HMB (β-hydroxy β-methylbutyrate) is a metabolite of the essential amino acid leucine and is synthesized in the human body. It plays a part in protein synthesis. Research has shown that HMB may have an effect on increasing muscle weight and strength. It's act in enhance protein synthesis via the mTOR pathway and depression of protein degradation. Three grams of Calcium beta-hydroxy-beta-methylbutyrate per day may help muscles combat protein breakdown, assist in muscle repair and support increased endurance. Studies suggest its benefits may be greater for the untrained. Also, well-controlled scientific studies have found increases in muscle mass and decreases in body fat in 70 year old men.