Fat Burning

HMB: An Old Dog With New Tricks!

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


Intermittent fasting is one of the fastest growing diet trends for fat loss. 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 without protein or amino acids for hours, you run the risk of elevating cortisol (a catabolic hormone) and putting the body in a state of catabolism — 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, 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 aforementioned 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 during a three-day meat-free diet, followed by a 24-hour fast.

Interestingly, markers of catabolism were unaffected by acute fasting, so there was no observed impact of HMB on muscle breakdown. However, with HMB supplementation, the fasting cortisol response was blunted by a whopping 32 percent, with no effect evident in the placebo group. In males, testosterone-to-cortisol ratios increased 162 percent from 0 to 24 hours of fasting with HMB-FA, mainly because of reductions in cortisol.

Action Point: If you’re using intermittent fasting as a dieting strategy or if you just want to keep cortisol levels in check, it seems that HMB-FA might provide some supplemental support. According to research, the best dose for HMB is 38 milligrams/kilograms of body mass daily (about 17 milligrams/pounds of bodyweight), split into three equal doses. Take one dose 30 to 60 minutes before training, another immediately after training and another with a meal. On rest days, take your three doses with breakfast, lunch and dinner. You’ll notice the greatest effects of HMB after two weeks of supplementation and chronic consumption is deemed safe.