Key benefits Metabolite of the BCAA leucine Protein supports growth & maintenance of muscle mass¹ 1.5g HMB per serving Convenient tablets Product overview HMB (Beta-Hydroxy Beta-Methylbutyrate) is a substance naturally formed within the body when breaking down leucine. This branched-chain amino acid is one of the essential building blocks of protein, which promotes lean muscle growth & maintenance¹. A popular supplement in the weightlifting community, HMB is a great choice when upping the intensity of your workouts. With 1.5g per serving, these convenient capsules are a great addition to your fitness regime.