Does extra leucine make your muscles grow bigger?
Leucine Supplementation Has No Further Effect on Training-induced Muscle Adaptations
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Leucine supplementation had zero effect on muscle growth or strength despite its known role in activating mTORC1 — the 'muscle growth switch'.
Acute studies show leucine spikes MPS after a meal, so scientists expected long-term use to compound gains. This study proves the body adapts — and extra leucine is ignored once protein is sufficient.
Practical Takeaways
Stop buying leucine powder. Focus on hitting 1.6–1.8g protein per kg of body weight daily from whole foods like chicken, eggs, dairy, and legumes.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Leucine supplementation had zero effect on muscle growth or strength despite its known role in activating mTORC1 — the 'muscle growth switch'.
Acute studies show leucine spikes MPS after a meal, so scientists expected long-term use to compound gains. This study proves the body adapts — and extra leucine is ignored once protein is sufficient.
Practical Takeaways
Stop buying leucine powder. Focus on hitting 1.6–1.8g protein per kg of body weight daily from whole foods like chicken, eggs, dairy, and legumes.
Publication
Journal
Medicine & Science in Sports & Exercise
Year
2020
Authors
Isabel Thomazi de Andrade, B. Gualano, Victoria Hevia-Larraín, Juarez Neves Junior, M. Cajueiro, F. Jardim, R. L. Gomes, G. Artioli, Stuart M Phillips, P. Campos-Ferraz, H. Roschel
Related Content
Claims (6)
If you're a young man who lifts weights regularly, eating 1.8 grams of protein per kilogram of your body weight every day is enough to build as much muscle as you can from training—adding extra leucine powder won't help you get any bigger or stronger.
If you're a young guy who lifts weights and you take 10 grams of leucine powder split into two doses a day, it won't make you eat more or less protein or leucine from your regular food.
If you're a young man who already lifts weights and eats enough protein, doing strength training twice a week for 12 weeks will make you stronger and build more muscle — and taking leucine supplements won't make any extra difference compared to taking a sugar pill.
Taking leucine supplements won’t help young athletes build more muscle, get stronger, or recover faster—even though leucine is known to trigger a muscle-growth signal in the body.
If you're a young guy who lifts weights and already eats enough protein, taking extra leucine pills for 12 weeks won't make you stronger or build more muscle in your thighs than just lifting weights by itself.