Nutrition7 min read
Can you build muscle on keto?
A ketogenic (keto) diet cuts carbohydrate to roughly 50 g a day or less, so the body runs mainly on fat and ketones. It can help some people lose weight. For building muscle and training hard in the gym, the research in trained lifters points the other way: keto tends to make muscle gain slower, and it can make high-volume sessions feel harder.
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The short answer
You can keep muscle on keto, but building it is harder. In controlled trials of trained lifters, people on keto gained less lean mass than people eating the same protein and calories with more carbohydrate, and some lost lean mass (Vargas et al., 2018; Vargas-Molina et al., 2020). Maximal strength often holds, but high-volume training can suffer. If muscle growth is your main goal, keto is not the best choice.
- Short, heavy, low-rep strength can be maintained on keto (Greene et al., 2018).
- Carbohydrate matters most for longer, high-volume sessions, roughly 10 or more sets per muscle (Henselmans et al., 2022).
Does keto stop you building muscle?
In CrossFit trainees, leg lean mass fell over 12 weeks on keto (Kephart et al., 2018). In another trial, lean mass dropped while men lifted on keto and only came back once carbohydrate was added again. Part of that change is water and stored carbohydrate in muscle, not just muscle tissue (Wilson et al., 2020).
How keto affects gym and weight-lifting performance
Your muscles fuel hard sets of 6–20 reps largely from stored carbohydrate (glycogen). Keto lowers those stores, so long sessions with many sets close to failure are the most likely to suffer (Escobar, VanDusseldorp and Kerksick, 2016).
Strength on heavy, low-rep lifts is a different story. Powerlifters and weightlifters on keto kept their competition lifts while losing bodyweight (Greene et al., 2018). So keto is more likely to harm bodybuilding-style volume work than a one-rep max.
Is keto bad for bodybuilding and muscle growth?
- Expect higher-rep and high-volume sessions to feel harder, especially in the first few weeks.
- Fewer reps per set at the same weight means less training stimulus over time.
- Keto is usually also lower in calories, and a deficit makes muscle gain harder on any diet.
Best diet for building muscle instead of keto
For muscle growth, the joint sports-nutrition position statement recommends enough energy, enough protein and carbohydrate matched to how much you train (Thomas, Erdman and Burke, 2016). Find your figures with the muscle gain protein calculator and the carbohydrate calculator.
Thinking of taking high-dose vitamins to recover faster? Read about antioxidants and muscle growth first.
People also ask
Is keto bad for muscle growth?
For most lifters it is worse than a diet with more carbohydrate. Trials found keto groups gained less lean mass with the same training and protein.
Does keto burn muscle?
Keto does not burn muscle by itself, but some trials saw lean mass fall during keto. Part of that is lost water and stored carbohydrate.
Can you lift weights on keto?
Yes. Heavy, low-rep strength often holds up. Long, high-volume sessions are more likely to feel harder.
Is keto good for bodybuilding?
Not for gaining size. Some people use it to lose fat, but it tends to slow muscle gain compared with eating more carbohydrate.
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Scientific References & Evidence
- Escobar, K.A., VanDusseldorp, T.A. and Kerksick, C.M. (2016) 'Carbohydrate intake and resistance-based exercise: are current recommendations reflective of actual need?', British Journal of Nutrition, 116(12), pp. 2053-2065. doi: 10.1017/S0007114516003949. Available at: https://doi.org/10.1017/S0007114516003949
- Greene, D.A., Varley, B.J., Hartwig, T.B., Chapman, P. and Rigney, M. (2018) 'A low-carbohydrate ketogenic diet reduces body mass without compromising performance in powerlifting and Olympic weightlifting athletes', Journal of Strength and Conditioning Research, 32(12), pp. 3373-3382. doi: 10.1519/JSC.0000000000002904. Available at: https://doi.org/10.1519/JSC.0000000000002904
- Henselmans, M., Bjørnsen, T., Hedderman, R. and Vårvik, F.T. (2022) 'The effect of carbohydrate intake on strength and resistance training performance: a systematic review', Nutrients, 14(4), p. 856. doi: 10.3390/nu14040856. Available at: https://doi.org/10.3390/nu14040856
- Kephart, W.C., Pledge, C.D., Roberson, P.A., Mumford, P.W., Romero, M.A., Mobley, C.B., Martin, J.S., Young, K.C., Lowery, R.P., Wilson, J.M., Huggins, K.W. and Roberts, M.D. (2018) 'The three-month effects of a ketogenic diet on body composition, blood parameters, and performance metrics in CrossFit trainees: a pilot study', Sports, 6(1), p. 1. doi: 10.3390/sports6010001. Available at: https://doi.org/10.3390/sports6010001
- Thomas, D.T., Erdman, K.A. and Burke, L.M. (2016) 'Nutrition and athletic performance', Medicine & Science in Sports & Exercise, 48(3), pp. 543-568. doi: 10.1249/MSS.0000000000000852. Available at: https://doi.org/10.1249/MSS.0000000000000852
- Vargas, S., Romance, R., Petro, J.L., Bonilla, D.A., Galancho, I., Espinar, S., Kreider, R.B. and Benítez-Porres, J. (2018) 'Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial', Journal of the International Society of Sports Nutrition, 15(1), p. 31. doi: 10.1186/s12970-018-0236-9. Available at: https://doi.org/10.1186/s12970-018-0236-9
- Vargas-Molina, S., Petro, J.L., Romance, R., Kreider, R.B., Schoenfeld, B.J., Bonilla, D.A. and Benítez-Porres, J. (2020) 'Effects of a ketogenic diet on body composition and strength in trained women', Journal of the International Society of Sports Nutrition, 17(1), p. 19. doi: 10.1186/s12970-020-00348-7. Available at: https://doi.org/10.1186/s12970-020-00348-7
- Wilson, J.M., Lowery, R.P., Roberts, M.D., Sharp, M.H., Joy, J.M., Shields, K.A., Partl, J.M., Volek, J.S. and D'Agostino, D.P. (2020) 'Effects of ketogenic dieting on body composition, strength, power, and hormonal profiles in resistance training men', Journal of Strength and Conditioning Research, 34(12), pp. 3463-3474. doi: 10.1519/JSC.0000000000001935. Available at: https://doi.org/10.1519/JSC.0000000000001935
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Educational information for adults aged 18 and over. It does not diagnose, treat or manage any medical condition. If you have a health condition, or symptoms that worry you, speak to your doctor or a health professional.