Nutrition for CrossFit

CrossFit is a multimodal training methodology that combines high-intensity functional movements, strength, power, and endurance. (1) Despite the demanding nature of daily workouts (WODs), many recreational and competitive athletes do not adequately fuel for training. Nutritional habits are often shaped by anecdote or popular diet trends rather than research evidence. Although research on nutrition specifically for CrossFit is still developing, recent research provides key recommendations that can be applied to CrossFit athletes.

Energy demands of CrossFit

A single CrossFit WOD often includes a combination of strength, gymnastics, and endurance. The intermittent, high-intensity nature of these workouts places substantial demands on the body's energy systems, leading to rapid use of muscle glycogen (carbohydrate stores). Research shows that even 10–15 minutes of high-intensity exercise can reduce muscle glycogen by 40–60%, comparable to 60–90 minutes of moderate-intensity endurance training. (2)

Carbohydrates are the primary fuel source for CrossFit WODs. During a WOD, the body can rely heavily on carbohydrate stores to sustain repeated bursts of power, speed, and anaerobic effort, far more so than fats or proteins. When carbohydrate availability is low, performance declines, fatigue sets in earlier, and recovery can be impaired. (3) For this reason, CrossFit athletes, including recreational CrossFitters, require moderate-to-high daily carbohydrate intake to support training quality, maintain performance, and to recover effectively across the week.

What do CrossFitters eat?

Recent research shows a clear pattern: most CrossFit athletes eat enough protein but not enough carbohydrates. (3) Studies have found that athletes following higher-carbohydrate diets perform better in training and competition. On the other hand, low-carbohydrate or ketogenic (low carb, high fat) diets show limited benefits and may even hinder performance.

What should CrossFitters eat?

Carbohydrates: daily carbohydrate intake should match training volume:

• Moderate training load (3–4 sessions/week): 5–7 g/kg of bodyweight/day. For example, for someone with a bodyweight of 60kg, this means 300-420g of carbs per day.

• High training load (>5 sessions/week) or competition preparation: 8–10 g/kg of bodyweight/day

While consuming carbohydrates pre-WOD (or during long sessions/multiple WODs) can be helpful, overall daily carbohydrate availability has the strongest effect on performance and recovery. (4)

Protein: protein intake of 1.6–2.2 g/kg of bodyweight/day supports muscle repair, hypertrophy, and adaptation. Intakes above this range do not show additional performance benefits for most athletes.

Supplements

Two supplements have consistent, evidence-based benefits for high-intensity functional training, such as CrossFit:

Creatine: creatine is one of the most researched sports supplements. It increases muscle phosphocreatine stores, improving ATP re-synthesis and enhancing performance in short, intense, repeated efforts.

• Benefits: strength, power, repeated high-intensity efforts (5)

• Recommended dose: 3-5g/day

Caffeine: there is strong evidence that caffeine improves performance by increasing alertness, reducing fatigue, enhancing neural drive, and lowering perceived exertion. (6)

• Benefits: sustained power, focus, reduced rate of perceived exertion, improved performance in both strength and conditioning WODs

• Recommended dose: 3–6 mg/kg, ~60 minutes pre-exercise

• Caution: avoid intake later in the day as caffeine may disrupt sleep

Branched-chain amino acids (BCAAs) and many popular pre-workout ingredients lack robust evidence for improving performance in well-fuelled CrossFit athletes.

Summary

• CrossFit performance depends on carbohydrates: carbohydrate stores fuel the repeated bursts of power, speed, and anaerobic effort typical of WODs. Insufficient carbohydrate availability compromises performance, increases fatigue, and impedes recovery.

• Aim to meet daily carbohydrate needs based on training volume:

  • Moderate load (3–4 sessions/week): 5–7 g/kg/day

  • High load (>5 sessions/week) or competition blocks: 8–10 g/kg/day

• Ensure protein intake remains within 1.6–2.2 g/kg/day to support repair and adaptation.

• Use only evidence-backed supplements:

  • Creatine (3-5 g/day) - supports strength, power, repeated efforts

  • Caffeine (3-6 mg/kg pre-WOD) - enhances alertness, reduces fatigue, boosts performance

• Prioritise carbohydrate availability first - supplements should supplement, not substitute, a good diet for performance and overall health.

References:

1. CrossFit. www.crossfit.com

2. MacInnis, M. J., & Gibala, M. J. (2017). Physiological adaptations to interval training and the role of exercise intensity. Exercise and Sport Sciences Reviews, 45(2), 58–65.

3. Martinho, D., Teixeira, F. J., Gouveia, É. R., Lima, R. F., & Correia, J. M. (2025). Nutritional intake of CrossFit athletes: A systematic review and meta-analysis. International Journal of Sport Nutrition and Exercise Metabolism, 31(2), 187–196.

4. Ribeiro, A. S., Schoenfeld, B. J., Pina, F. L. C., & Nascimento, M. A. (2021). Nutritional strategies to optimize performance and recovery in CrossFit: A narrative review. Nutrition, 82, 111051.

5. Kreider, R.B.; Kalman, D.S.; Antonio, J.; Ziegenfuss, T.N.; Wildman, R.; Collins, R.; Candow, D.G.; Kleiner, S.M.; Almada, A.L.; Lopez, H.L. International society of sports nutrition position stand: Safety and efficacy of creatine supplementation in exercise, sport, and medicine. J. Int. Soc. Sports Nutr. 2017, 14, 18.

6. Guest, N.S., VanDusseldorp, T.A., Nelson, M.T. et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr 18, 1 (2021).