HMB is a metabolite of the amino acid leucine, which promotes muscle hypertrophy and decreases body fat by stimulating a key anabolic regulator known as the mTor pathway. HMB also helps to downregulate the production of myostatin, a protein that blocks the anabolic pathway and thus, prevents muscle growth.
According to Jay Hoffman, from the University of Central Florida, Orlando, HMB may also help to prevent the inflammatory response and immune suppression which often accompanies overtraining. This can lead to infections, especially of the upper respiratory tract, decreased performance and muscle breakdown (catabolism).
By supplementing three grams of HMB per day for twenty three days in over trained soldiers, researchers were able to show a significant reduction in catabolism, immune suppression and inflammation compared to group of soldiers who received a placebo or fake HMB supplement.
HMB is an effective supplement for athletes performing intense exercise, and compliments a number of supplements which have also proven to be effective in promoting muscle mass and increasing strength such as creatine. (Nutrition Research, 36: 553-563, 2016)