Among anti-atrophic therapies, amino acid supplementation, particularly with leucine, has received a lot of attention. Atrophic conditions include muscle disuse, sarcopenia and cancer. The characterization of the mechanisms underlying skeletal muscle atrophy under different conditions has been a constant focus of research. Supplementation has been shown to have remarkable effects on muscle remodeling through protein turnover modulation. This may then impact physiological parameters related to muscle function and even improve quality of life. In light of this, leucine supplementation could be a useful therapy for mitigating the atrophic effects of catabolic conditions.