HMB Is Making A Comeback—Here’s Why

This article originally appeared in Muscle & Performance magazine. 

Can you shed body fat while holding onto muscle mass? If you strategize and supplement correctly, you can.

Intermittent fasting is one of the fastest growing diet trends for fat loss out there. However, it generally means going 12 to 24 hours without ingesting calories of any kind. Millions of people have benefited from the rapid weight loss associated with intermittent fasting, but when you restrict nourishment—especially protein and amino acids—for hours, you run the risk of elevating cortisol (the ‘stress hormone’) and putting the body in a state of catabolism (or breakdown), potentially endangering your hard-earned gains.

One familiar product, however, could very well be your key to avoiding undue muscle loss. A recent study published in the British Journal of Nutrition suggests that β-hydroxy-β-methylbutyrate— commonly known as HMB free acid (HMB-FA)—may be an ideal supplement for those who partake in intermittent fasting.

HMB, which is found in foods like avocado, alfalfa, catfish, and citrus fruits, is an active anabolic metabolite of the essential branched-chain amino acid leucine, which resides in all human muscle cells.

In the study, researchers from Texas Tech University assessed the effects of HMB-FA supplementation on catabolism (muscle breakdown), cortisol release, testosterone, and resting energy expenditure during a period of acute fasting. Eleven healthy men and women participated in the double-blind, placebo-controlled experiment, during which they received either an HMB-FA supplement or a placebo while undergoing a three-day meat-free diet, followed by a 24-hour fast.

Interestingly, markers of catabolism were unaffected by the fast, meaning HMB didn’t seem to directly impact muscle breakdown. However, the fasting cortisol response of those supplementing with HMB was blunted by a whopping 32 percent, while no change occurred in the placebo group. This reduction in cortisol allowed for a 162-percent increase in the participating men’s testosterone-to-cortisol ratios, a key factor in their ability to maintain and build muscle.

Take Your Intermittent Fasting With A Side Of HMB

If you’re using intermittent fasting as a dieting strategy, or just want to keep cortisol levels in check, it seems that HMB-FA might provide some supplemental support. Research suggests the best dose for HMB is 38 milligrams per kilogram of body mass (about 17 milligrams per pound) daily, split into three equal doses. BodyTech’s HMB provides about 250 milligrams per capsule.

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Take one dose 30 to 60 minutes before training, another immediately after training, and the final dose with a meal. On rest days, take your three doses with breakfast, lunch, and dinner. Chronic consumption of HMB has been deemed safe, and you’ll notice its full effect after about two weeks of supplementation.