HMB (beta-hydroxy beta-methylbutyrate)
HMB is a metabolite of the branched-chain amino acid leucine. HMB is found in foods of both plant and animal origin, and HMB is also normally produced in the body. Depending on the nutritional program, 0.3 grams to 1 gram of HMB is produced in the body per day. Certain plants such as alfalfa and plant products such as corn silage appear to have relatively large concentrations of HMB. Grapefruit and catfish also contain relatively high concentrations of this nutrient. However, similar to various vitamins and other micronutrients, it is extremely difficult and impractical to consume enough of these foods on a regular basis to provide the full benefits of HMB. It is probably much more practical to use a dietary supplement containing pure HMB. Sadly, HMB production has been discontinued for use as a food supplement, just like GABA.
Researchers are not completely certain how HMB works in the body. It appears that this amino acid metabolite supports the body’s ability to minimise protein breakdown subsequent to stress such as intense exercise and it also may work to preserve the integrity of cell membranes; hence the associated “anti-catabolic” label. By minimising protein breakdown, HMB, when combined with a resistance-training program, may cause an increase in muscle mass and strength. HMB has been extensively studied by doctors and researchers. Many species of animals have been studied while using HMB to examine the safety and effectiveness of the compound, and toxicity studies to date suggest that HMB is safe for human use. In one study, which involved people who participated in a “weight-training-like” workout, test subjects who used three grams of HMB a day gained much more lean mass and experienced significantly greater strength gains, in just three weeks, than those who did not use the product. Some professional athletes (especially body-builders) refer to HMB as “human muscle builder”.
It’s probably important to continue taking HMB even on your “off” days as not only does HMB play a role in “protecting” your muscles from excessive damage, it may also aid in the growth and repair of muscle tissue during your days away from the gym. If you avoid taking HMB on these days, you may be missing the opportunity to boost your recuperative abilities.
However, it may make sense to take less HMB on non-training days. Some anecdotal and research-based information seems to indicate that it may be beneficial to take more HMB than the recommendation of three grams per day. Some athletes have experienced improved results from as much as five grams per day. Experts have speculated that the improved benefits of higher dosages may be due to the bodyweight of these weight-training athletes, as many of them weigh much more than 200 pounds. So if you’re well over 200 pounds, a sample HMB dosing schedule may be trying five or six grams on training days and two to three grams on off days.
Although the total amount of HMB may be reduced on non-training days, it’s important to increase the frequency of HMB supplementation to maintain a consistent blood level and thereby potentially increase its effectiveness. For example, you might try consuming a half-serving of HMB five or six times a day rather than a full serving three times a day.