Nutrition & hydration

2026-09-25

Day-to-day fueling for someone who lifts and runs: energy needs, macronutrients in g/kg, timing around training, carbohydrate loading, fluids and sodium, and the few supplements with good evidence. Race-day fueling is in endurance, fuel use by intensity in energy systems, and vitamins, minerals and iron in vitamins & minerals. Values are for healthy adults; see a doctor or a sports dietitian for anything clinical.

Energy balance

Total daily energy expenditure (TDEE) is basal metabolic rate (BMR) times a physical activity level (PAL). Weight is stable when intake matches TDEE.

BMR: Mifflin-St Jeor (1990)

$m$ body mass in kg, $h$ height in cm, $a$ age in years. Derived from 498 healthy adults aged 19–78 (normal weight and obese); it predicts resting needs, not an individual's exact value.

\text{BMR}_\text{men} = 10\,m + 6.25\,h - 5\,a + 5 \qquad \text{BMR}_\text{women} = 10\,m + 6.25\,h - 5\,a - 161 \quad (\text{kcal/day})

If you know fat-free mass (FFM), the same paper gives $\text{REE} = 19.7\,\text{FFM} + 413$ .

Activity factor (PAL)

\text{TDEE} = \text{BMR} \times \text{PAL}

Lifestyle (FAO/WHO/UNU 2001)	PAL	Example
sedentary or light activity	1.40–1.69	desk job, little exercise
active or moderately active	1.70–1.99	desk job plus ~1 h/day running or lifting
vigorous	2.00–2.40	manual job or 2+ h/day hard training

PAL above 2.40 is hard to sustain for long. Watches and apps estimate exercise energy with large errors; treat any TDEE as a starting point and adjust from 2–3 weeks of body-mass trend.

Energy per gram

Nutrient	kcal/g	kJ/g
carbohydrate	4	17
protein	4	17
fat	9	37
alcohol	7	29

Energy availability and REDs

Energy availability (EA) is the energy left for the rest of the body after exercise, per kg of fat-free mass.

\text{EA} = \frac{\text{EI} - \text{EEE}}{\text{FFM}} \quad (\text{kcal/kg FFM/day})

EI is energy intake, EEE exercise energy expenditure. Low EA (LEA) drives REDs (Relative Energy Deficiency in Sport, formerly RED-S): hormonal, bone, immune, metabolic and mental-health effects plus worse training and performance, in women and men.

EA (kcal/kg FFM/day)	Reading (Loucks' reference bands from lab studies in sedentary women; IOC 2023 plays them down)
≥ 45	enough for maintenance and normal body function
30–45	reduced; typical of deliberate fat loss
≤ 30	LEA with health effects in the original studies
~9–25	range where men appear to show effects

Caveat (IOC 2023)	Detail
not a diagnostic cut-off	30 came from short-term lab studies in small groups of sedentary women; meant as a guide
individual differences	the EA that causes problems varies between people, sexes and body systems
measurement error	EI, EEE and FFM are all hard to measure in free-living athletes
red flags beat numbers	missed or absent periods, low libido, recurrent bone stress injury, illness, stalled training, low mood

Macronutrients

Targets scale with body mass and training load, not with a fixed percentage of energy.

Carbohydrate by training load (ACSM/AND/DC 2016)

Load	Example	g/kg/day	70 kg runner
light	low intensity or skill work	3–5	210–350 g
moderate	~1 h/day moderate exercise	5–7	350–490 g
high	1–3 h/day moderate to high intensity	6–10	420–700 g
very high	over 4–5 h/day moderate to high intensity	8–12	560–840 g

These are for days when session quality matters. Easy days and fat-loss phases can sit lower; some athletes deliberately train with low carbohydrate availability for specific sessions.

Protein

Guideline	Value	Source
daily, most exercisers	1.4–2.0 g/kg	ISSN 2017
daily, joint statement	1.2–2.0 g/kg	ACSM/AND/DC 2016
point of diminishing returns for muscle gain	~1.6 g/kg (upper CI ~2.2)	Morton et al. 2018 meta-analysis
per meal	0.25–0.4 g/kg, or 20–40 g	ISSN nutrient timing 2017
leucine per dose	700–3,000 mg	ISSN 2017
spacing	every 3–4 h across the day	ISSN 2017
before sleep	30–40 g casein	ISSN 2017
energy deficit	higher, see body composition	Helms 2014, ISSN 2017

Fat

Guideline	Value	Source
usual range	20–35% of energy	ACSM/AND/DC 2016
avoid chronically	under 20% of energy: harder to meet fat-soluble vitamin and essential fatty acid needs	ACSM/AND/DC 2016
before and during hard sessions	keep fat and fiber low for gut comfort	ACSM/AND/DC 2016

Watch for: carbohydrate periodised to the session, protein spread through the day, practical meals.

*Sports Nutrition - Presented by Louise Burke* (opens in a new tab) (Athletics Coach, YouTube)

Nutrient timing

When	What	Amount
2–4 h before	fluid to pale urine	5–10 mL/kg
1–4 h before (sessions over 60 min)	carbohydrate-rich meal, low in fat, fiber and protein	1–4 g/kg
under 45 min exercise	nothing needed	none
45–75 min, high intensity	small amounts or a carbohydrate mouth rinse	small
1–2.5 h	carbohydrate	30–60 g/h
over 2.5–3 h	glucose + fructose mixes	up to 90 g/h
under 8 h between two hard sessions	carbohydrate, early and often	1.0–1.2 g/kg/h for 4 h
after a key session	high-quality protein	0.25–0.3 g/kg (15–25 g)

Amounts from ACSM/AND/DC 2016; race-day plans are in endurance.

The anabolic window

Claim	Evidence
protein 0–2 h after lifting boosts muscle protein synthesis	true (ISSN 2017)
you must eat within 30–60 min or lose gains	overstated: muscle stays sensitive to protein for at least 24 h
timing matters when daily protein is adequate	at best minimal (ISSN 2017; Aragon and Schoenfeld 2013)
timing matters for glycogen	yes, when the next hard session is under 8 h away
training fasted in the morning	eat protein soon after; the pre-meal gap is already long

Carbohydrate loading

For events over 90 min of sustained or intermittent work (marathon, long triathlon), fill glycogen beforehand. For shorter races, normal daily fueling (7–12 g/kg in the 24 h before) is enough.

Item	Guideline (ACSM/AND/DC 2016)
amount	10–12 g/kg/day
duration	36–48 h before the event
training	taper at the same time
food choice	low fiber and low residue: white bread, rice, pasta, juice, jam, honey
side effect	body mass rises because glycogen is stored with water
practice	trial it before a long training run, never first on race week

Body composition

Goal	Guideline	Source
fat loss: deficit	~250–500 kcal/day below needs	ACSM/AND/DC 2016
fat loss: rate	0.5–1% body mass per week	Helms et al. 2014
fat loss: rate to protect FFM and performance	under 1% body mass per week	ACSM/AND/DC 2016
fat loss: protein	2.3–3.1 g/kg fat-free mass	Helms et al. 2014; ISSN 2017
fat loss: fat	15–30% of energy	Helms et al. 2014
muscle gain: surplus	~10–20% above maintenance	Iraki et al. 2019
muscle gain: rate (novice, intermediate)	~0.25–0.5% body mass per week; slower if advanced	Iraki et al. 2019
muscle gain: protein	1.6–2.2 g/kg	Iraki et al. 2019
muscle gain: fat	0.5–1.5 g/kg	Iraki et al. 2019

Keep EA well above 30 kcal/kg FFM/day while cutting, and time deficits for easier training blocks, not race build-ups.

Hydration

Daily needs

Total water includes drinks and the water in food, for temperate climates and moderate activity. Training and heat add sweat losses on top.

Source	Men	Women
NASEM AI (total water, 19–50 y)	3.7 L/day	2.7 L/day
EFSA AI (total water, adults)	2.5 L/day	2.0 L/day

Sweat rate

\text{sweat rate (L/h)} = \frac{(m_\text{pre} - m_\text{post}) + V_\text{drunk} - V_\text{urine}}{t}

Masses in kg (1 kg ≈ 1 L sweat), volumes in L, $t$ in hours. Weigh nude or in the same dry kit, bladder empty before, towel dry after.

Quantity	Typical value	Source
sweat rate	0.5–2.0 L/h; 0.3–2.4 L/h reported	Baker 2017; ACSM/AND/DC 2016
sweat sodium	~50 mmol/L (~1 g/L) average; 10–90 mmol/L range	ACSM/AND/DC 2016; Baker 2017

Guidelines

Phase	Guideline	Source
before	5–10 mL/kg 2–4 h before, until urine is pale yellow	ACSM/AND/DC 2016
during	drink to keep the loss under 2% of body mass	ACSM 2007; ACSM/AND/DC 2016
during	never drink so much that you gain weight	ACSM/AND/DC 2016
after	1.25–1.5 L per kg lost (125–150% of the deficit), with sodium, spread over time	ACSM/AND/DC 2016
check	pale-yellow urine and a steady morning body mass	ACSM/AND/DC 2016

Urine color is a rough guide only: a large drink dilutes it quickly. Caffeine does not cause extra urine or sweat loss during exercise (ODS).

Sodium, electrolytes and hyponatraemia

Point	Detail
who needs sodium during exercise	sweat rate over 1.2 L/h, salty sweat, or sessions over 2 h (ACSM/AND/DC 2016)
after exercise	don't restrict sodium; it helps you keep the fluid you drink
units	1 mmol sodium = 23 mg; salt (NaCl) = 2.5 × sodium
compare products	check mg sodium per liter on the label against ~1,000 mg/L average sweat loss
cramp	usually fatigue; heavy salty sweaters in the heat may be more prone (ACSM/AND/DC 2016)

Exercise-associated hyponatraemia

Blood sodium under 135 mmol/L, mostly from drinking more than you sweat, made worse by large sodium losses and plain water.

Risk factors (ACSM/AND/DC 2016)	Symptoms, mostly below 130 mmol/L
recreational pace: low sweat rate, many chances to drink	bloating, puffiness, weight gain during the event
smaller body and lower sweat rate (women more often)	nausea, vomiting, headache
drinking beyond sweat and urine losses	confusion, delirium, seizures
overdrinking in the hours or days before	respiratory distress, collapse; can be fatal

Watch for: how researchers measure sweat rate and why over-drinking is the bigger danger for recreational runners.

*Hydration and Athletic Performance with Dr. Stavros Kavouras* (opens in a new tab) (Jordan Sullivan Dietitian, YouTube)

Caffeine and creatine

Caffeine

Item	Value	Source
effective dose	3–6 mg/kg (210–420 mg at 70 kg)	ISSN 2021; IOC 2018
lowest effective dose	maybe 2 mg/kg	ISSN 2021
timing	~60 min before; gum works faster	ISSN 2021
peak and half-life	peak within ~45 min; half-life 4–5 h	ODS
very high doses	9 mg/kg: many side effects, no extra benefit	ISSN 2021
side effects	anxiety, jitters, fast heart rate, gut upset, poor sleep	ISSN 2021; FDA
general daily limit	400 mg/day for most healthy adults	FDA
brewed coffee	113–247 mg per 355 mL (12 fl oz)	FDA
pure powder	about 1,200 mg can cause seizures; don't use powders	FDA
habitual users	benefit still seen; no need to withdraw	ISSN 2021

With a 4–5 h half-life, afternoon and evening doses can disturb sleep (ODS).

Creatine monohydrate

Item	Value	Source
maintenance	3–5 g/day	ISSN 2017; IOC 2018
optional loading	~0.3 g/kg/day (~20 g in 4 doses) for 5–7 days	ISSN 2017; IOC 2018
no loading	3–5 g/day fills muscle in 3–4 weeks	ISSN 2017
works for	repeated high-intensity efforts, strength and power, training volume	IOC 2018; ODS
endurance running	little direct benefit; weight gain can hurt	ODS
side effect	+1–2 kg body mass, mainly water	IOC 2018
safety	safe long term in healthy adults (studies up to 5 years)	ISSN 2017

Supplements: what has evidence

Food first. Supplements are for a confirmed deficiency, convenience, or one of a few performance aids, and carry a doping risk from contamination (see third-party testing).

Performance supplements with good evidence (IOC 2018)

Supplement	Protocol	Helps	Watch
caffeine	3–6 mg/kg ~60 min before	endurance (5–150 min), 1–2 min efforts, repeated sprints	nausea, anxiety, insomnia
creatine	3–5 g/day (loading optional)	strength, single and repeated efforts under 150 s	1–2 kg gain
nitrate (beetroot juice)	5–9 mmol (310–560 mg) 2–3 h before	time trials under 40 min, 12–40 min team sport	occasional gut upset
beta-alanine	~65 mg/kg/day in 0.8–1.6 g doses every 3–4 h for 10–12 weeks	efforts of 30 s to 10 min (~0.2–3%)	tingling, rash
sodium bicarbonate	0.2–0.4 g/kg 60–150 min before	sprints of ~60 s; less benefit past 10 min	gut distress, lots of sodium

AIS Sports Supplement Framework, Group A

Group A type	Examples
sports foods	sports drinks, gels, bars, confectionery, electrolyte supplements, protein powders, liquid meals
medical supplements	iron, calcium, vitamin D, zinc, folate (only for a diagnosed need)
performance supplements	caffeine, beta-alanine, nitrate, sodium bicarbonate, creatine, glycerol

Group	Meaning	Examples
B	emerging or mixed evidence; use in research or clinical monitoring	vitamin C, fish oil, collagen, probiotics, tart-cherry polyphenols
C	evidence not supportive, or no research	BCAAs, vitamin E, magnesium oxide, HMB, tyrosine
D	banned or high contamination risk; don't use	DMAA, ephedrine, DHEA, SARMs such as ostarine

Alcohol and recovery

Effect	Detail	Source
energy	7 kcal/g, suppresses fat oxidation, prompts unplanned eating	ACSM/AND/DC 2016
before or during training	worse metabolism, thermoregulation and skill; effects outlast feeling drunk	ACSM/AND/DC 2016
glycogen	impairs refuelling after exercise	ACSM/AND/DC 2016
rehydration	suppresses antidiuretic hormone, so more urine	ACSM/AND/DC 2016
muscle protein synthesis	1.5 g/kg (~12 drinks) after training cut it 24% with protein, 37% with carbohydrate	Parr et al. 2014
cold	peripheral vasodilation, heat loss	ACSM/AND/DC 2016
practical	minimize alcohol after key sessions and when injured; eat protein and carbohydrate first	ACSM/AND/DC 2016

Food labels

US Nutrition Facts

Item	Rule (FDA)
serving size	every number is per serving; multiply if you eat more
%DV basis	2,000 kcal/day general guide; athletes often eat more
5% DV or less	low in that nutrient
20% DV or more	high in that nutrient
get less of	saturated fat, sodium, added sugars
get more of	fiber, vitamin D, calcium, iron, potassium

US Nutrition Facts label (2016 format) for a cereal: 8 servings, serving 2/3 cup (55 g), 230 calories, total fat 8 g, sodium 160 mg, carbohydrate 37 g with 4 g fiber and 10 g added sugars, protein 3 g, plus vitamin D, calcium, iron and potassium with % Daily Value Image: U.S. Food and Drug Administration, public domain, via Wikimedia Commons (opens in a new tab).

UK front-of-pack colors (per 100 g)

Nutrient	Low (green)	High (red)
total fat	≤ 3 g	over 17.5 g
saturated fat	≤ 1.5 g	over 5 g
total sugars	≤ 5 g	over 22.5 g
salt	≤ 0.3 g	over 1.5 g (0.6 g sodium)

Amber sits between the two. For training, "red" carbohydrate or sugar can be exactly what you want before or during a long session.

Recipes

TDEE and macros for a 70 kg runner

A worked day for a 30-year-old man, 178 cm, ~15% body fat, running about an hour a day plus two lifting sessions a week.

BMR  = 10(70) + 6.25(178) - 5(30) + 5    = 1,668 kcal
PAL  = 1.75 (active)
TDEE = 1,668 x 1.75                        ≈ 2,920 kcal
 
Carbohydrate  6 g/kg x 70  = 420 g  x 4 = 1,680 kcal  (58%)
Protein     1.6 g/kg x 70  = 112 g  x 4 =   448 kcal  (15%)
Fat         remainder      =  88 g  x 9 =   790 kcal  (27%, 1.25 g/kg)
 
Energy availability check
FFM  = 70 x 0.85 = 59.5 kg;  EEE (watch) ≈ 700 kcal
EA   = (2,920 - 700) / 59.5 ≈ 37 kcal/kg FFM/day   (above 30: fine)
 
Protein per meal: 0.3 g/kg ≈ 21 g, x 4 meals + 28 g evening
Same runner, 60 kg woman, 165 cm: BMR = 1,320 kcal

Check the body-mass trend after 2–3 weeks and adjust, and move carbohydrate up on long-run days (6–10 g/kg) and down on rest days (3–5 g/kg).

Pre-race breakfast

For a 70 kg runner racing at 09:00: ~2 g/kg carbohydrate 3 h before, low fat and fiber. Values from USDA FoodData Central.

Time	Food	Carbohydrate
06:00	white toast, 120 g (about 4 slices)	65 g
06:00	jam, 40 g	28 g
06:00	banana, 120 g peeled	27 g
06:00	honey in tea or on toast, 20 g	16 g
06:00–07:00	water or electrolyte drink, 350–700 mL (5–10 mL/kg)	–
08:40	optional: a gel or a few sips of sports drink (check the label)	–
total	~12 g protein, ~5 g fat, ~630 kcal	~137 g (2.0 g/kg)

Only 1 h before? Halve it: 2 bananas (240 g) and 20 g honey give ~71 g (1 g/kg). Use foods you have tested in training.

Marathon carb-load day

One of the two days before a marathon: 10 g/kg for a 70 kg runner is 700 g carbohydrate. Low fiber on purpose; USDA values, cooked weights.

Meal	Foods	Carbohydrate
breakfast	white toast 150 g, jam 40 g, honey 20 g, banana 120 g, 2% milk 300 mL	168 g
snack	2 bananas (240 g), Greek yogurt 170 g, honey 30 g	85 g
lunch	white rice 450 g, white toast 60 g	160 g
snack	white toast 100 g, jam 40 g	82 g
dinner	pasta 500 g with tomato sauce, white toast 60 g	186 g
evening	2% milk 300 mL, honey 20 g	31 g
total	~115 g protein (1.6 g/kg), ~35 g fat, ~3,600 kcal	712 g (10.2 g/kg)

Swap in juice, rice cakes, sports drink or sweets if the volume is too much. Keep salt normal and drink to thirst.

Sweat-rate test

Run it in race-like conditions; repeat in hot and cool weather.

Empty your bladder, weigh nude: record $m_\text{pre}$ .
Train 60–90 min at race effort; weigh bottles before and after (1 g = 1 mL) to get $V_\text{drunk}$ .
Don't pee during the session, or measure it: $V_\text{urine}$ .
Towel dry, weigh nude: $m_\text{post}$ .
Compute sweat rate and % body mass lost.

m_pre 70.0 kg, m_post 68.9 kg, drank 0.5 L, urine 0, 75 min
 
Sweat loss = (70.0 - 68.9) + 0.5 - 0 = 1.6 L
Sweat rate = 1.6 L / 1.25 h           = 1.28 L/h
Mass lost  = 1.1 / 70.0               = 1.6 %   (under 2 %)
Rehydrate  = 1.1 kg x 1.25-1.5        = 1.4-1.65 L, with salt
Sodium     = 1.6 L x ~1 g/L           ≈ 1.6 g lost (average sweat)

Plan to drink enough to stay under 2% loss, not to replace every milliliter; if you gained mass, drink less.

Post-workout snacks

Aim for 0.25–0.3 g/kg protein (18–21 g at 70 kg). Add carbohydrate at 1.0–1.2 g/kg/h if the next hard session is under 8 h away. USDA values.

Snack	Protein	Carbohydrate	Best for
Greek yogurt 200 g, banana 120 g, honey 20 g	20 g	51 g	after lifting
2% milk, 600 mL	20 g	30 g	quick, portable (chilled)
white toast 100 g, jam 30 g, 2% milk 400 mL	23 g	95 g	two sessions in a day
pasta 300 g cooked, 2% milk 250 mL	26 g	104 g	after a long run

Daily plate template

The Athlete's Plate (USOPC and UCCS) scales the carbohydrate share of each meal to the day's training.

Day	Grains and starches	Vegetables and fruit	Lean protein
easy, taper or fat loss	~25%	~50%	~25%
moderate (your baseline)	~37.5%	~37.5%	~25%
hard, race or carb-load	~50%	~25%	~25%

Every plate adds a small fat portion (about 1 tablespoon of oil, nuts, seeds, avocado or cheese), a drink (water, milk or a dairy alternative) and flavourings. Three or four plates like this, each with protein, cover most days.

References

Thomas, Erdman and Burke: Nutrition and Athletic Performance, ACSM/AND/DC joint position (2016) (opens in a new tab): carbohydrate, protein, fat, EA, timing, carbohydrate loading, fluids, alcohol
Mifflin et al.: A new predictive equation for resting energy expenditure (1990) (opens in a new tab): the BMR equations
FAO/WHO/UNU: Human energy requirements (2001, pub. 2004) (opens in a new tab): PAL categories
FAO: Food energy, methods of analysis and conversion factors (2003) (opens in a new tab): Atwater factors
Mountjoy et al.: 2023 IOC consensus statement on REDs (opens in a new tab): EA continuum, the 30 kcal/kg FFM caveats, male ranges
Jäger et al.: ISSN position stand, protein and exercise (2017) (opens in a new tab): daily and per-dose protein, leucine, deficit protein
Kerksick et al.: ISSN position stand, nutrient timing (2017) (opens in a new tab): the anabolic window, per-meal protein
Aragon and Schoenfeld: Nutrient timing revisited (2013) (opens in a new tab): post-exercise window evidence
Morton et al.: Protein supplementation and resistance training meta-analysis (2018) (opens in a new tab): 1.6 g/kg breakpoint
Helms, Aragon and Fitschen: Natural bodybuilding contest preparation (2014) (opens in a new tab): rate of loss, protein and fat in a deficit
Iraki et al.: Nutrition for bodybuilders in the off-season (2019) (opens in a new tab): surplus, gain rate, protein and fat
Sawka et al.: ACSM position stand, Exercise and fluid replacement (2007) (opens in a new tab): the 2% body-mass-loss guideline, individual sweat testing
Baker: Sweat testing methodology in the field, GSSI SSE 161 (2017) (opens in a new tab): sweat rate formula, sweat and sodium ranges
NASEM: DRI table, total water and macronutrients (opens in a new tab): total water AI 3.7 and 2.7 L
EFSA: Dietary reference values for water (2010) (opens in a new tab): total water AI 2.5 and 2.0 L
Guest et al.: ISSN position stand, caffeine and exercise performance (2021) (opens in a new tab): dose, timing, side effects
Kreider et al.: ISSN position stand, creatine (2017) (opens in a new tab): loading, maintenance, safety
Maughan et al.: IOC consensus statement on dietary supplements (2018) (opens in a new tab): evidence-graded performance supplements and protocols
AIS: Sports Supplement Framework, Group A (opens in a new tab): ABCD classification
NIH ODS: Dietary supplements for exercise and athletic performance (opens in a new tab): caffeine kinetics, creatine, bicarbonate, antioxidants
FDA: Spilling the beans, how much caffeine is too much? (opens in a new tab): 400 mg/day, coffee content, powder warning
Parr et al.: Alcohol ingestion impairs post-exercise myofibrillar protein synthesis (2014) (opens in a new tab): alcohol and recovery
FDA: How to understand and use the Nutrition Facts label (opens in a new tab): %DV, 5/20 rule
NHS: How to read food labels (opens in a new tab): UK traffic-light thresholds
USDA FoodData Central (opens in a new tab): per-100 g values used in the recipes
USOPC and UCCS: The Athlete's Plate (handout) (opens in a new tab): easy, moderate and hard plates