In recent years, branched-chain amino acid supplements have made a comeback in the bodybuilding and fitness communities, and with good reason. There's more research that supports the use of BCCAs than most other supplements on the market.

While BCAA supplementation may be useful for gaining skeletal muscle (the kind that makes you swole), BCAAs are especially helpful for maintaining mass while on a calorie-deficit diet. They're particularly useful for bodybuilding competitors who take their physiques to the lean extreme.

Although dieting down makes you look awesome onstage, on the beach, and to your friends, it can also take a chunk out of your muscle mass.

How Dieting Can Cause Muscle Loss

Dieting is catabolic, which means it can lead to muscle breakdown, for several reasons. The leaner a body gets, the more likely it is to lose skeletal muscle as the body tries harder and harder to hold on to bodymass. In doing so, a side effect is that the body will turn to muscle to satisfy its energy needs. Bad news for anyone interested in a hard body.

On the molecular level, muscle loss occurs because the body increases protein breakdown (catabolism) in order to liberate muscle amino acids for metabolic fuel. If this isn't bad enough, muscle loss is compounded by the fact that levels of muscle protein synthesis will also decrease due to reduced energy intake.

The basic equation for muscle mass is: Muscle mass = rate of protein synthesis - rate of protein breakdown.

When the rate of synthesis equals the rate of breakdown, you don't gain or lose muscle. If the rate of synthesis is higher than the rate of breakdown, you get muscle growth. When the rate of breakdown is higher than the rate of synthesis, you lose muscle. If you're dieting, you may be burning the candle at both ends: raising muscle breakdown and lowering protein synthesis.

Working out compounds the metabolic effects of dieting. The leaner you get, the more lethargic you can become. Decreased energy intake and glycogen storage make for some rough training sessions. If you're too tired or weak to lift as heavy as your body is used to, your muscles will adapt, and they won't use as much energy to get the work done.

That leads to two metabolic problems: You won't increase skeletal muscle, and your body could use the lean muscle you do have for energy because you aren't using it to lift a heavy load.

How BCAAs Help You Keep Your Muscles

Here are the ways branched-chain amino acids can help you stay swole when you're dieting.

Increase Protein Synthesis

Branched-chain amino acids (which are the essential amino acids valine, isoleucine, and leucine) stimulate muscle protein synthesis, potentially more than a normal protein on its own. Protein synthesis is the metabolic process when your body makes new muscle protein, also known as gains.

Reduce Protein Breakdown

Increased BCAA levels also work in your favor by reducing the rate of protein breakdown. They do this by decreasing the activity of the protein breakdown pathway, and also by decreasing the expression of several complexes involved in protein breakdown. (They decrease the amount of mRNA produced from the gene that codes for these components.)

If we revisit our original equation for muscle mass, it's plain to see that increasing synthesis and decreasing breakdown will equate to muscle gain or maintenance.

Have Better Workouts

Amino acid supplementation could also help you get a more intense workout. Branched-chain amino acids compete with the amino acid tryptophan for entry into the brain, where tryptophan can be converted to the neurotransmitter serotonin.

During exercise, serotonin levels rise and can make you feel more fatigued, meaning you won't be able to push as hard.

BCAA supplementation reduces the amount of tryptophan that gets through the blood-brain barrier, and therefore reduces the amount of serotonin produced. This might allow you to work harder, longer, and get more gains.

BCAAs And Whey

Despite all these benefits of BCAA supplementation, there are many skeptics who say branched-chain amino acids are overpriced and you can just get them from whey protein. While proteins like whey are naturally rich in BCAAs, this isn't the most effective strategy for muscle growth or fat loss.

The BCAAs in whey are peptide-bound to other amino acids. In order to raise BCAA levels in your body, they must be liberated through digestion and then absorbed into the bloodstream. Even though whey protein is relatively fast digesting, it still takes several hours for all the amino acids to be broken down and absorbed into the plasma.

Branched-chain amino acids in supplement form, however, are free-form, require no digestion, and are rapidly absorbed into the bloodstream. They spike blood amino acid levels more quickly and to a much greater extent than peptide-bound aminos in proteins. Even a few grams of free-form BCAAs will spike BCAA plasma levels way more than 30 grams of whey protein. They can start working right away.