Low Carbohydrate Availability Impairs Muscle Growth and High Intensity Performance
A new review by US military nutrition researchers highlights the evidence that restricting carbohydrate intake increases protein oxidation, which can impair muscle protein synthesis and anaerobic performance. Carbohydrates–which come almost exclusively from plant foods such as legumes, grains, fruits and starchy vegetables–have been shown to be the optimal fuel for endurance and strength exercise, and limiting intake can force the body to burn more protein as an alternative fuel source.
The peer-reviewed paper describes how just 24 hours of low carbohydrate intake increases amino acid oxidation and reduces signaling mechanisms involved with muscle growth. Long term restriction (8-12 weeks) leads to alterations in anabolic signaling, protein synthesis, and myogenesis which likely contribute to limited muscular responses to resistance training.
These findings align with previous research showing that carbohydrate-rich diets result in significantly improved outcomes in time trials, one-rep max lifts and body composition measures when compared with low carbohydrate ketogenic diets.
The researchers conclude that carbohydrate restriction increases amino acid oxidation, impairs muscle hypertrophy and anaerobic performance, and that “athletes who need to perform high intensity exercise should avoid nutrition strategies that restrict carbohydrates”.
References:
Margolis, L. M., & Pasiakos, S. M. (2023). Low carbohydrate availability impairs hypertrophy and anaerobic performance. Current opinion in clinical nutrition and metabolic care, 10.1097/MCO.0000000000000934. Advance online publication.
Koerich, A. C. C., Borszcz, F. K., Thives Mello, A., de Lucas, R. D., & Hansen, F. (2022). Effects of the ketogenic diet on performance and body composition in athletes and trained adults: a systematic review and Bayesian multivariate multilevel meta-analysis and meta-regression. Critical reviews in food science and nutrition, 1–26. Advance online publication.