybrid of Mediterranean and DASH
• •Emphasizes brain-healthy foods
• •Associated with slower cognitive decline
• •May reduce Alzheimer's risk by 35-53%

MIND diet components:

• •Green leafy vegetables (daily)
• •Other vegetables (daily)
• •Berries (2x/week)
• •Nuts (daily)
• •Olive oil (primary fat)
• •Whole grains (3x/day)
• •Fish (1x/week)
• •Beans (every other day)
• •Poultry (2x/week)
• •Wine (1 glass/day, optional)

Foods to limit:

• •Red meat
• •Butter/margarine
• •Cheese
• •Pastries/sweets
• •Fried/fast food

Key Nutrients for Brain Health

What Doesn't Work (or Lacks Evidence)

• •High-dose antioxidant supplements (may be harmful)
• •"Brain supplements" (mostly unproven)
• •Coconut oil for Alzheimer's (no evidence)

Metabolic Syndrome

Definition: Cluster of conditions (high BP, high blood sugar, excess waist fat, abnormal lipids) that increase disease risk.

Dietary approach:

• •Weight loss (primary intervention)
• •Mediterranean or DASH pattern
• •Limit refined carbs and added sugars
• •Increase fiber
• •Choose healthy fats
• •Moderate alcohol

The Problem with "Superfoods"

Marketing vs. science:

• •"Superfood" is a marketing term, not a scientific category
• •No single food provides magical benefits
• •Dietary pattern matters, not individual foods
• •"Superfoods" are often just... good foods

Reality check:

• •Kale is healthy, but so is spinach, broccoli, and cabbage
• •Acai berries are fine, but so are blueberries (much cheaper)
• •Quinoa is good, but so is brown rice or oats

Practical Takeaways

• •Weight management is foundational: Obesity increases risk for most chronic diseases
• •Dietary pattern > individual foods: Mediterranean, DASH, and MIND diets have strong evidence
• •Limit processed meat: Strong cancer link; occasional OK, daily concerning
• •Moderate alcohol or none: No safe level for cancer; modest CVD benefit is controversial
• •Fiber is protective: 25-38g daily from varied sources
• •Whole foods over supplements: Nutrients work together in food matrix
• •Sustainability matters: The best diet is one you can maintain

Common Mistakes

Evidence Quality: ★★★★☆

Well-established:

• •Obesity increases disease risk
• •Mediterranean/DASH diets reduce cardiovascular disease
• •Fiber reduces colorectal cancer risk
• •Processed meat is carcinogenic
• •Alcohol increases cancer risk

Ongoing research:

• •Optimal macronutrient ratios
• •Role of specific polyphenols
• •Individual response variation
• •Gut microbiome's role

Key References

• •Estruch R, et al. (2018). Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. NEJM. 378(25):e34.
• •Knowler WC, et al. (2002). Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. NEJM. 346(6):393-403.
• •World Cancer Research Fund/AICR. (2018). Diet, Nutrition, Physical Activity and Cancer: a Global Perspective.
• •Morris MC, et al. (2015). MIND diet associated with reduced incidence of Alzheimer's disease. Alzheimer's & Dementia. 11(9):1007-1014.

Executive Summary

Energy balance—the relationship between calories consumed and calories expended—is the primary determinant of weight change. However, the "calories in, calories out" model is often oversimplified. Both sides of the equation are dynamic, influenced by diet composition, metabolic adaptation, hormones, and behavior. Understanding these nuances is essential for sustainable body composition management in athletes.

Deep Dive

The Energy Balance Equation

Weight change = Energy In - Energy Out

While mathematically simple, both sides of this equation are complex and interconnected.

Energy Expenditure Components

1. Basal Metabolic Rate (BMR) / Resting Metabolic Rate (RMR)

Definition: Energy required to maintain vital functions at rest.

Comprises: 60-75% of total daily energy expenditure (TDEE)

Determinants:

• •Fat-free mass (FFM): The primary driver; more muscle = higher BMR
• •Body size: Larger bodies require more energy
• •Age: Declines ~2-3% per decade after 20
• •Sex: Males typically have higher BMR (more FFM)
• •Genetics: Can vary 5-10% between similar individuals
• •Hormones: Thyroid (T3/T4), cortisol, testosterone influence BMR

Estimation equations:

• •Mifflin-St Jeor (most accurate for most adults):
• •Men: BMR = 10×weight(kg) + 6.25×height(cm) - 5×age + 5
• •Women: BMR = 10×weight(kg) + 6.25×height(cm) - 5×age - 161

2. Thermic Effect of Food (TEF)

Definition: Energy required to digest, absorb, and process nutrients.

Comprises: 5-10% of TDEE

Varies by macronutrient:

• •Protein: 20-30% of calories consumed
• •Carbohydrate: 5-10%
• •Fat: 0-3%
• •Alcohol: 10-30%

Practical implications:

• •High-protein diets have slightly higher TEF
• •Whole foods have higher TEF than processed (more work to digest)
• •Effect is real but modest; don't overestimate its impact

3. Exercise Activity Thermogenesis (EAT)

Definition: Energy expended during planned exercise.

Comprises: Highly variable; 5-30% of TDEE depending on activity level

Factors affecting exercise calorie burn:

• •Intensity and duration
• •Body weight (heavier = more calories for same activity)
• •Exercise efficiency (trained athletes are more efficient)
• •Afterburn (EPOC): Generally modest; highest after HIIT

4. Non-Exercise Activity Thermogenesis (NEAT)

Definition: Energy expended through all movement that isn't formal exercise.

Includes: Fidgeting, standing, walking, gesturing, maintaining posture

Comprises: 15-50% of TDEE; highly variable between individuals

Why NEAT matters:

• •Can vary by 2,000+ kcal/day between individuals
• •Decreases unconsciously during caloric deficit (body conserves energy)
• •Increases with overfeeding in some individuals
• •Explains much of individual variation in weight loss responses

SPA (Spontaneous Physical Activity): Some people unconsciously move more when overfed and less when underfed. This is partially genetic and helps explain "hardgainers" and those who resist weight gain.

Metabolic Adaptation

When you create a caloric deficit, the body adapts to conserve energy:

Mechanisms of Adaptation

1. 1.Reduced BMR

• •Beyond what's explained by weight loss
• •Thyroid hormone (T3) decreases
• •Sympathetic nervous system activity decreases

1. 1.Reduced NEAT

• •Unconscious reduction in movement
• •Often the largest contributor to adaptation
• •Can account for 200-400 kcal/day reduction

1. 1.Increased hunger hormones

• •Ghrelin (hunger hormone) increases
• •Leptin (satiety hormone) decreases
• •Makes adherence harder over time

1. 1.Improved exercise efficiency

• •Same exercise burns fewer calories
• •Modest effect but real

Magnitude of Adaptation

Research suggests metabolic adaptation can reduce expenditure by 5-15% beyond predicted losses. The "Biggest Loser" study showed contestants had metabolic rates 500+ kcal/day below predicted years later.

Key insight: The body "defends" its weight, making sustained weight loss challenging.

Strategies to Minimize Adaptation

• •Slower rate of loss: 0.5-1% bodyweight/week
• •Diet breaks: Periodic return to maintenance calories
• •Resistance training: Preserves muscle mass
• •High protein: Preserves muscle, higher TEF
• •NEAT awareness: Consciously maintain activity

Set Point vs. Settling Point Theory

Set Point Theory

The body has a genetically determined weight it "defends" through metabolic and behavioral changes. Evidence: weight regain after dieting, metabolic adaptation.

Settling Point Theory

Weight stabilizes where energy intake and expenditure balance, influenced by environment, behavior, and biology. More optimistic: weight can be changed by altering the environment.

Reality: Likely a combination. Biology creates a "comfortable range" but environment and behavior determine where within that range you settle.

Individual Variation in Energy Balance

Why do some people gain weight easily while others struggle?

1. 1.NEAT variability: Huge differences in unconscious movement
2. 2.Gut microbiome: Affects nutrient extraction efficiency
3. 3.Genetics: FTO gene and others influence appetite and metabolism
4. 4.Hormonal differences: Thyroid, cortisol, insulin sensitivity
5. 5.Muscle mass: Higher FFM = higher expenditure
6. 6.Sleep: Poor sleep increases hunger and decreases expenditure
7. 7.Stress: Cortisol affects appetite and fat storage

Energy Availability for Athletes

Energy availability (EA) = (Energy Intake - Exercise Energy Expenditure) / Fat-Free Mass

• •Optimal EA: 45+ kcal/kg FFM/day
• •Low EA: <30 kcal/kg FFM/day
• •Critically low: <25 kcal/kg FFM/day

Low EA leads to:

• •Hormonal disruption (amenorrhea, low testosterone)
• •Bone density loss
• •Impaired performance and recovery
• •Increased injury risk
• •Immune suppression

This is the basis of Relative Energy Deficiency in Sport (RED-S).

Calorie Counting Accuracy

Why Calorie Labels Are Imperfect

1. 1.FDA allows 20% error on nutrition labels
2. 2.Actual absorption varies: Cooking, processing, and gut bacteria affect extraction
3. 3.Fiber and resistant starch: May provide fewer usable calories
4. 4.Nuts: Often provide 15-25% fewer calories than listed (cell walls intact)

Tracking Accuracy

• •Most people underestimate intake by 20-50%
• •Portion estimation is poor without measuring
• •"Hidden" calories in cooking oils, sauces, etc.
• •Beverages and snacks often forgotten

Practical approach: Track for awareness, but don't obsess over exact numbers. Use body weight trends as the ultimate feedback.

Practical Takeaways

• •Calories matter most: For weight change, energy balance is primary
• •NEAT is underrated: Unconscious movement can vary by 1000s of calories
• •Adaptation is real: Your body fights weight loss; plan for it
• •Protein is protective: High protein preserves muscle and has higher TEF
• •Rate matters: Slower fat loss = better muscle preservation and less adaptation
• •Individual variation is huge: What works for one person may not work for another
• •Athletes: watch energy availability: Low EA harms health and performance
• •Use weight trends: 7-day averages are more reliable than daily fluctuations

Common Mistakes

Evidence Quality: ★★★★★

Well-established:

• •Energy balance determines weight change
• •Components of energy expenditure
• •Metabolic adaptation exists
• •NEAT variation between individuals

Emerging/uncertain:

• •Magnitude of adaptation and whether it persists
• •Optimal strategies to minimize adaptation
• •Role of gut microbiome in energy extraction

Key References

• •Hall KD, et al. (2012). Energy balance and its components: implications for body weight regulation. American Journal of Clinical Nutrition. 95(4):989-994.
• •Rosenbaum M, Leibel RL. (2010). Adaptive thermogenesis in humans. International Journal of Obesity. 34:S47-S55.
• •Fothergill E, et al. (2016). Persistent metabolic adaptation 6 years after "The Biggest Loser" competition. Obesity. 24(8):1612-1619.
• •Pontzer H, et al. (2016). Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans. Current Biology. 26(3):410-417.
• •Mountjoy M, et al. (2018). IOC consensus statement on relative energy deficiency in sport (RED-S). British Journal of Sports Medicine. 52(11):687-697.

Executive Summary

Most supplements don't work. A small number have robust evidence supporting their use in athletes. This guide separates science from marketing, providing evidence-based protocols for the supplements that actually enhance performance. Always prioritize diet fundamentals before considering supplements—they're the "cherry on top," not the foundation.

Deep Dive

Tier 1: Strong Evidence (★★★★★)

Creatine Monohydrate

What it is: A naturally occurring compound (synthesized from amino acids) stored primarily in muscle as phosphocreatine.

Mechanism:

• •Phosphocreatine rapidly regenerates ATP during high-intensity exercise
• •Increases phosphocreatine stores by 20-40%
• •Enhances ATP resynthesis between efforts

Benefits:

• •Increased strength and power output (5-15%)
• •Enhanced high-intensity exercise capacity
• •Improved recovery between sets and sessions
• •Increased lean mass (partially water, partially muscle)
• •Potential cognitive benefits

Dosing Protocol:

Form: Creatine monohydrate is the most researched and cost-effective. Fancy forms (HCL, buffered, etc.) offer no proven advantage.

Side effects:

• •Weight gain (1-3kg) due to water retention in muscle
• •Mild GI distress (take with food if needed)
• •No evidence of kidney damage in healthy individuals

Who benefits most:

• •Strength and power athletes
• •Repeated sprint sports
• •Vegetarians/vegans (lower baseline stores)

Who may not benefit:

• •Pure endurance athletes (minimal; added weight may be negative)
• •"Non-responders" (~20-30% of population)

Evidence rating: ★★★★★ (Hundreds of studies; most researched supplement ever)

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Caffeine

What it is: A central nervous system stimulant found in coffee, tea, and supplements.

Mechanism:

• •Blocks adenosine receptors (reduces fatigue perception)
• •Increases catecholamine release
• •Enhances fat oxidation
• •Reduces perceived exertion

Benefits:

• •Improved endurance performance (2-4% on average)
• •Enhanced high-intensity performance
• •Increased alertness and focus
• •Reduced perceived effort

Dosing Protocol:

Sources:

• •Coffee (~95mg per cup)
• •Caffeine pills (precise dosing)
• •Pre-workout supplements (check dose)
• •Caffeine gum (faster absorption)

Considerations:

• •Habituation: Regular users may need higher doses; consider tapering 3-7 days before competition
• •Sleep: Avoid within 6-8 hours of sleep (half-life ~5-6 hours)
• •Genetics: CYP1A2 gene affects metabolism; "slow metabolizers" may not benefit as much
• •Anxiety: Can worsen symptoms in susceptible individuals

Race day strategies:

1. 1.Full dose 60 min pre-race
2. 2.Half dose pre-race, half during (long events)
3. 3.Caffeine gum during for late boost

Evidence rating: ★★★★★ (Consistent, robust findings across hundreds of studies)

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Protein Supplementation

What it is: Concentrated protein from various sources (whey, casein, plant proteins).

Mechanism:

• •Provides amino acids for muscle protein synthesis
• •Convenient way to hit protein targets

Benefits:

• •Equivalent to food protein for muscle building
• •Convenient, portable, quick absorption (whey)
• •Can help athletes meet elevated protein needs

Types comparison:

Dosing:

• •20-40g per serving (0.4-0.55g/kg)
• •As needed to hit daily protein target (1.6-2.2g/kg for athletes)
• •Not inherently superior to whole food protein

Key insight: Protein powder is food, not a magic supplement. Use it for convenience, not because it's "better" than chicken or eggs.

Evidence rating: ★★★★★ (Protein works; powder is just a convenient form)

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Tier 2: Good Evidence (★★★★☆)

Beta-Alanine

What it is: An amino acid that increases muscle carnosine levels.

Mechanism:

• •Carnosine buffers hydrogen ions (H+) during high-intensity exercise
• •Delays fatigue in 1-10 minute efforts
• •Takes 4+ weeks to saturate muscle stores

Benefits:

• •Improved performance in efforts lasting 1-10 minutes
• •May benefit repeated sprint ability
• •Possible enhancement of training capacity

Dosing Protocol:

Side effect: Paraesthesia (tingling sensation) is harmless but uncomfortable. Splitting doses or using sustained-release reduces this.

Who benefits:

• •Middle-distance athletes (800m-3k)
• •Rowers, swimmers (200-400m events)
• •High-intensity repeated efforts

Who may not benefit:

• •Pure endurance athletes
• •Short sprinters (<60 second efforts)
• •Strength athletes (limited evidence)

Evidence rating: ★★★★☆ (Good evidence for specific applications)

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Nitrates (Beetroot Juice)

What it is: Dietary nitrates (NO3-) primarily from beetroot or leafy greens.

Mechanism:

• •Converted to nitric oxide (NO) via oral bacteria
• •Improves exercise efficiency (less O2 required)
• •Enhances blood flow and muscle contractile function

Benefits:

• •Improved endurance performance (1-3%)
• •Increased time to exhaustion
• •Better exercise economy
• •Potentially enhanced high-intensity exercise

Dosing Protocol:

Important considerations:

• •Don't use antibacterial mouthwash: Kills bacteria needed for nitrate conversion
• •Response is individual: Some are non-responders
• •Elite athletes: May respond less than recreational athletes
• •Harmless side effects: Pink/red urine and stool

Contraindications:

• •Caution with blood pressure medications
• •May interact with PDE5 inhibitors (e.g., Viagra)

Evidence rating: ★★★★☆ (Good evidence; individual response varies)

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Vitamin D

What it is: A fat-soluble vitamin (actually a hormone) produced by sun exposure.

Mechanism:

• •Essential for calcium absorption and bone health
• •Affects muscle function
• •Influences immune function
• •May affect testosterone levels

When supplementation is warranted:

• •Blood levels <30 ng/mL (deficiency common in indoor athletes, northern latitudes, dark skin)
• •Limited sun exposure
• •Persistent fatigue or frequent illness

Dosing:

• •Test levels first if possible
• •If deficient: 2,000-5,000 IU daily until replete
• •Maintenance: 1,000-2,000 IU daily (depends on sun exposure)
• •Upper safe limit: 4,000 IU/day (10,000 IU with medical supervision)

Note: Supplementing when not deficient provides no additional benefit for performance.

Evidence rating: ★★★★☆ (Strong for correcting deficiency; less clear for performance in non-deficient athletes)

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Omega-3 Fatty Acids (EPA/DHA)

What it is: Essential fatty acids from fish oil or algae.

Mechanism:

• •Anti-inflammatory effects
• •Incorporated into cell membranes
• •May influence muscle protein synthesis
• •Affects brain function

Benefits:

• •Reduced inflammation and muscle soreness
• •Potential improvements in recovery
• •Cardiovascular and brain health benefits
• •May help with muscle protein synthesis in older athletes

Dosing:

• •1-2g combined EPA+DHA daily
• •Higher doses (3-4g) for more pronounced anti-inflammatory effect
• •With meals (fat-soluble; improves absorption)

Quality matters: Choose products with third-party testing for purity (heavy metals, oxidation).

Evidence rating: ★★★★☆ (Good for general health; performance benefits more modest)

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Tier 3: Moderate Evidence (★★★☆☆)

Sodium Bicarbonate

What it is: Baking soda—an extracellular buffer.

Mechanism:

• •Buffers blood pH during high-intensity exercise
• •Delays acidosis-related fatigue

Benefits:

• •Improved performance in efforts lasting 1-10 minutes
• •May benefit repeated sprint ability

Dosing:

• •0.2-0.3g/kg bodyweight
• •60-90 minutes pre-exercise
• •Can be serial loaded (0.1g/kg 4x leading up to event)

Major drawback: GI distress is common (nausea, diarrhea, cramping). Must trial in training.

Strategies to reduce GI issues:

• •Take with carbohydrate-rich meal
• •Serial loading protocol
• •Individual tolerance varies widely

Evidence rating: ★★★☆☆ (Works but GI issues limit practical application)

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Citrulline

What it is: An amino acid that increases arginine and nitric oxide levels.

Mechanism:

• •Converted to arginine more efficiently than arginine supplements
• •Increases nitric oxide production
• •May reduce fatigue and improve blood flow

Dosing:

• •L-Citrulline: 6-8g, 60 min pre-exercise
• •Citrulline malate: 8-10g (contains malic acid)

Evidence: Promising but less consistent than beetroot/nitrates.

Evidence rating: ★★★☆☆ (Emerging; needs more research)

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What Doesn't Work (★★☆☆☆ or lower)

BCAAs (Branched-Chain Amino Acids)

• •Claim: Preserve muscle, enhance recovery
• •Reality: Unnecessary if protein intake is adequate; may actually impair MPS compared to complete protein
• •Verdict: Save your money; eat protein

Glutamine

• •Claim: Improves immunity and recovery
• •Reality: Supplementation doesn't increase muscle glutamine; no performance benefit in well-fed athletes
• •Verdict: Not recommended

Testosterone Boosters (Tribulus, D-Aspartic Acid, etc.)

• •Claim: Naturally increase testosterone
• •Reality: No consistent evidence of meaningful testosterone increase or performance benefit
• •Verdict: Don't waste money

Fat Burners (Most)

• •Claim: Accelerate fat loss
• •Reality: Most are ineffective or have minimal effect; some are dangerous
• •Exception: Caffeine has modest thermogenic effect
• •Verdict: Diet > pills

Antioxidant Megadoses (Vitamins C, E)

• •Claim: Reduce oxidative stress and improve recovery
• •Reality: May actually blunt training adaptations by interfering with signaling
• •Verdict: Get antioxidants from food; avoid megadosing

Practical Takeaways

• •Most supplements don't work: The supplement industry is largely marketing
• •Only a few have strong evidence: Creatine, caffeine, protein (as convenience)
• •Diet comes first: No supplement compensates for poor nutrition
• •Quality matters: Choose third-party tested products (NSF Certified for Sport, Informed Sport)
• •Individual response varies: What works for one person may not work for another
• •Timing matters less than you think: Consistency is more important than precise timing
• •Don't stack everything: Start with one, assess response, then consider adding

Supplement Decision Framework

1. 1.Is your diet solid? If not, fix that first
2. 2.Does the supplement have strong evidence? If not, probably skip it
3. 3.Does it apply to your sport? Creatine for endurance = minimal benefit
4. 4.Can you afford quality? Cheap supplements may be contaminated
5. 5.Are you willing to test it? Never try new supplements in competition

Common Mistakes

Evidence Quality: ★★★★☆ (varies by supplement)

Supplements with strong evidence: Creatine, caffeine, protein Supplements with moderate evidence: Beta-alanine, nitrates, vitamin D (if deficient) Supplements with weak evidence: Most everything else

Key References

• •Maughan RJ, et al. (2018). IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine. 52(7):439-455.
• •Kreider RB, et al. (2017). International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. Journal of the International Society of Sports Nutrition. 14:18.
• •Guest NS, et al. (2021). International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition. 18:1.
• •Trexler ET, et al. (2015). International society of sports nutrition position stand: Beta-Alanine. Journal of the International Society of Sports Nutrition. 12:30.
• •Jones AM. (2014). Dietary nitrate supplementation and exercise performance. Sports Medicine. 44(Suppl 1):35-45.

Executive Summary

The gut microbiome—trillions of bacteria, fungi, and other microorganisms living in your digestive tract—influences nutrient absorption, immune function, inflammation, and potentially even mental state through the gut-brain axis. While research is still emerging, maintaining a diverse, healthy microbiome through diet appears beneficial for athletes. However, the field is full of hype, and practical applications remain limited.

Deep Dive

What Is the Gut Microbiome?

Composition:

• •~38 trillion bacteria (roughly equal to human cells)
• •1,000+ different species
• •Primarily in the large intestine
• •2-6 pounds of total microbial mass

Key bacterial groups:

• •Firmicutes: Includes beneficial and potentially harmful species
• •Bacteroidetes: Generally beneficial
• •Actinobacteria: Includes bifidobacteria (beneficial)
• •Proteobacteria: Includes some pathogens; ideally low abundance

A "healthy" microbiome:

• •High diversity (many different species)
• •Abundance of beneficial bacteria (Bifidobacteria, Lactobacilli)
• •Low abundance of pathogenic bacteria
• •Appropriate for the individual (no universal "optimal" profile)

Functions of the Gut Microbiome

1. Nutrient Metabolism

Short-Chain Fatty Acid (SCFA) Production:

• •Gut bacteria ferment dietary fiber
• •Produce SCFAs: acetate, propionate, butyrate
• •Butyrate fuels colon cells
• •SCFAs influence metabolism, inflammation, and satiety

Vitamin Synthesis:

• •Some B vitamins (B12, biotin, folate)
• •Vitamin K
• •Amount varies; can't fully meet needs

Calorie Extraction:

• •Microbiome affects how many calories extracted from food
• •May explain some individual variation in weight gain susceptibility
• •"Obese" microbiome patterns may extract more energy

2. Immune Function

70-80% of immune cells reside in the gut.

Microbiome influences:

• •Immune system development and training
• •Inflammation regulation
• •Pathogen resistance
• •Barrier function (gut permeability)

Dysbiosis (imbalanced microbiome) is associated with:

• •Increased inflammation
• •Autoimmune conditions
• •Allergies
• •Frequent infections

3. The Gut-Brain Axis

The gut and brain communicate bidirectionally:

Pathways:

• •Vagus nerve (direct neural connection)
• •Hormonal signals (serotonin, GABA produced in gut)
• •Immune system signaling
• •Microbial metabolites

Implications:

• •Gut health may affect mood and cognition
• •Stress affects gut function
• •"Gut feelings" have biological basis
• •Probiotics show promise for anxiety (limited evidence)

Exercise and the Microbiome

How Exercise Affects the Gut

Positive effects:

• •Increased microbial diversity
• •Higher SCFA-producing bacteria
• •Improved gut barrier function
• •Enhanced beneficial bacteria

Negative effects (excessive/extreme exercise):

• •Temporary gut permeability ("leaky gut")
• •GI symptoms (runner's diarrhea)
• •Blood flow diversion from gut
• •Heat stress effects

The Athlete Microbiome

Research shows elite athletes have:

• •Greater microbial diversity
• •More bacteria associated with amino acid metabolism
• •Higher SCFA production
• •Species potentially linked to lactate metabolism

Causation unclear: Do athletes have better microbiomes because of training, diet, or do better microbiomes help performance?

Nutrition and the Microbiome

Dietary Factors That Shape the Microbiome

Fiber: The Key Driver

Fiber feeds beneficial bacteria, producing SCFAs.

Target: 25-38g daily (most adults get ~15g)

Fiber types:

• •Insoluble fiber (wheat bran, vegetables): Adds bulk
• •Soluble fiber (oats, beans, fruits): Fermentable; feeds bacteria
• •Resistant starch (cooled potatoes, green bananas): Reaches colon; highly fermentable

Prebiotic foods (specifically feed beneficial bacteria):

• •Onions, garlic, leeks
• •Asparagus, Jerusalem artichokes
• •Bananas (especially unripe)
• •Oats, barley
• •Legumes

Fermented Foods

Contain live beneficial bacteria:

• •Yogurt (with live cultures)
• •Kefir
• •Sauerkraut (unpasteurized)
• •Kimchi
• •Kombucha
• •Miso
• •Tempeh

Evidence: Regular consumption associated with improved gut health markers, but most bacteria don't colonize permanently—they pass through.

Practical benefit: May help diversity; certainly not harmful for most people.

Probiotics: What the Evidence Actually Shows

Definition: Live microorganisms that, when consumed in adequate amounts, confer a health benefit.

Evidence Summary for Athletes

What We Know Works (Somewhat)

• •URI reduction: Certain strains (L. rhamnosus, L. casei) may reduce duration of colds
• •GI symptoms: May help with exercise-induced GI distress in some individuals
• •Antibiotic recovery: Helps restore microbiome after antibiotic use

What We Don't Know

• •Which strains for which benefits
• •Optimal dosing
• •Whether effects last after stopping
• •Individual variation in response

Practical Recommendations

If trying probiotics:

• •Look for specific strains with research behind them
• •Choose products with guaranteed CFU at expiration (not just at manufacture)
• •Try for 4+ weeks before judging effectiveness
• •Don't expect miracles

Better approach for most: Focus on fiber and fermented foods rather than supplements.

Prebiotics

Definition: Non-digestible food components that selectively feed beneficial bacteria.

Common prebiotics:

• •Inulin (chicory root)
• •FOS (fructo-oligosaccharides)
• •GOS (galacto-oligosaccharides)
• •Resistant starch

Food sources:

• •Garlic, onions, leeks
• •Asparagus
• •Bananas
• •Oats
• •Legumes
• •Chicory root

Evidence: Prebiotics consistently increase beneficial bacteria and SCFA production.

Caution: Can cause gas and bloating if introduced too quickly. Start slowly.

GI Issues in Athletes

Common problems:

• •Runner's diarrhea
• •Cramping, bloating
• •Nausea during exercise
• •Reflux

Causes:

• •Blood flow diversion from gut during exercise
• •Mechanical jostling (especially running)
• •Dehydration
• •Dietary choices (fiber, fat, certain foods)
• •Stress and nerves

Strategies for GI Management

Before exercise:

• •Low-fiber, low-fat meal
• •Adequate time for digestion (2-4 hours for full meal)
• •Avoid known trigger foods
• •Limit caffeine if sensitive

During exercise:

• •Train your gut (practice race nutrition)
• •Start fueling early (before gut shuts down)
• •Use tolerated products
• •Avoid high-fructose products if sensitive

Chronic issues:

• •Keep food diary to identify triggers
• •Consider FODMAP restriction (with dietitian guidance)
• •Rule out underlying conditions (celiac, IBD)

Leaky Gut: Separating Fact from Fiction

The concept: Increased intestinal permeability allows substances to cross from gut into bloodstream.

Real phenomenon:

• •Exercise temporarily increases permeability
• •Heat stress worsens it
• •Chronic stress can affect gut barrier
• •Some conditions (IBD, celiac) have genuine permeability issues

Overhyped claims:

• •"Leaky gut syndrome" as cause of numerous health issues is not well-supported
• •Many "leaky gut" tests are not validated
• •Many "treatments" are not evidence-based

What helps gut barrier:

• •Adequate sleep
• •Stress management
• •Fiber and polyphenol-rich foods
• •Avoiding excessive alcohol
• •Glutamine (some evidence, modest)

The Future: Microbiome Personalization

Emerging areas:

• •Microbiome testing and personalized recommendations
• •Engineered probiotics
• •Fecal microbiota transplant (for specific conditions)
• •Postbiotics (microbial metabolites as supplements)

Current reality: We can't yet reliably prescribe specific interventions based on microbiome testing. The science isn't there yet.

Practical Takeaways

• •Eat fiber: 25-38g daily; variety of sources
• •Eat plants: Diversity of plant foods = diversity of gut bacteria
• •Include fermented foods: Yogurt, kefir, sauerkraut (not a cure-all, but beneficial)
• •Don't over-rely on probiotics: Food-first approach is more reliable
• •Train your gut: Practice race nutrition
• •Manage stress: Gut-brain axis is real
• •Don't fall for hype: Many microbiome claims are premature

Common Mistakes

Evidence Quality: ★★★☆☆

Well-established:

• •Fiber increases beneficial bacteria and SCFA production
• •Exercise affects microbiome composition
• •Gut-brain communication exists
• •Dysbiosis associated with various conditions

Emerging/uncertain:

• •Specific probiotic recommendations for athletes
• •Causality (does microbiome drive health or reflect it?)
• •Personalized microbiome interventions
• •Performance benefits of microbiome optimization

Key References

• •Mailing LJ, et al. (2019). Exercise and the Gut Microbiome: A Review of the Evidence, Potential Mechanisms, and Implications for Human Health. Exercise and Sport Sciences Reviews. 47(2):75-85.
• •Jäger R, et al. (2019). International Society of Sports Nutrition Position Stand: Probiotics. Journal of the International Society of Sports Nutrition. 16:62.
• •Mohr AE, et al. (2020). The athletic gut microbiota. Journal of the International Society of Sports Nutrition. 17:24.
• •Sonnenburg ED, Sonnenburg JL. (2014). Starving our microbial self: the deleterious consequences of a diet deficient in microbiota-accessible carbohydrates. Cell Metabolism. 20(5):779-786.

Executive Summary

Proper hydration is critical for athletic performance—2-3% dehydration impairs both physical and cognitive function. However, overhydration (hyponatremia) can be equally dangerous, particularly in endurance events. The optimal approach is individualized hydration based on sweat rate, conditions, and exercise duration, guided by thirst rather than rigid drinking schedules.

Deep Dive

Water's Role in the Body

Water comprises 50-70% of body mass and is essential for:

Thermoregulation:

• •Sweat production for evaporative cooling
• •Blood volume maintenance for heat transfer to skin
• •Core temperature regulation during exercise

Nutrient Transport:

• •Delivery of glucose, oxygen, and nutrients to muscles
• •Removal of metabolic waste products
• •Maintenance of blood pressure and cardiac output

Cellular Function:

• •Medium for biochemical reactions
• •Maintenance of cell structure
• •Joint lubrication and cushioning

Sweat Physiology

Sweat Composition

Key insight: Sodium is the primary electrolyte lost in sweat. Potassium and magnesium losses are relatively minor.

Sweat Rate Variation

Sweat rates vary enormously between individuals and conditions:

Individual variation is massive. A 70kg runner might sweat 0.5L/hour in cool conditions and 1.8L/hour in hot, humid conditions.

Dehydration Effects on Performance

Physical Performance Impairment

Mechanisms:

• •Reduced blood volume → decreased cardiac output
• •Increased cardiovascular strain (higher heart rate for same effort)
• •Impaired thermoregulation (less blood to skin for cooling)
• •Altered muscle metabolism

Cognitive Impairment

Dehydration affects cognition at lower levels than physical performance:

• •1-2% dehydration: Impaired attention, mood, and reaction time
• •Particularly relevant for skill-based and team sports
• •Decision-making and concentration affected

The Thirst Mechanism

Thirst is regulated by:

Osmoreceptors: Detect blood concentration Baroreceptors: Detect blood volume/pressure Hormonal signals: AVP (vasopressin), angiotensin II

Is thirst reliable?

Traditional sports science said "drink ahead of thirst" because thirst lags behind dehydration. Current evidence suggests:

• •Thirst is a reliable guide for most exercise situations
• •Drinking to thirst prevents both dehydration AND overhydration
• •Forced drinking schedules can lead to hyponatremia
• •In extreme conditions (very hot, very long), planned hydration may be helpful

Current consensus: Drink to thirst for most situations; develop a hydration plan for extreme conditions or known heavy sweaters.

Hyponatremia: The Other Extreme

Exercise-associated hyponatremia (EAH) occurs when blood sodium drops below 135 mmol/L, typically due to excessive fluid intake.

Risk Factors

• •Slow finishers in endurance events (>4 hours)
• •Drinking beyond thirst
• •Weight gain during exercise
• •Hot conditions with excessive water intake
• •Low body weight
• •Female sex (possibly)

Symptoms by Severity

Key prevention: Don't drink more than you sweat. Weight should not increase during exercise.

Electrolyte Replacement

When Are Electrolytes Needed?

Sodium Guidelines

• •General recommendation: 500-1000 mg/hour for long efforts
• •Heavy/salty sweaters: May need 750-1500 mg/hour
• •Signs you need more: Muscle cramps, white residue on clothes, craving salty food

What About Potassium, Magnesium?

Despite marketing claims:

• •Sweat losses of potassium and magnesium are relatively low
• •Normal diet easily replaces these
• •Sodium is the priority for exercise hydration
• •Post-exercise meals typically provide adequate potassium/magnesium

Calculating Sweat Rate

Method:

1. 1.Weigh yourself nude before exercise
2. 2.Exercise for 1 hour at typical intensity
3. 3.Weigh yourself nude after (towel dry first)
4. 4.Weight loss (kg) = Sweat rate (L/hour)
5. 5.Add any fluid consumed during

Example:

• •Pre-weight: 70.0 kg
• •Post-weight: 68.5 kg
• •Fluid consumed: 500ml
• •Sweat rate = 1.5 + 0.5 = 2.0 L/hour

Adjustment factors:

• •Repeat in different conditions (hot, cold, humid)
• •Note that sweat rate increases with heat acclimatization
• •Higher intensity = higher sweat rate

Practical Hydration Strategies

Pre-Exercise Hydration

Goal: Start exercise euhydrated (normally hydrated)

Don't overhydrate: Starting exercise with a sloshing stomach impairs performance.

During Exercise

General principle: Match intake to losses (or slightly under)

Signs of getting it right:

• •No significant weight gain
• •No significant weight loss (>2-3%)
• •No GI distress
• •Pale to light yellow urine post-exercise

Post-Exercise Rehydration

Goal: Replace 150% of sweat losses over 2-4 hours

Why 150%? Continued urination and obligatory losses mean not all fluid is retained.

Strategy:

• •Calculate weight lost during exercise
• •Consume 1.5L per kg lost
• •Include sodium (aids retention)
• •Spread over several hours
• •Include salty foods with meals

Special Considerations

Heat Acclimatization

Adaptations after 10-14 days of heat exposure:

• •Increased sweat rate (start sweating earlier, sweat more)
• •More dilute sweat (conserve sodium)
• •Expanded plasma volume
• •Lower core temperature at same effort

Implication: Acclimatized athletes may sweat more but need less sodium per liter of sweat.

Cold Weather

• •Thirst sensation reduced in cold
• •Sweat losses still occur (heavy clothing, effort)
• •Urine production increases (cold diuresis)
• •Respiratory water loss increases

Don't forget to hydrate in cold conditions.

Altitude

• •Increased respiratory water loss
• •Increased urination
• •Reduced thirst sensation
• •Higher fluid needs overall

Hydration Assessment Methods

Practical recommendation: Use urine color and body weight together for best assessment.

Practical Takeaways

• •Thirst is usually reliable: Drink to thirst for most exercise situations
• •2-3% dehydration impairs performance: But overdrinking is also harmful
• •Sodium is the key electrolyte: For exercise >60-90 minutes or in heat
• •Individualize: Calculate your sweat rate in various conditions
• •Post-exercise: Replace 150% of losses with electrolyte-containing fluids
• •Weight stability: Neither gain nor lose significant weight during exercise
• •Urine color: Pale yellow indicates adequate hydration

Common Mistakes

Evidence Quality: ★★★★☆

Well-established:

• •Dehydration impairs performance at 2%+
• •Hyponatremia is dangerous and caused by overdrinking
• •Sodium is the primary electrolyte of concern
• •Individual sweat rates vary widely

Ongoing debate:

• •Exact threshold for performance impairment
• •Whether thirst alone is sufficient in all conditions
• •Optimal sodium replacement rates

Key References

• •Sawka MN, et al. (2007). ACSM Position Stand: Exercise and Fluid Replacement. Medicine & Science in Sports & Exercise. 39(2):377-390.
• •Noakes TD. (2012). Waterlogged: The Serious Problem of Overhydration in Endurance Sports. Human Kinetics.
• •Hew-Butler T, et al. (2017). Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference. Clinical Journal of Sport Medicine. 25(4):303-320.
• •Goulet EDB. (2012). Dehydration and endurance performance in competitive athletes. Nutrition Reviews. 70(Suppl 2):S132-S136.

Executive Summary

Nutrition profoundly influences both inflammatory status and immune function. Chronic low-grade inflammation accelerates aging and disease, while acute inflammation is necessary for healing and adaptation. Athletes face unique immune challenges—intense training temporarily suppresses immunity, while proper nutrition can support immune resilience. The goal is to reduce unnecessary chronic inflammation while supporting appropriate acute inflammatory responses.

Deep Dive

Understanding Inflammation

Acute vs. Chronic Inflammation

Acute inflammation (healing a cut, fighting infection):

• •Redness, swelling, heat, pain
• •Immune cells recruited to area
• •Damage repaired, pathogens destroyed
• •Resolves when job is done

Chronic low-grade inflammation ("inflammaging"):

• •Subtle, systemic, persistent
• •Elevated CRP, IL-6, TNF-alpha
• •Drives atherosclerosis, diabetes, cancer, neurodegeneration
• •Often called "silent" inflammation

Exercise and Inflammation: The Paradox

During and immediately after exercise:

• •Inflammatory markers increase (IL-6, CRP)
• •Muscle damage triggers repair signals
• •This is NORMAL and BENEFICIAL

Long-term effect of regular exercise:

• •Reduces chronic inflammation
• •Improves inflammatory resolution
• •Anti-inflammatory effect overall

The concern: Over-training without adequate recovery can shift balance toward chronic inflammation.

Dietary Factors and Inflammation

Pro-Inflammatory Dietary Patterns

Characteristics:

• •High in refined carbohydrates
• •High in processed/ultra-processed foods
• •High in omega-6 relative to omega-3
• •High in saturated and trans fats
• •Low in fiber
• •Low in fruits and vegetables

Specific pro-inflammatory foods:

• •Sugary beverages
• •Refined grains
• •Processed meats
• •Fried foods
• •Trans fats (partially hydrogenated oils)
• •Excessive alcohol

Anti-Inflammatory Dietary Patterns

Characteristics:

• •High in fruits and vegetables (polyphenols, antioxidants)
• •Adequate omega-3 fatty acids
• •High in fiber
• •Moderate in whole grains
• •Includes nuts, seeds, legumes
• •Olive oil as primary fat
• •Moderate or no alcohol

Mediterranean diet is the gold standard anti-inflammatory pattern.

Key Anti-Inflammatory Nutrients

Omega-3 Fatty Acids

Mechanism:

• •Incorporated into cell membranes
• •Compete with omega-6 for inflammatory enzymes
• •Produce anti-inflammatory resolvins and protectins

Sources:

• •Fatty fish (salmon, mackerel, sardines)
• •Algae oil (vegan DHA)
• •Walnuts, flaxseed (ALA—less effective)

Recommendations:

• •2-3 servings fatty fish per week
• •OR 1-2g EPA+DHA supplement daily

The omega-6:omega-3 ratio:

• •Western diet: 15-20:1
• •Optimal: Closer to 4:1 or lower
• •Focus on increasing omega-3, not just reducing omega-6

Evidence rating: ★★★★☆ (Good evidence for reducing inflammation; consistent findings)

Polyphenols

Sources:

• •Berries (anthocyanins)
• •Green tea (EGCG)
• •Dark chocolate (flavanols)
• •Extra virgin olive oil (oleocanthal)
• •Turmeric (curcumin)
• •Red wine (resveratrol)

Mechanisms:

• •Direct antioxidant effects
• •Inhibit inflammatory enzymes
• •Modulate gene expression
• •Support gut microbiome

Practical tip: "Eat the rainbow"—colorful plants contain diverse polyphenols.

Fiber

Anti-inflammatory mechanisms:

• •Feeds beneficial gut bacteria
• •Bacteria produce SCFAs (especially butyrate)
• •SCFAs reduce systemic inflammation
• •Improves gut barrier function

Target: 25-38g daily (most people get ~15g)

The Immune System and Nutrition

How the Immune System Works (Simplified)

Innate immunity (first responders):

• •Physical barriers (skin, mucous membranes)
• •Non-specific cells (neutrophils, macrophages, NK cells)
• •Inflammatory response

Adaptive immunity (specialized response):

• •T cells (cellular immunity)
• •B cells (antibody production)
• •Memory cells (long-term protection)

Nutrients Essential for Immune Function

Key insight: Deficiencies impair immune function, but mega-dosing doesn't enhance it beyond normal.

The Athlete's Immune System

Exercise-Induced Immunosuppression

The "J-curve" hypothesis:

• •Sedentary: Moderate infection risk
• •Moderate exercise: Reduced infection risk
• •Very intense exercise: Increased infection risk (temporarily)

The "open window": After intense exercise, there's a 3-72 hour period of reduced immune function:

• •Decreased natural killer cell activity
• •Reduced mucosal immunity (IgA)
• •Suppressed neutrophil function

When risk is highest:

• •After marathons/ultra-events
• •During heavy training blocks
• •With inadequate recovery
• •Combined with other stressors (travel, sleep deprivation)

Nutritional Strategies for Athlete Immunity

Avoid under-fueling:

• •Low energy availability suppresses immunity
• •Carbohydrates during exercise reduce cortisol and inflammation
• •Post-workout nutrition supports recovery

Specific recommendations:

What Doesn't Work for Immunity

Practical Anti-Inflammatory Protocol

Daily Practices

Foods to emphasize:

• •Fatty fish 2-3x/week
• •Olive oil as primary cooking fat
• •5+ servings vegetables daily
• •2+ servings fruit daily
• •Nuts and seeds daily
• •Legumes several times weekly
• •Green tea or coffee

Foods to minimize:

• •Sugary beverages
• •Ultra-processed foods
• •Excessive red meat
• •Trans fats
• •Refined grains

Around Exercise

During intense/prolonged exercise:

• •Carbohydrates reduce immune suppression
• •30-60g/hour for sessions >60 minutes

Post-exercise:

• •Adequate protein and carbs
• •Don't intentionally under-eat

During Illness

Nutrition priorities:

• •Hydration (especially with fever)
• •Adequate calories (don't force if no appetite)
• •Protein for immune function
• •Zinc (30mg) at first sign of cold

Training adjustment:

• •Above the neck symptoms (runny nose, sneezing): Light exercise OK
• •Below the neck symptoms (cough, body aches, fever): REST
• •Return gradually; don't rush back

Sleep: The Unsung Immune Hero

Sleep deprivation:

• •Reduces antibody response to vaccines
• •Increases inflammatory markers
• •Increases cold susceptibility 4x (with <6 hours sleep)
• •Impairs recovery

Recommendation: 7-9 hours for athletes; may need more during heavy training.

Practical Takeaways

• •Diet pattern matters most: Mediterranean-style eating is anti-inflammatory
• •Omega-3s are important: Fatty fish 2-3x/week or supplement
• •Colorful plants provide polyphenols: Eat the rainbow
• •Don't under-fuel: Low energy availability suppresses immunity
• •Carbs during exercise: Reduce immune suppression in long sessions
• •Sleep is non-negotiable: Critical for immune function
• •Supplements are secondary: No pill replaces good diet and sleep
• •Chronic inflammation is the enemy: Not acute post-exercise inflammation

Common Mistakes

Evidence Quality: ★★★★☆

Well-established:

• •Diet pattern influences inflammatory markers
• •Omega-3s have anti-inflammatory effects
• •Exercise-induced immunosuppression exists
• •Under-fueling suppresses immunity

Emerging/uncertain:

• •Optimal supplement protocols for athletes
• •Specific probiotic strains for immunity
• •Best strategies to minimize "open window"

Key References

• •Calder PC, et al. (2017). Health relevance of the modification of low grade inflammation in ageing (inflammageing) and the role of nutrition. Ageing Research Reviews. 40:95-119.
• •Walsh NP, et al. (2011). Position statement. Part one: Immune function and exercise. Exercise Immunology Review. 17:6-63.
• •Nieman DC, Wentz LM. (2019). The compelling link between physical activity and the body's defense system. Journal of Sport and Health Science. 8(3):201-217.
• •Gleeson M, et al. (2011). Exercise, nutrition and immune function. Journal of Sports Sciences. 22(1):115-125.

Executive Summary

Nutrition significantly influences healthspan and lifespan. Caloric restriction, intermittent fasting, and specific dietary patterns activate longevity-promoting pathways (AMPK, sirtuins, autophagy) while inhibiting aging-accelerating pathways (mTOR overactivation, chronic inflammation). For athletes, the challenge is balancing longevity-promoting practices with performance optimization—these goals sometimes conflict. The evidence supports moderate caloric intake, adequate protein (with caveats), plant-rich diets, and time-restricted eating as promising approaches.

Deep Dive

The Hallmarks of Aging and Nutrition

Aging is driven by interconnected cellular processes. Nutrition influences several:

Key Longevity Pathways

mTOR (mechanistic Target of Rapamycin)

Function: Master growth regulator; promotes protein synthesis and cell growth

Activated by:

• •Amino acids (especially leucine)
• •Insulin/IGF-1
• •Sufficient energy

Longevity implications:

• •Chronic mTOR activation accelerates aging
• •mTOR inhibition (rapamycin) extends lifespan in animals
• •Trade-off: mTOR needed for muscle protein synthesis

Practical balance:

• •Pulse protein intake (activate mTOR periodically, not constantly)
• •Fasting periods allow mTOR downregulation
• •Don't eat constantly; avoid 24/7 elevated mTOR

AMPK (AMP-Activated Protein Kinase)

Function: Cellular energy sensor; activated when energy is low

Activated by:

• •Fasting
• •Exercise
• •Caloric restriction
• •Metformin (diabetes drug)
• •Certain polyphenols (resveratrol)

Benefits:

• •Increases autophagy
• •Improves mitochondrial function
• •Enhances fat oxidation
• •Inhibits mTOR

How to activate:

• •Time-restricted eating
• •Exercise (especially when glycogen-depleted)
• •Occasional fasting periods

Sirtuins

Function: Family of proteins involved in cellular regulation and stress resistance

Activated by:

• •NAD+ availability
• •Caloric restriction
• •Exercise
• •Certain polyphenols

Benefits:

• •DNA repair
• •Mitochondrial function
• •Inflammation reduction
• •Metabolic regulation

NAD+ and aging: NAD+ declines with age. NAD+ precursors (NMN, NR) are being studied but evidence in humans is still limited.

Autophagy

Function: Cellular "cleanup"; degrades and recycles damaged components

Activated by:

• •Fasting (strongest trigger)
• •Exercise
• •Low protein periods
• •Certain compounds (spermidine, coffee)

Benefits:

• •Removes damaged proteins and organelles
• •Reduces cellular waste accumulation
• •May prevent neurodegeneration
• •Cancer prevention (removes damaged cells)

How to promote:

• •Extended fasting (16+ hours)
• •Periodic protein restriction
• •Regular exercise

Caloric Restriction (CR)

Definition: Reducing caloric intake 20-40% below ad libitum while maintaining nutrition.

Evidence

Human evidence:

• •CALERIE trial: 25% CR for 2 years reduced cardiovascular risk factors
• •Okinawan centenarians practiced mild CR historically
• •CR practitioners show improved metabolic markers

Mechanisms

1. 1.Reduced mTOR activation
2. 2.Increased AMPK and autophagy
3. 3.Lower oxidative stress
4. 4.Reduced inflammation
5. 5.Improved insulin sensitivity
6. 6.Enhanced DNA repair

Practical Considerations for Athletes

The problem: Athletes need fuel for performance and recovery. Chronic CR:

• •Impairs training adaptations
• •Reduces recovery
• •Can cause RED-S (Relative Energy Deficiency in Sport)
• •May reduce muscle mass

The balance:

• •Mild caloric restraint on rest days
• •Adequate fuel for training days
• •Time-restricted eating (see below)
• •Focus on nutrient density, not just restriction

Intermittent Fasting (IF)

Types of IF

Benefits Supported by Evidence

Metabolic:

• •Improved insulin sensitivity
• •Reduced fasting glucose
• •Lower triglycerides
• •Weight loss (if caloric deficit achieved)

Cellular:

• •Autophagy activation (requires longer fasts)
• •mTOR downregulation
• •AMPK activation
• •Ketone production

What About IF for Athletes?

Potential benefits:

• •Metabolic flexibility
• •Fat adaptation
• •Simplified eating schedule

Potential drawbacks:

• •Difficulty fitting adequate calories in eating window
• •Performance may suffer if training fasted
• •Recovery may be impaired without post-workout nutrition
• •Risk of under-fueling

Practical approach:

• •Time eating window around training
• •Fuel quality sessions
• •Consider 12-14 hour overnight fast rather than 16+
• •Avoid IF during heavy training phases

Protein: The Longevity Paradox

The dilemma: Protein activates mTOR (pro-aging) but is essential for muscle mass (anti-frailty).

Low Protein and Longevity

Animal studies: Low-protein diets extend lifespan in some models.

Human epidemiology:

• •Lower protein intake associated with reduced cancer mortality in middle age
• •BUT: higher protein associated with reduced mortality in elderly

The pattern: Protein restriction may benefit younger/middle-aged adults but becomes harmful in older adults.

Protein Recommendations Across Lifespan

Key insight: Sarcopenia (muscle loss) is a major driver of frailty and mortality in elderly. Protein restriction in old age is harmful.

Dietary Patterns for Longevity

Mediterranean Diet

Components:

• •High olive oil
• •Abundant vegetables and fruits
• •Moderate fish and poultry
• •Limited red meat
• •Whole grains
• •Legumes
• •Moderate red wine (optional)

Evidence: ★★★★★

• •Reduces cardiovascular mortality by 30%
• •Reduces cognitive decline
• •Associated with longer telomeres
• •PREDIMED trial: strong evidence for heart health

Blue Zones Patterns

Common factors in longest-lived populations:

• •Plant-forward diet (~95% plant-based)
• •Legumes as protein staple
• •Whole grains
• •Moderate calories (natural mild CR)
• •Social eating
• •Limited meat (mostly pork in small amounts)
• •Moderate alcohol (optional)

Plant-Based Diets

Evidence:

• •Associated with lower all-cause mortality
• •Reduced cardiovascular disease
• •Lower cancer risk (some types)
• •Environmental sustainability benefit

Considerations:

• •Must be well-planned (B12, iron, zinc, omega-3)
• •Not necessarily superior to other healthy patterns
• •"Plant-based junk food" not beneficial

Specific Nutrients and Longevity

Polyphenols

Found in colorful plants, tea, coffee, red wine, dark chocolate.

Mechanisms:

• •AMPK activation
• •Sirtuin activation
• •Anti-inflammatory
• •Antioxidant

Best sources:

• •Berries
• •Green tea
• •Coffee
• •Extra virgin olive oil
• •Dark chocolate
• •Red wine (in moderation, if at all)

Omega-3 Fatty Acids

Evidence:

• •Reduced cardiovascular mortality
• •Anti-inflammatory
• •Brain health
• •Telomere preservation (some evidence)

Sources:

• •Fatty fish (salmon, mackerel, sardines)
• •Algae (vegan source)
• •Walnuts, flaxseed (ALA, less effective)

Spermidine

Found in wheat germ, aged cheese, mushrooms, legumes.

Mechanism: Induces autophagy

Evidence: Associated with reduced mortality in epidemiological studies; human trials underway.

What Doesn't Work (or Lacks Evidence)

Practical Takeaways

• •Eat mostly plants: Vegetables, fruits, legumes, whole grains
• •Don't overeat: Mild caloric restraint (without under-fueling for training)
• •Time-restrict eating: 12-16 hour overnight fast; avoid constant eating
• •Pulse protein: Don't graze on protein all day; concentrate in meals
• •Prioritize food quality: Mediterranean-style eating pattern
• •Adequate protein in older age: Sarcopenia is the enemy
• •Include polyphenol-rich foods: Tea, coffee, berries, olive oil
• •Don't rely on supplements: Focus on dietary pattern

Common Mistakes

Evidence Quality: ★★★☆☆

Well-established:

• •Caloric restriction extends lifespan in animals
• •Mediterranean diet reduces cardiovascular mortality
• •Protein is essential for preventing sarcopenia
• •mTOR, AMPK, and autophagy pathways exist and are diet-modifiable

Emerging/uncertain:

• •Optimal human CR without downsides
• •Best IF protocols for longevity
• •Protein "sweet spot" across lifespan
• •Specific supplement benefits (NMN, NR, etc.)

Key References

• •Longo VD, Anderson RM. (2022). Nutrition, longevity and disease: From molecular mechanisms to interventions. Cell. 185(9):1455-1470.
• •de Cabo R, Mattson MP. (2019). Effects of Intermittent Fasting on Health, Aging, and Disease. NEJM. 381(26):2541-2551.
• •Fontana L, Partridge L. (2015). Promoting health and longevity through diet: from model organisms to humans. Cell. 161(1):106-118.
• •Levine ME, et al. (2014). Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metabolism. 19(3):407-417.

Executive Summary

Macronutrients—carbohydrates, fats, and proteins—are metabolized through distinct biochemical pathways to produce ATP, the energy currency of cells. Understanding these pathways helps athletes optimize fuel selection based on exercise intensity and duration. Metabolic flexibility, the ability to switch between fuel sources efficiently, is a hallmark of trained athletes.

Deep Dive

Carbohydrate Metabolism

Glycolysis: The Universal Pathway

Glycolysis converts glucose to pyruvate in the cytoplasm, yielding 2 ATP per glucose molecule. This 10-step pathway operates in both aerobic and anaerobic conditions.

Key Steps:

1. 1.Hexokinase traps glucose in the cell by phosphorylation
2. 2.Phosphofructokinase (PFK) is the rate-limiting enzyme, regulated by ATP, AMP, and citrate
3. 3.Pyruvate kinase produces the final ATP

Regulation:

• •High ATP inhibits PFK (energy sufficient)
• •High AMP activates PFK (energy needed)
• •Insulin promotes glucose uptake via GLUT4 transporters

Aerobic vs Anaerobic Fate

Aerobic (with oxygen):

• •Pyruvate enters mitochondria
• •Converted to acetyl-CoA by pyruvate dehydrogenase
• •Enters citric acid cycle (Krebs cycle)
• •Complete oxidation yields ~32-34 ATP per glucose

Anaerobic (without sufficient oxygen):

• •Pyruvate converted to lactate by lactate dehydrogenase
• •Regenerates NAD+ to continue glycolysis
• •Yields only 2 ATP per glucose
• •Lactate can be reconverted to glucose in liver (Cori cycle)

Glycogen: The Storage Form

Glycogen is the storage form of glucose in muscle and liver.

Muscle glycogen:

• •~400-500g in trained athletes (can be increased with carb loading)
• •Used locally by muscle
• •Cannot be exported to blood (lacks glucose-6-phosphatase)
• •Primary fuel for high-intensity exercise

Liver glycogen:

• •~80-120g capacity
• •Maintains blood glucose levels
• •Can be depleted in 12-18 hours of fasting
• •Released via glycogenolysis

Gluconeogenesis: Making New Glucose

When carbohydrate availability is low, the liver (and to lesser extent, kidneys) can synthesize glucose from non-carbohydrate precursors:

• •Lactate (Cori cycle)
• •Amino acids (especially alanine, via glucose-alanine cycle)
• •Glycerol (from fat breakdown)

This process is energetically expensive (6 ATP per glucose) but essential for maintaining blood glucose during fasting or prolonged exercise.

Fat Metabolism

Lipolysis: Mobilizing Fat Stores

Adipose tissue releases fatty acids through lipolysis:

1. 1.Hormone-sensitive lipase (HSL) breaks down triglycerides
2. 2.Activated by catecholamines, glucagon, cortisol
3. 3.Inhibited by insulin (why high carb intake blunts fat oxidation)
4. 4.Releases free fatty acids (FFA) and glycerol into blood

Beta-Oxidation: Burning Fat for Fuel

Fatty acids are broken down in the mitochondria through beta-oxidation:

1. 1.Fatty acids activated to acyl-CoA in cytoplasm
2. 2.Transported into mitochondria via carnitine shuttle (CPT-I, CPT-II)
3. 3.Sequential removal of 2-carbon units as acetyl-CoA
4. 4.Acetyl-CoA enters citric acid cycle

Energy yield:

• •Palmitate (16-carbon fatty acid): ~106 ATP
• •Much higher energy per gram than carbohydrate
• •But requires more oxygen per ATP produced

Rate Limitations:

• •Carnitine shuttle capacity (CPT-I is rate-limiting)
• •Oxygen availability
• •Slower than carbohydrate oxidation
• •Cannot support very high-intensity exercise

Ketogenesis: Alternative Brain Fuel

When carbohydrates are severely restricted:

1. 1.Excess acetyl-CoA in liver diverted to ketone bodies
2. 2.Acetoacetate, beta-hydroxybutyrate, acetone produced
3. 3.Ketones can cross blood-brain barrier
4. 4.Provide alternative fuel for brain and muscle

Relevance for athletes:

• •Keto-adaptation takes 2-4 weeks
• •May benefit ultra-endurance (spares glycogen)
• •Impairs high-intensity performance (>80% VO2max)
• •Not recommended for most athletes

Protein Metabolism

Protein Synthesis (Anabolism)

Muscle protein synthesis (MPS) is the process of building new muscle proteins:

1. 1.mTORC1 is the master regulator
2. 2.Activated by amino acids (especially leucine), insulin, and mechanical tension
3. 3.Leucine threshold: ~2-3g leucine triggers maximal MPS
4. 4.Refractory period: MPS remains elevated for ~3-5 hours post-stimulus

Key insights:

• •Distribute protein across 4-5 meals
• •~0.4-0.55g/kg per meal optimizes MPS
• •Total daily protein matters more than exact timing

Protein Breakdown (Catabolism)

Muscle protein breakdown (MPB) is regulated by:

1. 1.Ubiquitin-proteasome pathway (main pathway)
2. 2.Autophagy (cellular recycling)
3. 3.Increased by fasting, cortisol, inactivity
4. 4.Decreased by insulin, amino acids, resistance exercise

Net muscle balance = MPS - MPB

For muscle growth, MPS must exceed MPB over time.

Amino Acid Oxidation

Amino acids can be used for energy, especially during prolonged exercise:

1. 1.BCAAs (leucine, isoleucine, valine) oxidized directly in muscle
2. 2.Alanine and glutamine exported to liver
3. 3.Carbon skeletons enter citric acid cycle
4. 4.Nitrogen excreted as urea

During exercise:

• •Amino acid oxidation increases with duration
• •May contribute 5-15% of energy in long events
• •Higher when glycogen depleted

Metabolic Flexibility

Metabolic flexibility refers to the ability to efficiently switch between fuel sources based on availability and demand.

Characteristics of metabolically flexible athletes:

• •High fat oxidation at rest and low intensities
• •Rapid switch to carbohydrate at high intensities
• •Better glycogen sparing during prolonged exercise
• •Can adapt to various nutritional strategies

Improving metabolic flexibility:

• •Regular aerobic exercise
• •Some fasted or low-carb training (periodized)
• •Adequate sleep and stress management
• •Avoiding chronic high-carb intake

Substrate Utilization by Exercise Intensity

Practical Takeaways

• •Match fuel to intensity: High-intensity work requires carbohydrates; low-intensity can rely more on fat
• •Glycogen is limited: ~90-120 minutes of high-intensity work depletes muscle glycogen
• •Fat oxidation has an upper limit: Cannot sustain very high intensities
• •Protein sparing: Adequate carbs and calories reduce muscle protein breakdown
• •Metabolic flexibility is trainable: Periodized nutrition can enhance fuel selection efficiency
• •Fasting adaptations: The body adapts to low-carb states but at the cost of high-intensity capacity

Common Mistakes

Evidence Quality: ★★★★★

Well-established:

• •Glycolysis, beta-oxidation, and protein synthesis pathways are textbook biochemistry
• •Substrate utilization by intensity is well-characterized
• •Glycogen's role in high-intensity performance is clear

Areas of ongoing research:

• •Optimal strategies for metabolic flexibility
• •Individual variation in fuel utilization
• •Ketone supplementation effects

Key References

• •Hargreaves M, Spriet LL. (2020). Skeletal muscle energy metabolism during exercise. Nature Metabolism. 2(9):817-828.
• •Jeukendrup AE. (2017). Periodized nutrition for athletes. Sports Medicine. 47(Suppl 1):51-63.
• •Hawley JA, et al. (2018). Maximizing Cellular Adaptation to Endurance Exercise in Skeletal Muscle. Cell Metabolism. 27(5):962-976.
• •Burke LM, et al. (2017). Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. The Journal of Physiology. 595(9):2785-2807.

Overview

Nutrition has a powerful psychological component. Research shows diet influences cognitive performance, mindful eating improves eating behaviors, and the relationship between athletes and food requires psychological awareness. A healthy mental approach to nutrition supports both performance and wellbeing.

The Psychology of Eating

Mind-Body Nutrition Connection

Research Findings:

• •Diet affects cognitive performance (focus, memory, decision-making)
• •Gut-brain axis links digestive health to mental state
• •Blood sugar fluctuations affect mood and energy
• •Hydration status impacts cognition

Eating Under Stress

Athletes face unique eating challenges:

• •Performance pressure affecting appetite
• •Stress eating or under-eating
• •Body composition concerns
• •Schedule constraints on eating

The Athlete-Food Relationship

Healthy Relationship:

• •Food as fuel and enjoyment
• •Flexibility within structure
• •Body awareness and response
• •Sustainable long-term patterns

Warning Signs:

• •Rigid, rule-based eating
• •Fear of certain foods
• •Eating disconnected from hunger
• •Identity overly tied to diet

Core Mental Skills for Nutrition

1. Mindful Eating

Definition: Paying full attention to the experience of eating—taste, texture, hunger, satisfaction.

Benefits for Athletes:

• •Better hunger/fullness awareness
• •Improved digestion
• •Reduced emotional eating
• •Enhanced eating satisfaction

Mindful Eating Practice:

1. 1.Before Eating:

• •Check hunger level (1-10 scale)
• •Notice emotional state
• •Set intention for the meal

1. 1.During Eating:

• •Slow down
• •Taste food fully
• •Notice texture and temperature
• •Chew thoroughly
• •Put fork down between bites

1. 1.After Eating:

• •Check satisfaction level
• •Notice energy changes
• •Appreciate the nourishment

2. Emotional Eating Awareness

Recognizing Emotional Eating:

• •Eating when not physically hungry
• •Eating to manage emotions (stress, boredom, sadness)
• •Craving specific "comfort" foods
• •Eating past fullness

Strategies:

1. 1.Pause Before Eating:

• •"Am I physically hungry or emotionally hungry?"
• •Rate hunger on 1-10 scale
• •Identify the trigger

1. 1.Address Emotions Directly:

• •What am I really feeling?
• •What do I actually need? (rest, connection, movement)
• •Non-food strategies for the emotion

1. 1.Eat Mindfully Anyway:

• •If you choose to eat, do so consciously
• •No judgment—just awareness
• •Learning opportunity

3. Body Awareness and Hunger

Hunger-Fullness Awareness:

Developing Awareness:

• •Check in before meals
• •Pause mid-meal to assess
• •Notice energy 1-2 hours after eating
• •Track patterns

4. Performance Nutrition Psychology

Eating for Training:

• •Fuel appropriately (not restrict)
• •Timing matters for performance
• •Post-workout nutrition is recovery
• •Consistency over perfection

Pre-Competition Eating:

• •Familiar foods only (no experiments)
• •Adequate but not heavy
• •Calm, unhurried eating
• •Trust your plan

Competition Day Psychology:

• •Stick to routine
• •Don't let anxiety affect eating
• •Eat despite nervousness
• •Trust preparation

5. Flexibility and Balance

The 80/20 Approach:

• •80% nutrient-dense, performance-supporting foods
• •20% flexibility for enjoyment, social eating, preferences
• •No food is "bad"—context matters

Why Flexibility Matters:

• •Rigid diets are unsustainable
• •Restriction often leads to bingeing
• •Food should be enjoyed
• •Social eating is part of life

Practicing Flexibility:

• •Include favorite foods regularly
• •Don't compensate with extra exercise
• •Eat socially without anxiety
• •Trust your body's regulation

6. Self-Talk Around Food

Unhelpful Self-Talk:

• •"I was bad for eating that"
• •"I need to burn this off"
• •"I can't eat carbs"
• •"I have no self-control"

Helpful Reframes:

• •"I ate what I needed"
• •"My body uses all fuel"
• •"Carbs support my training"
• •"I can trust my hunger"

Disordered Eating Awareness

Risk Factors in Athletes

Sports with Higher Risk:

• •Weight-class sports (wrestling, boxing, rowing)
• •Aesthetic sports (gymnastics, figure skating)
• •Endurance sports (running, cycling)
• •Sports emphasizing leanness

Warning Signs:

• •Preoccupation with food and body
• •Rigid food rules
• •Excessive exercise to "earn" food
• •Avoiding social eating
• •Hiding eating behaviors
• •Rapid weight changes

When to Seek Help

If you notice:

• •Eating behaviors affecting performance
• •Anxiety around food
• •Inability to eat flexibly
• •Body image distress
• •Any purging or severe restriction

Professional support from a sports dietitian and/or therapist is recommended.

Nutrition Timing Psychology

Consistency vs. Perfection

Consistency Wins:

• •Regular eating patterns
• •Adequate energy availability
• •Sustainable habits
• •Long-term perspective

Perfection Backfires:

• •Rigid rules create stress
• •All-or-nothing leads to cycles
• •Missing one meal isn't failure
• •Flexibility is health

Habit Building

Small, Sustainable Changes:

• •One change at a time
• •Build on success
• •Allow adjustment period
• •Progress over perfection

Environment Design:

• •Make good choices easy
• •Prep meals in advance
• •Stock healthy options
• •Remove decision fatigue

Body Composition Psychology

Healthy vs. Unhealthy Pursuit

Healthy Approach:

• •Gradual, sustainable changes
• •Adequate fueling maintained
• •Performance as primary metric
• •Body acceptance alongside goals

Unhealthy Approach:

• •Rapid, extreme changes
• •Underfueling for training
• •Appearance as sole focus
• •Self-worth tied to body

The Performance-Appearance Balance

Key Insight: Optimal performance body ≠ leanest possible body

• •Underfueling impairs performance
• •Recovery requires adequate energy
• •Hormonal health requires body fat
• •Long-term thinking matters

Mental Recovery Through Nutrition

Food for Mental State

• •Blood sugar stability → mood stability
• •Omega-3s → brain health
• •Gut health → mental wellbeing
• •Adequate calories → cognitive function

Post-Training Recovery Eating

Mental Component:

• •Recovery nutrition as self-care
• •Deliberate refueling
• •Appreciation for what body did
• •Setting up next session

References

1. 1.Mathieu, J. (2009). What should you know about mindful and intuitive eating? Journal of the American Dietetic Association.
2. 2.Bratland-Sanda, S., & Sundgot-Borgen, J. (2013). Eating disorders in athletes: Overview of prevalence, risk factors and recommendations for prevention and treatment. European Journal of Sport Science.
3. 3.Mountjoy, M., et al. (2018). International Olympic Committee consensus statement on relative energy deficiency in sport. British Journal of Sports Medicine.
4. 4.Tylka, T.L. (2006). Development and psychometric evaluation of a measure of intuitive eating. Journal of Counseling Psychology.

Executive Summary

Micronutrients—vitamins and minerals—are essential for energy metabolism, immune function, bone health, and recovery. Athletes have increased needs for certain micronutrients due to higher metabolic demands and losses through sweat. While supplementation is rarely necessary with a balanced diet, specific populations (vegans, athletes with restricted diets, those in caloric deficit) may benefit from targeted supplementation.

Deep Dive

Athlete-Specific Micronutrient Concerns

Athletes face unique challenges:

• •Increased metabolic turnover
• •Sweat losses (sodium, potassium, zinc, iron)
• •Higher oxidative stress
• •Potential for restricted eating
• •Caloric deficits during weight management

Key Micronutrients for Athletes

Iron

Function:

• •Oxygen transport (hemoglobin in blood, myoglobin in muscle)
• •Electron transport chain (energy production)
• •Immune function

Why athletes are at risk:

• •Foot-strike hemolysis (running)
• •Sweat losses
• •GI bleeding from intense exercise
• •Menstruation (females)
• •Low-energy diets

Stages of Iron Deficiency:

Recommendations:

• •Get tested annually (ferritin + hemoglobin)
• •Food sources: Red meat, poultry, fish, fortified cereals, legumes
• •Enhance absorption: Vitamin C with iron-rich foods; avoid tea/coffee with meals
• •Supplementation: Only if deficient (50-100mg elemental iron daily with vitamin C)

Evidence rating: ★★★★★ (Well-established importance; supplementation when deficient clearly beneficial)

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Vitamin D

Function:

• •Calcium absorption and bone health
• •Muscle function
• •Immune modulation
• •May affect testosterone levels

Why athletes are at risk:

• •Indoor training
• •Northern latitudes
• •Darker skin pigmentation
• •Sunscreen use
• •Winter months

Optimal Levels:

Recommendations:

• •Test levels, especially in winter
• •If deficient: 2,000-5,000 IU daily until replete
• •Maintenance: 1,000-2,000 IU daily (if limited sun)
• •Take with fat-containing meal (fat-soluble)

Evidence rating: ★★★★☆ (Clear for deficiency correction; less clear for optimizing already-sufficient levels)

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Calcium

Function:

• •Bone mineralization
• •Muscle contraction
• •Nerve transmission
• •Blood clotting

Athlete considerations:

• •High bone turnover from impact sports
• •Sweat losses
• •Low energy availability reduces bone formation
• •Female Athlete Triad/RED-S includes bone loss

Requirements:

• •Adults: 1,000 mg/day
• •Adolescents/young adults: 1,300 mg/day
• •May need more during caloric deficit

Food sources:

• •Dairy (300mg per cup milk)
• •Fortified plant milks
• •Leafy greens (kale, bok choy)
• •Fortified foods
• •Canned fish with bones

Supplementation:

• •Only if dietary intake inadequate
• •Split doses (500mg max per dose for absorption)
• •Calcium carbonate: take with food
• •Calcium citrate: can take any time

Evidence rating: ★★★★☆ (Essential nutrient; supplementation only when dietary intake insufficient)

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B Vitamins

Functions:

• •Energy metabolism (B1, B2, B3, B5, B6)
• •Red blood cell formation (B12, folate)
• •Nervous system function (B12, B6)

At-risk populations:

• •Vegans (B12)
• •Athletes in caloric deficit
• •Those with GI issues

Key B Vitamins for Athletes:

B12 for vegans:

• •MUST supplement (2.4 mcg daily or 1000 mcg 2-3x/week)
• •No reliable plant sources
• •Deficiency can cause irreversible nerve damage

Evidence rating: ★★★★☆ (Essential; B12 supplementation critical for vegans)

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Magnesium

Function:

• •300+ enzymatic reactions
• •Muscle and nerve function
• •Energy production
• •Protein synthesis

Athlete considerations:

• •Sweat losses
• •Potential for inadequate intake
• •May affect sleep and recovery

Deficiency signs:

• •Muscle cramps
• •Fatigue
• •Poor sleep
• •Irregular heartbeat (severe)

Recommendations:

• •Men: 400-420 mg/day
• •Women: 310-320 mg/day
• •Food sources: Nuts, seeds, legumes, whole grains, leafy greens
• •Supplementation: Magnesium glycinate or citrate if needed (200-400mg)

Note: Many athletes supplement magnesium for sleep. Evidence is mixed but generally safe.

Evidence rating: ★★★☆☆ (Important nutrient; supplementation benefit unclear in non-deficient individuals)

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Zinc

Function:

• •Immune function
• •Protein synthesis
• •Wound healing
• •Testosterone production

Athlete considerations:

• •Sweat losses
• •Vegetarians/vegans (lower absorption from plant sources)
• •May be low in caloric deficit

Requirements:

• •Men: 11 mg/day
• •Women: 8 mg/day
• •Upper limit: 40 mg/day

Food sources:

• •Oysters, beef, crab
• •Poultry, pork
• •Legumes, nuts, seeds
• •Fortified cereals

Supplementation: Generally not needed with adequate diet; may impair copper absorption if excessive.

Evidence rating: ★★★☆☆ (Important for immunity; unnecessary for most athletes eating varied diet)

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Antioxidants: A Cautionary Tale

The hypothesis: Exercise increases oxidative stress → antioxidants should help.

The reality: Exercise-induced oxidative stress is a SIGNAL for adaptation. Blocking it with supplements may actually IMPAIR training adaptations.

Evidence Against Mega-Dosing

Recommendation: Get antioxidants from FOOD (fruits, vegetables), not supplements. The food matrix provides balanced, moderate amounts.

Evidence rating: ★★★★☆ (Strong evidence that mega-dosing is counterproductive)

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Micronutrient Interactions

Nutrients don't act in isolation:

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Testing: What's Worth Measuring?

Recommended for athletes:

• •Ferritin (iron stores) - annually or if fatigued
• •Hemoglobin (anemia screening) - with ferritin
• •Vitamin D (25-OH-D) - annually, especially winter

Consider if symptomatic:

• •B12 (especially vegans)
• •Full iron panel if anemia suspected

Usually not worth testing:

• •Magnesium (blood levels don't reflect body stores)
• •Zinc (unless specific concerns)
• •General "micronutrient panels" (expensive, often not actionable)

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Population-Specific Recommendations

Vegans

Must supplement:

• •B12 (no negotiation)
• •Consider: Vitamin D, iron, zinc, omega-3 (algae-based)

Female Athletes

Pay attention to:

• •Iron (menstrual losses)
• •Calcium (bone health)
• •Vitamin D

Athletes in Caloric Deficit

Increased needs:

• •All micronutrients (less food = less nutrients)
• •Consider multivitamin
• •Iron and calcium especially

Masters Athletes (40+)

Consider:

• •Vitamin D (skin produces less)
• •B12 (absorption declines)
• •Calcium (bone maintenance)

Practical Takeaways

• •Food first: A varied diet provides most micronutrients
• •Test, don't guess: Iron and vitamin D worth testing
• •Vegans MUST supplement B12: No exceptions
• •Don't mega-dose antioxidants: May impair adaptations
• •Iron + vitamin C: Enhance absorption when needed
• •Caloric deficit increases risk: Consider multivitamin during cutting
• •Quality over quantity: Bioavailability matters more than total amount

Common Mistakes

Evidence Quality: ★★★★☆

Well-established:

• •Iron deficiency impairs performance; supplementation helps when deficient
• •B12 essential for vegans
• •Vitamin D deficiency common and worth correcting
• •Antioxidant mega-dosing may impair adaptation

Less certain:

• •Optimal levels beyond preventing deficiency
• •Benefits of micronutrient supplementation in well-nourished athletes

Key References

• •Thomas DT, et al. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and ACSM: Nutrition and Athletic Performance. JAND. 116(3):501-528.
• •Peeling P, et al. (2018). Athletic induced iron deficiency: new insights into the role of inflammation, cytokines and hormones. European Journal of Applied Physiology. 118(1):1-15.
• •Owens DJ, et al. (2015). Vitamin D and the athlete: current perspectives and new challenges. Sports Medicine. 45(Suppl 1):S107-S112.
• •Ristow M, et al. (2009). Antioxidants prevent health-promoting effects of physical exercise in humans. PNAS. 106(21):8665-8670.

Executive Summary

Nutrition is rife with myths, misconceptions, and legitimate controversies. This guide separates evidence from hype, addressing common beliefs that don't hold up to scrutiny and controversies where the science is genuinely unsettled. Understanding where myths originated helps recognize why they persist and how to evaluate new claims critically.

Deep Dive

Debunked Myths

1. "Eating Fat Makes You Fat"

Origin: 1980s low-fat diet craze; oversimplified interpretation of calories.

The myth: Dietary fat is uniquely fattening and should be minimized.

The truth:

• •All macronutrients can be stored as fat in caloric surplus
• •Fat is more calorie-dense (9 kcal/g vs 4 kcal/g) but also more satiating
• •Low-fat diets often replaced fat with refined carbs (worse outcome)
• •Mediterranean diet (high in olive oil) is protective

Current understanding: Fat quality matters more than quantity. Unsaturated fats are beneficial. Total calories determine weight.

Evidence rating: ★★★★★ (Myth thoroughly debunked)

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2. "Carbs Are Bad / Carbs Make You Fat"

Origin: Atkins diet; insulin hypothesis of obesity; overcorrection from low-fat era.

The myth: Carbohydrates uniquely cause weight gain and should be minimized or eliminated.

The truth:

• •Carbohydrates are the body's preferred fuel, especially for high-intensity exercise
• •Whole grain carbs are associated with better health outcomes
• •Refined carbs and added sugars are the problem, not carbs per se
• •Many healthy populations eat high-carb diets (Okinawa, traditional Asian diets)

Current understanding: Carb quality matters. Refined carbs and sugar are problematic; whole grains and vegetables are beneficial.

Evidence rating: ★★★★★ (Myth debunked; nuance needed)

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3. "Eating Frequently 'Boosts' Metabolism"

Origin: Thermic effect of food misunderstanding; bodybuilding lore.

The myth: Eating 6+ small meals per day "stokes the metabolic fire" and burns more calories.

The truth:

• •Thermic effect of food (TEF) is proportional to TOTAL food eaten, not meal frequency
• •3 meals of 600 kcal = 6 meals of 300 kcal for TEF purposes
• •Frequent eating may actually make it harder to control calories
• •Some people do better with fewer, larger meals

Current understanding: Meal frequency should be based on preference, schedule, and hunger. It doesn't affect metabolic rate.

Evidence rating: ★★★★★ (Myth debunked)

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4. "You Must Eat Within 30 Minutes Post-Workout" (The Anabolic Window)

Origin: Legitimate MPS research, then exaggerated by supplement marketing.

The myth: If you don't consume protein within 30 minutes of exercise, you "miss the window" and waste your workout.

The truth:

• •Muscle protein synthesis IS elevated post-exercise
• •But the "window" is much wider: 24-48 hours
• •If you ate pre-workout, the window is even less critical
• •Total daily protein matters more than precise timing

Current understanding: Eating within a few hours post-workout is sensible, but precise timing is not critical for most people.

Evidence rating: ★★★★☆ (Myth largely debunked; some nuance for multiple daily sessions)

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5. "Detox Diets Cleanse Toxins from Your Body"

Origin: Alternative medicine; marketing for cleanses and supplements.

The myth: Special diets, juices, or supplements remove accumulated "toxins" from the body.

The truth:

• •The body has sophisticated detoxification systems (liver, kidneys, lungs, skin)
• •These systems work continuously without dietary intervention
• •"Toxins" is vaguely defined and rarely specified
• •Juice cleanses are just very low-calorie diets
• •No scientific evidence that commercial detox products do anything

What actually helps: Not overwhelming your liver with excess alcohol, maintaining kidney function with adequate hydration, eating fiber to support elimination.

Evidence rating: ★★★★★ (Detox products are nonsense)

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6. "Starvation Mode" Prevents Weight Loss

Origin: Misunderstanding of metabolic adaptation; Minnesota Starvation Experiment lore.

The myth: If you eat too few calories, your body enters "starvation mode" and stops burning fat, preventing weight loss.

The truth:

• •Metabolic adaptation is real (5-15% reduction in expenditure beyond weight loss)
• •But it NEVER prevents weight loss—thermodynamics still applies
• •People in actual starvation continue losing weight
• •What happens: metabolism slows, hunger increases, NEAT decreases, making adherence harder

Current understanding: Aggressive deficits cause more adaptation and muscle loss. Sustainable deficits are better. But "starvation mode" stopping fat loss is a myth.

Evidence rating: ★★★★★ (Myth debunked; metabolic adaptation is real but different)

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7. "Breakfast Is the Most Important Meal of the Day"

Origin: Marketing by cereal companies (seriously); observational studies confounded by healthy user bias.

The myth: Skipping breakfast is unhealthy and causes weight gain.

The truth:

• •Randomized trials show no metabolic advantage to eating breakfast
• •People who eat breakfast may be generally healthier (confounding)
• •Some people function fine without breakfast
• •Intermittent fasting (skipping breakfast) can be effective for weight loss

Current understanding: Eat breakfast if you want to; skip it if you don't. No metabolic magic either way.

Evidence rating: ★★★★★ (Myth debunked)

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Legitimate Controversies (Science Is Unsettled)

1. Saturated Fat and Heart Disease

The debate: Does saturated fat cause heart disease?

Side A: Saturated fat raises LDL, LDL causes atherosclerosis, therefore saturated fat causes heart disease.

Side B: Some recent meta-analyses found no association between saturated fat and CVD. Maybe LDL particle size matters more.

Current state:

• •Saturated fat raises LDL (settled)
• •High LDL increases CVD risk (settled)
• •But: replacing saturated fat with refined carbs doesn't help
• •And: dairy fat may be less harmful than other sources
• •Individual variation exists

Practical guidance: Don't fear saturated fat completely, but choose unsaturated fats (olive oil, nuts, fish) as primary sources. Avoid replacing fat with refined carbs.

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2. Artificial Sweeteners

The debate: Are artificial sweeteners safe and helpful for weight management?

Concerns raised:

• •May increase sweet cravings
• •May alter gut microbiome
• •Possible metabolic effects
• •Epidemiological associations with obesity (reverse causality?)

Current evidence:

• •No convincing evidence of harm at normal consumption levels
• •May help reduce calorie intake when replacing sugar
• •Individual responses may vary
• •Long-term data limited

Practical guidance: Probably fine in moderation. Better than sugary drinks. But water is best.

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3. Organic vs. Conventional Produce

The debate: Is organic food healthier?

Arguments for organic:

• •Lower pesticide residues
• •Potentially higher antioxidant content
• •Environmental considerations
• •No synthetic fertilizers

Arguments against:

• •Pesticide levels on conventional produce are generally safe
• •Nutritional differences are small and inconsistent
• •Organic is more expensive
• •"Organic" doesn't mean pesticide-free

Current evidence:

• •No clear health benefit demonstrated in human studies
• •Pesticide exposure from conventional produce is very low
• •Environmental/ethical reasons are separate from health

Practical guidance: Eat more fruits and vegetables, regardless of organic status. If budget allows and you prefer organic, go for it. Don't avoid produce because you can't afford organic.

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4. Red Meat and Health

The debate: How harmful is red meat?

Concerns:

• •Processed meat is classified as carcinogenic (Group 1)
• •Red meat is "probably carcinogenic" (Group 2A)
• •Associated with colorectal cancer, CVD

Nuances:

• •Absolute risk increase is small
• •Quality and preparation matter
• •Grass-fed vs grain-fed may differ
• •Red meat provides valuable nutrients (iron, B12, zinc)

Current evidence:

• •Processed meat: limit significantly
• •Unprocessed red meat: moderate consumption (1-2x/week) probably fine
• •Very high consumption associated with increased risk

Practical guidance: Limit processed meat. Moderate red meat consumption is likely fine. Variety of protein sources is optimal.

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5. Gluten Sensitivity (Non-Celiac)

The debate: Is non-celiac gluten sensitivity real?

Arguments for:

• •Many people report symptom improvement on gluten-free diet
• •Gluten can affect gut permeability in some people
• •FODMAPs (often in gluten-containing foods) may be the real issue

Arguments against:

• •Blinded challenges often don't reproduce symptoms
• •Nocebo effect is powerful
• •May be FODMAPs, not gluten itself
• •Gluten-free diets may be lower quality

Current evidence:

• •Celiac disease is real and serious (1% of population)
• •True non-celiac gluten sensitivity probably exists but is rarer than claimed
• •FODMAPs may explain many cases
• •Blanket gluten avoidance is unnecessary for most

Practical guidance: If you suspect gluten issues, get tested for celiac disease. Try elimination and reintroduction. Don't assume gluten is the problem without evidence.

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Common Misconceptions (Not Quite Myths, But Oversimplified)

"Clean Eating"

The concept: Only eat "clean" whole foods; avoid anything processed or "unclean."

The problem:

• •"Clean" is undefined and moralistic
• •Creates food anxiety and orthorexic thinking
• •All-or-nothing mentality is unsustainable
• •Some "processed" foods are fine (canned beans, frozen vegetables)

Better approach: Emphasize whole foods (80%) with flexibility (20%). No food is morally "clean" or "dirty."

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"Superfoods"

The concept: Certain foods have exceptional health-promoting properties.

The problem:

• •Marketing term, not scientific category
• •Implies single foods are magical
• •Often expensive imported items when local options work fine
• •Overall diet matters more than any single food

Better approach: Eat a variety of nutrient-dense foods. No single food is essential or magical.

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"Eating for Your Blood Type"

The concept: Your blood type determines which foods you should eat.

The evidence: Zero scientific support. A large study found no association between blood type diets and health outcomes related to blood type.

Why it persists: Sounds scientific; book sold well; confirmation bias.

Status: Debunked pseudoscience.

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"Alkaline Diet"

The concept: Eating alkaline foods changes body pH and prevents disease.

The truth:

• •Body pH is tightly regulated (7.35-7.45)
• •Diet cannot meaningfully change blood pH
• •If it could, you'd die
• •Urine pH changes but is irrelevant to health
• •Foods recommended (vegetables, fruits) are healthy for other reasons

Status: Based on misunderstanding of physiology. The foods are fine; the mechanism is wrong.

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How to Evaluate New Nutrition Claims

Red flags:

• •Promises miracle results
• •Demonizes entire food groups
• •Relies on testimonials, not studies
• •Sells a product
• •Uses vague terms ("toxins," "natural," "clean")
• •Claims "doctors don't want you to know"
• •Based on single study or animal/cell research

Signs of reliability:

• •Acknowledges uncertainty and nuance
• •Based on systematic reviews and meta-analyses
• •Consistent with mainstream scientific organizations
• •Doesn't promise miracles
• •Considers dose and context

Practical Takeaways

• •Most nutrition "rules" are oversimplified: Reality is usually nuanced
• •Calories and protein: These fundamental factors explain most outcomes
• •Food quality matters: But not to the exclusion of quantity
• •Dietary pattern > individual foods: No superfoods, no poison foods
• •Context matters: What's good for one person may not be for another
• •Be skeptical of extremes: Truth is usually in the middle
• •Marketing ≠ science: Many claims are designed to sell products

Common Mistakes

Evidence Quality: Varies by topic

Thoroughly debunked: "Starvation mode," detox diets, meal frequency boosting metabolism, anabolic window urgency

Nuanced/context-dependent: Saturated fat, red meat, artificial sweeteners

Pseudoscience: Blood type diet, alkaline diet, most "superfoods" claims

Key References

• •Gardner CD, et al. (2018). Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss. JAMA. 319(7):667-679.
• •Johnston BC, et al. (2014). Comparison of weight loss among named diet programs in overweight and obese adults: a meta-analysis. JAMA. 312(9):923-933.
• •Schoenfeld BJ, et al. (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. Journal of the International Society of Sports Nutrition. 10:53.
• •Klein AV, Kiat H. (2015). Detox diets for toxin elimination and weight management: a critical review of the evidence. Journal of Human Nutrition and Dietetics. 28(6):675-686.

Executive Summary

Periodized nutrition matches fuel availability to training demands—providing carbohydrates when quality sessions require them while strategically restricting them to enhance fat adaptation. The key principle is "fuel for the work required." This approach optimizes both performance and metabolic adaptations, avoiding the extremes of chronic high-carb or chronic low-carb approaches.

Deep Dive

The Principle: Fuel for the Work Required

Not all training sessions have the same fueling needs:

Key insight: Chronically low-carb impairs high-intensity training. Chronically high-carb may limit metabolic flexibility. Periodization offers the best of both worlds.

Periodization Strategies

1. Sleep Low, Train Low

Protocol: Perform evening high-intensity session (depletes glycogen) → Skip carbs overnight → Perform morning aerobic session in depleted state

Benefits:

• •Enhanced fat oxidation adaptations
• •Increased mitochondrial biogenesis
• •Improved AMPK signaling

Drawbacks:

• •Cannot maintain high intensity in depleted state
• •May impair recovery if overused
• •Increases cortisol

Best for: Easy/moderate morning aerobic sessions following hard afternoon sessions

2. Train Low, Compete High

Protocol: Periodically train in low-glycogen state, but fully fuel for quality sessions and competition.

Implementation:

• •1-2 "train low" sessions per week
• •Fully fuel high-intensity sessions
• •Carb load for competition

Evidence: Studies show improved exercise economy and fat oxidation without performance detriment when used strategically.

3. Twice-a-Day Training

Protocol: Morning session depletes glycogen → Limit carb intake → Afternoon session in partially depleted state

Caution: Requires careful management to avoid overreaching.

Carbohydrate Periodization by Training Phase

Base/Aerobic Phase

Goal: Build aerobic capacity, enhance fat oxidation

Example day:

• •Morning: Easy 60-min run (fasted or light breakfast)
• •Breakfast: Moderate carbs + protein
• •Lunch: Balanced meal
• •Afternoon: Strength training (fueled)
• •Dinner: Moderate carbs + protein

Build/Intensity Phase

Goal: Develop race-specific fitness, handle high training load

Example day:

• •Pre-workout: Carb-rich breakfast (2-3 hours before)
• •Morning: Interval session (fueled)
• •Post-workout: Immediate recovery carbs + protein
• •Lunch: Carb-rich to continue recovery
• •Dinner: Moderate carbs + protein

Taper/Competition Phase

Goal: Peak glycogen stores, optimal performance

Carbohydrate Loading

Purpose: Maximize muscle and liver glycogen before endurance events >90 minutes.

Modern Protocol (3-Day)

Expected outcomes:

• •Muscle glycogen: 150-200+ mmol/kg wet weight (vs. ~100 normal)
• •Weight gain: 1-3 kg (glycogen + associated water)
• •Performance improvement: 2-3% in events >90 minutes

Food choices:

• •Low-fiber carbs: white rice, pasta, white bread, potatoes (no skin)
• •Fruit juice, sports drinks
• •Avoid: beans, high-fiber cereals, raw vegetables

During-Exercise Fueling

Carbohydrate Oxidation Rates

The body can only oxidize carbohydrates at limited rates:

Why multiple sources? Glucose and fructose use different intestinal transporters (SGLT1 and GLUT5). Using both increases total absorption capacity.

Fueling by Event Duration

Gut Training

The gut can be trained to tolerate higher carbohydrate intake:

Protocol:

• •Practice race nutrition during training
• •Progressively increase carb intake over 4-8 weeks
• •Train at race intensity while fueling
• •Use the exact products planned for competition

Evidence: Athletes who train their gut can tolerate and oxidize significantly more carbohydrate, improving performance.

Fat Adaptation

Concept: Extended periods of high-fat, low-carb diet to enhance fat oxidation capacity.

What Fat Adaptation Does:

• •Increases fat oxidation at given intensity
• •May spare glycogen during lower-intensity exercise
• •Enhances metabolic flexibility (theoretically)