What is HMB and Why Does It Matter to Your Muscles?

In the land of bodybuilding supplements, creatine and protein stand together at the top of the mountain, both in terms of popularity and research-backed results. In the battle for third place behind those two behemoths, beta-hydroxy beta-methylbutyrate (HMB), once threatened to snag a huge portion of the supplement marketplace.

HMB first came on the scene in the mid 1990s, promising gains in lean mass, help with fat loss, and improved recovery from workouts. After a blip of hype, HMB faded into the background, maybe because of high prices or unrealistic expectations, or maybe because that was about the time that the steroid precursors like androstenedione came into vogue.

Whatever the reason for its market “failure,” HMB is still around, and its makers still trumpet its benefits.

But can HMB really help you build muscle?

In order to understand the truth about what HMB can offer you, it’s important to first understand what it does and how it functions.

What Is HMB?

In simplest terms, HMB is a metabolite of the essential amino acid leucine — HMB is created as a byproduct when our bodies break down leucine.

Leucine is one of three branched-chain amino acids (BCAASs), with valine and isoleucine being the others. The BCAAs have been shown to limit the muscle breakdown associated with hard training, particularly when you are on a restricted diet, like when you’re trying to get ripped. The usual recommendation is to take the aminos before training to help head off potential catabolism.

Leucine in particular has been found to play an important role in enhancing protein synthesis, and it is also a precursor to glutamine, the most abundant amino acid in our bodies. Like the other BCAAs, leucine also has powerful anti-proteolysis (muscle burning) effects.

Detailed research has found that those anti-catabolic properties of leucine may  actually be due largely to one of its metabolites — HMB.

What Can HMB Do for You?

So, HMB helps prevent protein  breakdown, which can be a huge boost to your overall muscle mass when you’re training hard or dieting — or the combination. Both intense workouts and low-calorie eating plans place a lot of stress on your body and tend to promote the use of muscle tissue for energy and to help you “survive.” Your body is very efficient in keeping you alive, and it will try to get rid of anything it doesn’t need and that burns precious calories when it perceives a crisis.

The stress of training and dieting is that crisis, and your (hopefully) bulky muscles are the unnecessary calorie burners. HMB can help turn that situation around and aid you in maintaining your mass.

Beyond anti-catabolic properties, HMB has also been shown to boost  protein  synthesis, though to a lesser degree than leucine itself.

In a more practical sense, HMB has been found in clinical studies to produce direct benefits to hard-training athletes. For example, researchers from Brazil found in 2001 that middle-aged men taking HMB in conjunction with a weight training program experienced a significant reduction in “bad” (LDL) cholesterol while improving lean body mass and strength over the course of four weeks.

An earlier (1996) study out of Iowa found similar results and noted that supplemental HMB tends to reduce the extent of proteolysis associated with resistance training.

How to Get Yours

While you can get leucine, and therefore HMB, from a normal diet, studies like those above indicate it may take as much as three grams per day of HMB to see significant benefits. The typical diet, on the other hand, provides less than 0.5 grams per day even when the focus is on protein and muscle-building.

Those numbers point to supplemental HMB being your best bet if you’re hoping to see a boost in recovery and muscle growth. There are several different products on the market that would fit that bill, usually in the form of pills or powders, and HMB is much less expensive than it was 20 years ago.

Of course, taking large doses of any one nutrient comes with the risk of unwanted side effects. Even though nothing in particular has been identified with regard to short-term HMB supplementation, you definitely need to speak to your physician before undertaking a program that includes extra HMB.

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