HMB (beta-hydroxy-beta-methylbutyrate) is a by product of the branched chain amino acid Leucine in the process of metabolism. HMB stimulates essentially the same pathways as insulin. HMB sends signals that tell the body to decrease breakdown of skeletal muscle tissue. The end result expected to be improved muscle growth response to weight training.
Studies show that 3 grams daily of HMB is necessary to get its anti-catabolic activity on skeletal muscle. The 3 grams should be taken in one gram divided doses throughout the day for best effect.
However, it should be noted that HMB’s effect beyond placebo is only about two weeks. By the time 4-6 weeks comes around the HMB using group and placebo control group demonstrated the same muscle gains. A 2009 study in the Journal of Strength and Conditioning Research showed no increase in power output or strength gains in trained athletes.
Current data seems to indicate that HMB is best used in the elderly and those who are not able to exercise. Clinical muscle wasting conditions like AIDS, cancer, bed rest, and times of heavy caloric deficit would likely have a positive effect from HMB supplementation. It is our opinion that the general population and athletes alike would be better off sticking with Leucine and the other BCAAs, not only for their anabolic benefits but also their body composition support..