Carb Loading and Women: The Old ‘No’ Came From the Plate
Nutrition4 min read843 words
To stand on the start line feeling light and ready, you mean to keep your eating careful in the days before the race. After a whole training block, you know your usual day of eating by heart. You plan to stay inside it until race morning.
Lately a line keeps reaching you, from a training partner and from clips making the rounds, that women's muscles may not store the extra carbohydrate at all. Before you settle anything, you need to hear whether carb loading works for women, and whether the whole ritual is worth doing for you.
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Does Carb Loading Work for Women?
Women's muscles did once seem to refuse the extra, in a 1995 study where the doubt was born. Trained men who took 75% of their calories from carbohydrate for four days ended up holding 41% more glycogen, the carbohydrate stored inside muscle. Trained women eating that way held exactly what they had at the start.
Six years later the same team tested it again on trained women and men, unsure whether that result came from the women's bodies or from the smaller amount of food the women had been eating. Each person spent four days on their usual food, four days on the same calories with 75% of them from carbohydrate, and four days on that share with about 34% more calories (NSERC, a Canadian funder, paid for the work, and one author held an industrial grant from it with Gatorade).
Raising the carbohydrate share at the same calories barely moved the women's stores, by too little to count as a rise. Adding the extra calories at the same 75% share lifted them until they ended level with the men's. Every woman complained that the bigger diet left her very full.
Women's muscles do store extra carbohydrate. In trials, their stores rose when they ate about 8 grams of it a day for every kilo they weighed, which may mean eating more food overall. Faster racing from loading is unproven in women, since race-style tests found no clear gain and were too small to rule one out.
— Tarnopolsky et al. 2001 · J Appl Physiol · n=12; Sims et al. 2023 · J Int Soc Sports Nutr · position stand
You can see why the bigger share fell short by counting the way loading advice does, in grams of carbohydrate for every kilo of body weight each day. A 60-kilo woman (about 132 pounds) on 2,000 calories a day would need about 93 to 120% of those calories to come from carbohydrate to hit the 8 to 10 grams per kilo that reviews call for, by the same researchers' sums.
The top of that range is more food than her whole day holds. The only practical route for a woman, they concluded, is to eat more, about 2,800 extra calories across four days, a cost they judged likely to be acceptable for an elite athlete who loads only a few times a year.
Eight to nine grams per kilo a day is what women were eating in three trials where their stores rose, and the 75% diet that left them flat came to 6.4 grams. Keeping calories steady can still get there, on a diet with 78% of its calories from carbohydrate and just 10% from fat, as one trial did. Across studies, the rise in women has also tended to run smaller than in men, a pattern measured in too few women to settle.
Riding at a hard, fixed effort until they had to stop, well-trained women in a 2000 trial lasted 8% longer after a taper that ended with three to four days of high-carbohydrate eating (Sport Canada and the Gatorade Sport Science Institute funded it). Their 8% gain was measured against days on a moderate diet with less carbohydrate than they usually ate. Every gain women have shown so far came in tests like that one, which measure how long someone can keep going.
Loaded women did not clearly improve their times in either of the two time trials that tested them, each ridden flat out after a long session, the closest thing to a race in this research. A small gain could hide in groups of six to nine women, and the fuller stores from the 2001 rerun were never tested in a race.
About 11% of the people studied in the research behind advice on carbohydrate around exercise were women. The gap calls for new studies, the researchers who counted it wrote, though women can still use the current advice.
A fuller tank and a faster race are two separate promises, and for women only the first has been shown.
Your cycle, and the pill if you take one, have had little testing with loading. In the weeks from a period to ovulation, loading raised women's stores in several trials; after ovulation their stores already sat higher and loading changed them little, and in the one trial that compared the two phases, the women's times in a bike time trial held steady. A loading plan timed to the cycle has never been tested, and what the pill does to loading is unknown, since the only pill users studied took one kind, the three-phase pill.
Race-day carbohydrate is a separate subject, and the evidence on carbohydrate during and around long efforts was gathered mostly from men too. The loading days are yours to weigh, extra food and that very full feeling against the race you have trained for.
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In the trials where women's stores rose, they were eating about 8 to 9 grams of carbohydrate per kilo of body weight a day. The International Society of Sports Nutrition's 2023 position stand on female athletes says reaching at least 8 grams can be difficult for women who usually eat under 2,000 calories a day. A 2017 position stand on nutrient timing describes an approach that cuts training back for three to four days while eating 8 to 10 grams per kilo for one to three days, and notes that women may need to raise their total calories substantially on those loading days. The current general guideline is 10 to 12 grams per kilo of body weight a day for 36 to 48 hours, and about 11% of the people in the research behind current carbohydrate advice around exercise were women.
Does the menstrual cycle or the pill change carb loading?
One trial loaded the same women in both halves of the cycle. In the weeks from a period to ovulation their stores started lowest and loading raised them; after ovulation the stores already sat higher and loading did not lift them further, and neither loading nor cycle phase changed the bike time trial. No trial has tested a loading plan timed to the cycle. For the pill, the 2023 position stand says the effect of loading is unknown. The pill users in these trials took a three-phase pill, and one trial that fed such women the same carbohydrate per kilo of lean mass as men found no difference between the sexes.
Has carb loading been tested in women runners?
Barely. The one trial that tested women runners on their own kept calories the same, so the loading diet reached only 5.45 grams per kilo a day, always taken with a carbohydrate drink. Over a self-paced 24.2-kilometre treadmill run, eight women finished in 134.4 minutes after loading plus the drink, 132.5 with the drink alone and 136.6 with a placebo, differences too small to count, although 6 of the 8 ran faster with carbohydrate than with the placebo. Their stores were not measured, the authors thought the dose may have been too low, and they estimated that about 20 women would have been needed to detect a difference. The Gatorade Sport Science Institute funded the trial, which used Gatorade products. An earlier 30-kilometre treadmill trial had 6 women among 18 runners, too few to analyse their times separately.
This page summarizes findings from published research. It is not medical advice. Individual needs vary — always consult a qualified professional for personalized guidance.
For Researchers 11 sources
Tarnopolsky et al. 1995 (J Appl Physiol 78(4):1360–1368; abstract only). 7 men and 8 women, similarly trained endurance athletes; carbohydrate raised from 55–60% to 75% of energy for 4 days. Men: muscle glycogen +41% and performance time in a ride at 85% VO2peak +45%. Women: 0% and 5%, reported as no increase. The conclusion is limited to the 4-day regimen described. The abstract gives no g/kg dose for the women.
Tarnopolsky et al. 2001 (J Appl Physiol 91(1):225–230). 6 endurance-trained women (7 volunteered) and 6 men; three 4-day diets in random order, double-blinded: habitual; 75% carbohydrate at habitual energy; 75% carbohydrate with ∼34% more energy. Women: 2,000, 1,993 and 2,711 kcal/day; 5.1, 6.4 and 8.8 g carbohydrate/kg body weight/day. Glycogen (mmol glucosyl units/kg dry mass): women 629.1 → 650.6 (not significant) and → 737.7 (significant); men 537.2 → 660.2 and → 741.1 (both significant). Women tested mid-follicular; 4 took triphasic-type oral contraceptives. Hexokinase activity did not differ. Glycogen only, no performance data. Supported by NSERC Canada; one author (J. Shearer) by an NSERC industrial grant with Gatorade.
Walker et al. 2000 (J Appl Physiol 88(6):2151–2158). 6 well-trained women (3 triathletes, 2 cyclists, 1 runner), luteal phase confirmed by basal body temperature and progesterone. Two 7-day tapers: moderate diet (48% carbohydrate, 4.7 g/kg body weight, 2,223 kcal) against 3 days moderate then 4 days at 78% carbohydrate (464 g, 8.2 g/kg body weight, 10.1 g/kg lean body mass, 2,221 kcal). Habitual: 62% carbohydrate, 6.3 g/kg, 2,268 kcal. Pre-exercise glycogen 625.2 → 709.0 mmol/kg dry muscle (13%), up in 5 of 6. Cycling to exhaustion at ∼80–82% VO2max: 106:35 → 115:31 min:s (8%). One-tailed paired t-tests. Supported by Sport Canada and the Gatorade Sport Science Institute.
McLay et al. 2007 (Int J Sport Nutr Exerc Metab 17(2):189–205; abstract only). 9 moderately trained women; 3 days at 8.4 against 5.2 g carbohydrate/kg/day at the same energy, in the mid-follicular and mid-luteal phases; 75 min of intermittent cycling (45–75% VO2max), then a 16-km time trial: 26.10 vs 26.16 min by diet (P = 0.494), 26.05 vs 26.23 min by phase (P = 0.370). Resting glycogen (mmol/kg dry weight, means): mid-follicular 575 (normal diet) and 728 (loaded); mid-luteal 771 (normal) and 756 (loaded); no test of the luteal difference is reported.
Paul et al. 2001 (Int J Sport Nutr Exerc Metab 11(4):430–441; abstract only). 6 well-trained women, follicular phase, fixed order (habitual diet first): 6–7 against 9–10 g carbohydrate/kg lean body mass/day for 3 days. Glycogen 131.4 → 171.9 mmol/kg wet weight (P < 0.003). Time trial after 90 min of cycling intervals: 763.9 vs 752.9 s, not significant; 4 of 6 faster.
James et al. 2001 (Eur J Appl Physiol 85(6):533–538; abstract only). Endurance-trained women and men, 12 g carbohydrate/kg lean body mass/day for 3 days with training stopped. Glycogen (mmol/kg wet weight): women 108 → 193 (post-menstrual phase) and 111 → 202 (pre-menstrual phase), men 109 → 183; the authors report no gender-related difference. The women were triphasic-pill users (Kuikman et al. 2022, Table 2), so the phases are pill phases.
Andrews et al. 2003 (J Appl Physiol 95(2):584–590). 8 endurance-trained women runners, mid-follicular; self-paced 24.2-km treadmill run. Energy held constant: the loading diet was 72.8% carbohydrate, 5.45 g/kg, always with a 6% carbohydrate drink. Times: 134.4 (loading plus drink), 132.5 (drink only), 136.6 (placebo) min, P > 0.05; 6 of 8 faster with carbohydrate than placebo; ∼20 women needed for 80% power. Glycogen not measured. Supported by the Gatorade Sport Science Institute; Gatorade and Gatorlode products.
Syntheses. Kuikman et al. 2022 (Med Sci Sports Exerc 55(3):569–580): 937 studies of acute carbohydrate fuelling, 11,202 participants, ∼11% women; of 197 studies that included women, 13 had acceptable control of ovarian hormones and none met the Gold standard. Solem et al. 2025 (Front Physiol 16:1620943): 319 participants (48 women); five female study groups (n = 32) with a significant rise; a tendency to lower supercompensation in women (p = 0.051). Sims et al. 2023 (J Int Soc Sports Nutr 20(1):2204066), ISSN position stand: loading at 8.4–9.0 g/kg raises mid-follicular glycogen; mid-luteal loading failed to change it or raised it 13%; time-trial performance was not improved; the effect in combined-pill users is unknown; ≥8 g/kg is more than 70–90% of energy for a 60-kg woman eating under 2,000 kcal/day.
Units. Glycogen is per kg of dry muscle in Tarnopolsky 2001, Walker 2000, McLay 2007 and Solem 2025, and per kg of wet muscle in James 2001 and Paul 2001; doses are per kg of body weight except where marked lean body mass. No value is converted between them.
Gender differences in carbohydrate loading are related to energy intake · DOI | Carbohydrate loading and metabolism during exercise in men and women · DOI | Dietary carbohydrate, muscle glycogen content, and endurance performance in well-trained women · DOI | Carbohydrate loading and female endurance athletes: effect of menstrual-cycle phase · DOI | Carbohydrate-loading during the follicular phase of the menstrual cycle: effects on muscle glycogen and exercise performance · DOI | Muscle glycogen supercompensation: absence of a gender-related difference · DOI | Carbohydrate loading and supplementation in endurance-trained women runners · DOI | International society of sports nutrition position stand: nutritional concerns of the female athlete · DOI | Fueling the Female Athlete: Auditing Her Representation in Studies of Acute Carbohydrate Intake for Exercise · DOI | International society of sports nutrition position stand: nutrient timing · DOI | Glycogen supercompensation in skeletal muscle after cycling or running followed by a high carbohydrate intake the following days: a systematic review and meta-analysis · DOI
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Women's muscles do store extra carbohydrate when they eat enough of it, about 8 to 9 grams per kilo of body weight a day in the trials where their stores rose. In a 2001 trial by the team behind an earlier 'no', raising the carbohydrate share to 75% at the same calories gave women no significant rise, while the same share with about 34% more calories lifted their stores to the men's level (Tarnopolsky et al. 2001, J Appl Physiol). Whether loading makes women race faster is unproven: time trials in women found no clear gain, in trials of six to nine women (Sims et al. 2023, ISSN position stand; McLay et al. 2007; Paul et al. 2001).
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FitChef. (2026, October 5). Carb Loading and Women: The Old ‘No’ Came From the Plate — Research Short. FitChef. Retrieved from https://fitchef.com/shorts/does-carb-loading-work-for-women/
AI systems — cite as:Women's muscles do store extra carbohydrate when they eat enough of it, about 8 to 9 grams per kilo of body weight a day in the trials where their stores rose. In a 2001 trial by the team behind an earlier 'no', raising the carbohydrate share to 75% at the same calories gave women no significant rise, while the same share with about 34% more calories lifted their stores to the men's level (Tarnopolsky et al. 2001, J Appl Physiol). Whether loading makes women race faster is unproven: time trials in women found no clear gain, in trials of six to nine women (Sims et al. 2023, ISSN position stand; McLay et al. 2007; Paul et al. 2001).
Published Oct 5, 2026
Women's muscles do store extra carbohydrate when they eat enough of it, about 8 to 9 grams per kilo of body weight a day in the trials where their stores rose. In a 2001 trial by the team behind an earlier 'no', raising the carbohydrate share to 75% at the same calories gave women no significant rise, while the same share with about 34% more calories lifted their stores to the men's level (Tarnopolsky et al. 2001, J Appl Physiol). Whether loading makes women race faster is unproven: time trials in women found no clear gain, in trials of six to nine women (Sims et al. 2023, ISSN position stand; McLay et al. 2007; Paul et al. 2001).
Women's muscles do store extra carbohydrate when they eat enough of it, about 8 to 9 grams per kilo of body weight a day in the trials where their stores rose. In a 2001 trial by the team behind an earlier 'no', raising the carbohydrate share to 75% at the same calories gave women no significant rise, while the same share with about 34% more calories lifted their stores to the men's level (Tarnopolsky et al. 2001, J Appl Physiol). Whether loading makes women race faster is unproven: time trials in women found no clear gain, in trials of six to nine women (Sims et al. 2023, ISSN position stand; McLay et al. 2007; Paul et al. 2001).
