Why insulin alone doesn't build muscle
Insulin fails to enhance mTOR phosphorylation, mitochondrial protein synthesis, and ATP production in human skeletal muscle without amino acid replacement.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Insulin is like a 'build muscle' signal, but it needs amino acids (from protein) to work. This study gave people insulin without letting them eat protein and saw what happened.
Systematic Reviews & Meta-Analyses
Max 100Randomized Controlled Trials
Max 90Cohort Studies
Max 72Case-Control Studies
Max 58Cross-Sectional Studies
Max 44Case Reports & Case Series
Max 30Expert Opinion & Narrative Reviews
Max 554 / 90
Evidence Score
Participants are randomly assigned to treatment or control groups, minimizing bias. Considered the gold standard for testing whether an intervention causes an effect.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Insulin is like a 'build muscle' signal, but it needs amino acids (from protein) to work. This study gave people insulin without letting them eat protein and saw what happened.
Systematic Reviews & Meta-Analyses
Max 100Randomized Controlled Trials
Max 90Cohort Studies
Max 72Case-Control Studies
Max 58Cross-Sectional Studies
Max 44Case Reports & Case Series
Max 30Expert Opinion & Narrative Reviews
Max 554 / 90
Evidence Score
Participants are randomly assigned to treatment or control groups, minimizing bias. Considered the gold standard for testing whether an intervention causes an effect.
Publication
Authors
Barazzoni R, Short KR, Asmann Y, Coenen-Schimke JM, Robinson MM, Nair KS
Related Content
Claims (6)
Leucine, an amino acid, triggers a cellular pathway called mTOR that starts the production of muscle proteins. When carbohydrates are consumed at the same time, the resulting increase in insulin levels boosts this process.
In healthy young adults, insulin alone cannot trigger key cellular processes for building proteins in muscle unless amino acids are also present, even though insulin still activates its initial signaling step.
In healthy young adults, high insulin levels alone, without additional amino acids, do not improve the mitochondria's ability to produce energy, even though genes related to mitochondria become more active at the RNA level.
When insulin is infused into healthy young adults without providing amino acids, the levels of key amino acids in the blood drop by 40–50% within 7 hours, and this is accompanied by a decrease in muscle protein synthesis and no activation of the mTOR signaling pathway.
In healthy young adults, prolonged high insulin levels without accompanying amino acids reduce the rate of muscle protein synthesis by 20-30% during the final five hours of insulin infusion, even though genes related to mitochondrial function are more active, showing that amino acids are required for insulin to promote muscle protein synthesis.