how many carbs should i eat before a marathon?

for the last 36-48 hours, about 10-12 g of carbohydrate per kg of body weight a day: 600-720 g a day for a 60 kg runner, spread over 5-6 meals and snacks. on race morning, ~2 g/kg about 3 hours before the start (~120 g for 60 kg), low in fibre and fat. if that feels like too much, start at 8 g/kg and build up across races.

what should i eat before a 10k or 5k?

something light and familiar: 2 idlis, toast + jam or a banana about 60-90 minutes out, or a normal breakfast 2-3 hours before. sip some fluid from waking to the start. running a short race fasted is fine for most healthy runners.

how much sodium do i need while running in india's heat?

about 0.5-0.7 g of sodium per litre of fluid you plan to drink on runs over an hour. salty sweaters (white salt lines on clothes or cap) aim for the upper end, around 500-700 mg an hour. drink to your sweat rate or to thirst, never beyond it: over-drinking plain water causes hyponatremia.

how much caffeine before running?

start at 1-3 mg per kg of body weight about 60 minutes before the start: 60-180 mg for a 60 kg runner, roughly 1-2 strong coffees. the studied range is 3-6 mg/kg, but benefits tend to plateau around 3 mg/kg, and more is not better. never try it for the first time on race day.

is this medical advice?

no. it is general education from published sports-nutrition research, and every number is an approximate starting range. if you have diabetes, kidney, heart or blood-pressure conditions, are pregnant, or have a history of disordered eating, talk to your doctor or a registered dietitian before changing how you eat and drink around running.

Carb Loading & Race Fuel Calculator India

The race fuel calculator + carb loading calculator

a race fuel calculator and a runner diet plan for india in one card. three answers give you a race plan; the everyday questions below give you your calories and protein. it updates as you tap. the why behind every number is in The Runner's Fuel Guide. need the training side too? the workout plan builder builds your week.

general education, not medical advice. every number is an approximate starting range. with diabetes, kidney, heart or blood-pressure conditions, talk to your doctor first. nothing new on race day. your answers stay on this device.

Your daily meals

A simple Indian day provides about 114 g of protein across three eating occasions: breakfast around 40 g, lunch around 37 g, dinner around 37 g. This is one illustrative example, not a prescription. More in the everyday plate, in the fuel guide, or the printable PDF.

this week's prep checklist

boil 8-10 eggs
cook the dal, soya or rajma-chana batch
portion soya chunks and oats into daily servings
set tonight's milk for curd
pack tomorrow's office meals the night before

ticks stay on this device only - no account, nothing sent anywhere.

What to eat before a 10k or 5k

10k under 60 minutes nutrition, honestly: almost nothing special.

under ~75 minutes your glycogen tank outlasts the race, so a 5k or 10k needs no carb load, no gels and no electrolyte drink on a normal day. eat a normal dinner with carbs, then something light and familiar 60-90 minutes out (2 idlis, toast + jam or a banana), and drink water to thirst. nobody ever carb-loaded their way under 60 minutes in the 10k: the runners who break 60 eat normal dinners, sleep well, and train for months.

the short-race question: 5k & 10k, in the fuel guide

Carb loading, day by day

eating 10-12 g of carbohydrate per kg a day for the last 36-48 hours pushes your glycogen stores well above normal. it pays for races over about 90 minutes.

5k and 10k: none needed. half marathon: normal carb-rich eating covers most runners; an extra carb-focused day can help a long or hard race. marathon: 2 full days. eat low fibre, low fat staples - rice, idli, poha, bread, banana, potato - spread over 5-6 meals and snacks, and start with 8 g/kg if the full load feels like too much.

more in the guide: the full loading plan, clean carbs and a sample 2-day load

Just before the race

top off the tank, calm the gut, start hydrated.

the main meal 3-4 h out: 1-4 g/kg of low-fibre, low-fat carbs (white bread + jam + banana, or idli + honey) and 5-7 ml/kg of fluid. an early start? eat a smaller version (~1 g/kg) 60-90 minutes out. nothing you have not eaten before a training run.

this calculator is free and so is the club. come say hi on r/punerunners or @punerunnersclub on instagram.

more in the guide: race morning, the 4 am gut routine and race week

During the race · pocket fuel

under ~75 min: little or none. 1 to 2.5 h: 30-60 g/h. over 2.5 h: build towards 60-90 g/h, as glucose + fructose together.

a gel is ~22-25 g of carbs, a banana ~25 g, 4 dates ~28 g. anything you race with must be something your gut has already met on long training runs.

more in the guide: the pocket-fuel table and the 4-week gut training plan

How we calculate this

no black box - check every number by hand. worked example: 60 kg runner, marathon in 4:30, hot & humid race, salty sweater.

every formula the calculator uses, with a worked example
step	formula	worked example
daily calories	BMR (Mifflin-St Jeor) x activity factor (1.4-1.9), then goal: -300 to -500 (lose) / 0 (perform) / +200-300 (build)	1528 x 1.6 = ~2450 kcal to maintain
protein	master table: 1.2-1.6 recreational · 1.4-1.8 run + strength · 1.6-2.0 strength focus	72-96 g/day recreational
carb load	weight x 10-12 g/kg/day, last 36-48 h	60 x 10-12 = 600-720 g/day
race-morning meal	1-4 g/kg, 1-4 h before	~2 g/kg at 3 h out = ~120 g
pre-race fluid	5-7 ml/kg with the meal	300-420 ml
in-race carbs	<75 min: little/none · ~1-2.5 h: 30-60 g/h · >~2.5 h: build towards 60-90 g/h where appropriate	4:30 race = 60-90 g/h, gut-trained
sweat rate	((weight before - weight after) x 1000 + ml drunk) / hours	(1.0 x 1000 + 500)/1 = 1500 ml/h
race fluid	400-800 ml/h, scaled by sweat test, never above sweat rate	hot day = 500-800 ml/h
sodium	0.5-0.7 g per litre of planned fluid; salty sweaters aim higher	~0.6 L/h x 0.5-0.7 = 300-420; salty: aim 500-700 mg/h at ~1 L/h
caffeine	1-3 mg/kg to start (studied 3-6), ~60 min before	60-180 mg to start; most runners stay at or under ~180 mg
recovery	rapid turnaround (<8 h to next hard session): 1.0-1.2 g/kg carbs/h + 0.25-0.3 g/kg protein early; fluid ~1.25-1.5x losses with sodium	~60-72 g carbs/h + ~15-18 g protein (rapid days)

the daily numbers use the middle of each range: activity x 1.45 (light) / 1.6 (4-5 days) / 1.8 (heavy), and goal -400 (lose) / 0 / +250 (build). calories never go below 1500 (men) or 1200 (women). protein follows the training focus you pick from the master table: 1.4 / 1.6 / 1.8 g/kg.

sweat rate calculator: the 1-hour sweat test

weigh in: dry, minimal clothes, right before a 1-hour run at race pace. write it down.
run: track exactly how much you drink, in ml.
weigh out: towel off, weigh again, same conditions.
calculate: sweat rate = (kg lost x 1000 + ml you drank) / hours run. every 1 kg = 1 litre of sweat.
repeat in race-like weather: heat and humidity change the number a lot. pune runners should test on a warm morning, not a cool one.

example: 60.0 kg before, 59.0 kg after, 500 ml drunk in 1 hour = (1.0 x 1000 + 500) / 1 = 1500 ml/h. your race fluid plan should replace a good share of that - not all of it - and never so much that you finish heavier than you started. plan first; thirst fine-tunes. got your number? pick "i measured my sweat rate" under fine-tune your plan in the calculator.

am i a salty sweater?

white salt lines on clothes or cap brim, sweat that stings your eyes, gritty skin after a run: that's high sweat sodium. field data from 30,000+ athlete sweat tests puts the average near ~950 mg per litre with roughly a ten-fold spread, and your number is mostly genetic and stable. salty sweaters use the upper end of the sodium ranges.

hyponatremia: drinking far more plain water than you sweat dilutes blood sodium. mild cases cause nausea, headache, confusion; severe cases are life-threatening. know your sweat rate, drink to plan or to thirst, include sodium on long hot runs, and never force-drink beyond your losses.

hydration and the sweat test, in the fuel guide

the long read

The Runner's Fuel Guide

everything behind the calculator, written for indian kitchens and indian weather: the everyday plate, the protein kitchen with four day plans, calories by hand, gym and hyrox days, carb loading, race morning, the 5k & 10k question, hydration, recovery, caffeine, graded supplements, gut training, race week, away races and the sources. free, on the web or as a PDF.

Read the fuel guide Download the PDF

Questions runners ask

how many carbs should i eat before a marathon?: for the last 36-48 hours, about 10-12 g of carbohydrate per kg of body weight a day: 600-720 g a day for a 60 kg runner, spread over 5-6 meals and snacks. on race morning, ~2 g/kg about 3 hours before the start (~120 g for 60 kg), low in fibre and fat. if that feels like too much, start at 8 g/kg and build up across races.
do i need to carb load or carry gels for a 10k under 60 minutes?: no. your glycogen tank outlasts ~75 minutes of hard running, so a 5k or 10k needs no carb load, no gels and no electrolyte drink on a normal day. eat a normal dinner with carbs, drink water to thirst, and save the loading menus for races over about 90 minutes.
what should i eat before a 10k or 5k?: something light and familiar: 2 idlis, toast + jam or a banana about 60-90 minutes out, or a normal breakfast 2-3 hours before. sip some fluid from waking to the start. running a short race fasted is fine for most healthy runners.
how much sodium do i need while running in india's heat?: about 0.5-0.7 g of sodium per litre of fluid you plan to drink on runs over an hour. salty sweaters (white salt lines on clothes or cap) aim for the upper end, around 500-700 mg an hour. drink to your sweat rate or to thirst, never beyond it: over-drinking plain water causes hyponatremia.
how much caffeine before running?: start at 1-3 mg per kg of body weight about 60 minutes before the start: 60-180 mg for a 60 kg runner, roughly 1-2 strong coffees. the studied range is 3-6 mg/kg, but benefits tend to plateau around 3 mg/kg, and more is not better. never try it for the first time on race day.
is this medical advice?: no. it is general education from published sports-nutrition research, and every number is an approximate starting range. if you have diabetes, kidney, heart or blood-pressure conditions, are pregnant, or have a history of disordered eating, talk to your doctor or a registered dietitian before changing how you eat and drink around running.

too many numbers? the whatsapp community is where the real chatter lives. punerunners.com has the join link. bring a friend, we're friendly.

The research

the same sources as the guide, numbered the same way. carb plans stay capped at 90 g/h even though elites report more [12].

Burke, Hawley, Wong & Jeukendrup, "Carbohydrates for training and competition", Journal of Sports Sciences (2011) - carb loading 10-12 g/kg/day, 36-48 h; daily carb targets. doi:10.1080/02640414.2011.585473 (opens in a new tab)
German Nutrition Society (DGE) Sports Nutrition Working Group position (2020), German Journal of Sports Medicine - loading recommended for events over ~90 min. germanjournalsportsmedicine.com (opens in a new tab)doi:10.5960/dzsm.2020.456 (opens in a new tab)
Thomas, Erdman & Burke - ACSM / Academy of Nutrition and Dietetics / Dietitians of Canada position stand, Nutrition and Athletic Performance (2016): 30-60 g/h, up to 90 g/h; protein 1.2-2.0 g/kg. doi:10.1249/MSS.0000000000000852 (opens in a new tab)
Jeukendrup, "A Step Towards Personalized Sports Nutrition", Sports Medicine (2014) - duration-based carb intake, glucose+fructose absorption ceiling, gut training. PMC4008807 (opens in a new tab)
Australian Institute of Sport position statements - sports drink composition, electrolyte replacement (0.5-0.7 g sodium/L), and the supplement grading framework (A/B/C/D) behind sections 09 and 13c. ausport.gov.au/ais/nutrition (opens in a new tab)
Guest et al., International Society of Sports Nutrition position stand: caffeine and exercise performance (2021) - 3-6 mg/kg. doi:10.1186/s12970-020-00383-4 (opens in a new tab)
Jentjens & Jeukendrup, "Determinants of post-exercise glycogen synthesis during short-term recovery", Sports Medicine (2003), and subsequent recovery reviews - 1.2 g/kg/h carbs and protein co-ingestion. doi:10.2165/00007256-200333020-00004 (opens in a new tab)
Hew-Butler et al., statement of the third international exercise-associated hyponatremia consensus (2015) - over-drinking as the primary cause; drink to plan or thirst. doi:10.1097/JSM.0000000000000221 (opens in a new tab)
University of Washington Medicine sports hydration guidance - sweat-rate test protocol, 400-800 ml/h starting range. rightasrain.uwmedicine.org (opens in a new tab)
Mifflin-St Jeor, "A new predictive equation for resting energy expenditure in healthy individuals", Am J Clin Nutr (1990). doi:10.1093/ajcn/51.2.241 (opens in a new tab)
Mountjoy et al., IOC consensus on REDs (2018, updated 2023) - risks of chronic under-fuelling (REDs). doi:10.1136/bjsports-2018-099193 (opens in a new tab)doi:10.1136/bjsports-2023-106994 (opens in a new tab)
"From Metabolism to Medals: Contemporary Perspectives and Revisiting Carbohydrate Guidelines for Fueling Endurance Athletes during Exercise", Journal of Nutrition (2026) - elite 100-120+ g/h field reports; supports ~90-120 g/h only if gut-trained. doi:10.1016/j.tjnut.2026.101442 (opens in a new tab)
Burke et al. (2017), Journal of Physiology - low-carb keto adaptation impairs exercise economy in elite race walkers. doi:10.1113/JP273230 (opens in a new tab)PMC5407976 (opens in a new tab)
ISSN position stand: protein and exercise (2017) - 1.4-2.0 g/kg/day for active people. doi:10.1186/s12970-017-0177-8 (opens in a new tab)
Jeukendrup, "Training the Gut for Athletes", Sports Medicine (2017). doi:10.1007/s40279-017-0690-6 (opens in a new tab)PMC5371619 (opens in a new tab)
Impey et al., "Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis", Sports Medicine (2018). doi:10.1007/s40279-018-0867-7 (opens in a new tab)PMC5889771 (opens in a new tab)
Maughan et al., IOC consensus statement: dietary supplements and the high-performance athlete, British Journal of Sports Medicine (2018) - grading + protocols for caffeine, nitrate, bicarbonate, beta-alanine, creatine. doi:10.1136/bjsports-2018-099027 (opens in a new tab)PMC5867441 (opens in a new tab)
"Carbohydrates and Endurance Exercise: A Narrative Review of a Food First Approach" (2023) - pre-race meal composition and timing. PMC10054587 (opens in a new tab)
"Nutritional strategies to promote postexercise recovery" (2010) - post-exercise carbs + protein for glycogen resynthesis. PubMed 21116024 (opens in a new tab)
"Maltodextrin-Based Carbohydrate Oral Rinsing and Exercise Performance: Systematic Review and Meta-Analysis", Sports Medicine (2022) - mouth rinse: small benefit in ~30-75 min exercise. PMC9325805 (opens in a new tab)

field & practitioner sources (practice, not research)

Precision Fuel & Hydration sweat-test database + Andy Blow, "How to estimate how much sodium you lose in your sweat" (medically reviewed) - ~950 mg/L average, roughly ten-fold spread, 30,000+ tests. precisionhydration.com (opens in a new tab)
UP&RUN (india), "Know Your Sweat" - indian sweat-test calculator; ~920 mg/L mean, 60-70% in-session replacement. upandrun.in (opens in a new tab)
Davey Nutrition (sports nutritionist), "HYROX Fuelling Overview" - hybrid protocol: 6-8 g/kg load 24-48 h, last meal 3-4 h out, 30-60 g top-up. daveynutrition.com (opens in a new tab)
James Witts, "How to fuel the Ironman", 220 Triathlon - coach Fran Bungay: feed every 15-20 min on the bike with real food to beat flavour fatigue. 220triathlon.com (opens in a new tab)
Sean McAlister, Olympics.com, "How to fuel, rest and recover like Eliud Kipchoge" - elite practice: ~10 h daily sleep; coach Addy Ruiter on the 10-hour rule. olympics.com (opens in a new tab)
Marathon Handbook, "The Runner's Guide to Carb Loading" - practical companion reading. marathonhandbook.com (opens in a new tab)
Runner's World, "What to eat before a 10K", with SiS sports nutritionist Emma Barraclough - 10k practice: carb-rich dinner, familiar breakfast 2-3 h out, ~500 ml fluid pre-start, no fuel during. runnersworld.com (opens in a new tab)
Science in Sport athlete interview, "How Eilish McColgan Fuels for Performance" - elite 10k race-day routine from the european 10k road record holder (SiS-sponsored; brand-published practice). scienceinsport.com (opens in a new tab)

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