Found in grapefruit, cauliflower, red meat, catfish, and other foods, HMB is a breakdown product of the amino acid leucine. Your body produces it naturally from proteins containing leucine. Since its introduction in 1995, the supplement form of HMB has received a lot of press in some fitness magazines for its presumed fat-burning and muscle-building benefits.
Scientists believe HMB prevents muscle breakdown and aids in fat metabolism. Many animal studies have been conducted on HMB, and most have shown that supplementation does two things: It increases lean tissue, and it enhances the immune system. These findings have prompted the use of HMB as an additive in animal feed.
There have been a few studies published in scientific journals on the effects of HMB supplementation in humans. At the University of Iowa, researchers conducted two related studies on HMB. In the first, forty-one men were given 1.5 or 3 grams of HMB, or a placebo, daily while participating in a strength-training program 3 days a week. By the end of 3 weeks, the HMB-takers had gained 63 percent more strength than the others. Plus, muscle breakdown during exercise was minimized among the HMB-supplemented group.
In the second study, twenty-eight volunteers took either 3 grams of HMB or a placebo, and strength-trained 6 days a week for 7 weeks. By the end of the study period, the HMB-takers had lost twice as much body fat as those taking the placebo.
In another study, female athletes who took 3 grams of HMB daily boosted their strength by 7 percent, compared with a placebo-supplemented group.
HMB may increase endurance, too. In one experiment, cyclists in-creased their performance and training intensities dramatically while supplementing with HMB for 2 weeks.
Based on this collection of studies, HMB appears to increase muscle mass and strength, prevent muscle breakdown, support fat loss, and possibly boost stamina. The research certainly gives high marks to HMB, and I think you'll see a lot more studies on HMB in the future.
In the area of AIDS research, a growing number of studies show that malnourished HIV-infected patients may develop the disease more quickly, primarily because of muscle-wasting (cachexia). To help prevent this, some researchers are experimenting with HMB combined with other amino acids. Their goal: to see whether the mixture will slow down muscle-wasting. The mixture is believed to supply immune cells with the amino acids they need so that muscle stores won't be depleted, and to retard muscle breakdown with HMB supplementation. The approach makes sense in theory, but results are not yet conclusive.
How to Take It: HMB is possibly worth a try, especially if you're a serious, hard-training bodybuilder or weight lifter. What kind of results can you expect? The world's leading authority on HMB, Dr. Steve Nissen, was quoted in the magazine Muscle Media as saying that if you strength-train and typically gain 2 pounds of muscle every few weeks, you can possibly gain 3 or 4 pounds of muscle while on HMB.
The recommended dosage is 3 grams daily, taken in divided doses, three times a day. One of those doses should be a few hours before your workout, to give the supplement time to peak in your system and help maximize strength and muscle gains. Additionally, researchers speculate that HMB may work well with carnitine to encourage fat loss.
As for diet, it's best to consume adequate protein while supplementing with HMB and working out with weights about 1 gram of protein per pound of body weight. Protein supplies the construction material (amino acids) for muscle growth and repair.