HMB (β-Hydroxy-β-Methylbutyrate) is a metabolite of the amino acid Leucine and is one of the most effective natural anabolic compounds – both preventing the breakdown of muscle fibers while increasing protein synthesis. As a result, HMB supplementation may increase muscle recovery after intense exercise, boost muscle growth, and even enhance endurance while working out. While the human body does have a limited ability to convert Leucine to HMB, it’s thought that the only way to significantly increase blood HMB levels is through dietary supplementation.