Wednesday, July 27, 2011

EAT TO GROW : HMB Gets an F..New study gives the supplement a failing grade by Jerry Brainum

Beta-hydroxy-Beta-methylbutyrate (HMB) may work better on paper than it does in the real world. HMB is a metabolite of the branched-chain amino acid leucine, and several studies show that it should provide impressive benefits to anyone engaged in weight training. In fact, a recent meta-analysis, or analysis of many previous studies, examined the accumulated evidence of efficacy for about 250 popular bodybuilding supplements and found acceptable scientific evidence for only two: creatine and HMB. Unfortunately, the primary author of that review is also the same person who discovered HMB.

HMB is found in several foods, such as catfish and grapefruit. The body synthesizes it from leucine; the higher the leucine intake, the greater the synthesis of HMB. A 150-pound man would synthesize about 200 to 400 milligrams a day, depending on leucine intake. Several studies have shown that HMB appears to promote lean-mass gains while speeding fat loss, an ideal combination for bodybuilding purposes.

But not all studies have found such beneficial effects. A study of HMB use among more experienced weight trainers found no evidence of any gains in lean mass whatsoever. The latest study focused on HMB’s effects in hard-training college football players.1

Thirty-five athletes worked out an average of 20 hours a week doing weight training and aerobics, as well as skill exercises. During the first part of the study, 16 of the subjects took three grams of HMB a day, while 19 took a placebo. After a week long washout period, during which no supplements were taken, the groups switched, with those who had taken the placebo going on genuine HMB, three grams a day, and vice versa.

After nine weeks those who took HMB showed no gains in strength or any loss of bodyfat, compared to the placebo group. A curious aspect of this study, however, was the athletes’ unusually low calorie intake. They averaged only 2,600 calories a day, not a huge amount for hard-training football players. The authors also suggest that the athletes may well have overtrained, which may have obscured any benefits from HMB.

Judging by this study, HMB doesn’t offer much benefit to those engaged in intensive training. On the other hand, results obtained from previous studies of HMB show that it’s most efficiently used either at the beginning of a weight program or when you’ve significantly increased the workload.There is also some emerging evidence that HMB may be of use to prevent excessive muscle loss in older people, a condition known as sarcopenia. HMB does appear to blunt an established pathway of muscle catabolism.

1 Ransone, J.R., et al. (2003). The effect of B-hydroxy-B-methylbutyrate on muscular strength and body composition in collegiate football players. J Strength Cond Res. 17:34-39.

©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.

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