by Layne Norton Bodybuilding.com
In recent years, branched chain amino acid supplements have come back into 'vogue' in the bodybuilding and fitness community, and with good reason. There's more research that supports the use of BCAAs than most other supplements on the market!
While BCAA supplementation may be useful for gaining mass, I believe BCAAs are especially helpful for maintaining muscle 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 of the opposite sex, it can also take a chunk out of your muscle mass.
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 muscle mass as the body tries harder and harder to hold onto body fat stores. In doing so, the body will turn to muscle to satisfy its energy needs. Bad news bears 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 fuel. If this isn't bad enough, muscle loss is compounded by the fact that levels of 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 exceeds the rate of breakdown, you gain muscle. When the rate of breakdown exceeds the rate of synthesis, you lose muscle. If you're dieting, you may be burning the candle at both ends: elevating muscle breakdown and reducing protein synthesis.
Working out compounds the metabolic effects of dieting. The leaner one becomes, the more lethargic one can become. Decreased energy intake and decreased glycogen storage make for some rough training sessions. If you're too tired or weak to lift as heavy as your body was getting used to, your muscles will adapt, and they won't use as much energy to get the work done.
That means your body won't increase lean muscle mass; it might also mean that your body will use lean muscle for energy because you aren't using it to lift a heavy load.
The Beauty of BCAAs
How do you defend against this three-headed monster of muscle loss? Attack all three heads!
It's well established that branched chain amino acids (particularly leucine) stimulate protein synthesis, and might do so to a greater extent than a normal protein on its own. BCAAs also increase synthesis of the cellular machinery responsible for carrying out the process of protein synthesis. Thus, BCAAs not only increase the RATE of protein synthesis, but they also increase the cell's CAPACITY for protein synthesis! Yep, you read that right.
BCAAs also work in your favor by reducing the rate of protein breakdown. They do this (primarily) by decreasing the activity of the components of the protein breakdown pathway, and also by decreasing the expression of several complexes involved in protein breakdown. (In this case, 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/maintenance. And THAT, my friends, is how we fight the Cerberus of muscle loss.
Even More Beautiful
BCAAs have even more positive benefits than reduced breakdown and increased protein synthesis. They might also help improve workout intensity! BCAAs 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 (amongst other things) increase the perception of fatigue -- that means a less intense workout for you.
BCAA supplementation reduces the amount of Tryptophan that enters the brain, and therefore reduces the amount of serotonin produced. This might allow you to work harder, longer.
BCAAs And Whey
Despite the numerous positive benefits to BCAA supplementation, there are many skeptics who suggest that BCAAs are overpriced and that, to get more BCAAs, one should just consume more whey protein. While whey is rich in BCAAs, this isn't the most effective strategy.
The BCAAs in whey are peptide-bound to other amino acids and, in order to be effective, 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 liberated and absorbed into the bloodstream.
BCAAs in supplement form, however, are free form, require no digestion, and are rapidly absorbed into the bloodstream. They spike blood amino acid levels to a much greater and faster extent than peptide-bound aminos. Even a few grams of free-form BCAAs will spike BCAA plasma levels to a much greater extent than a 30g dose of whey protein, thereby impacting protein synthesis and protein degradation to a much greater degree.
The reason BCAA supplements have such a powerful effect on blood BCAA levels is that, is that unlike other amino acids, BCAAs are not significantly metabolized by the small intestine or the liver. Therefore, an oral supplement is more like a BCAA infusion because it reaches the bloodstream so rapidly.
The Bottom Line
New studies have shown that dieting groups supplementing with BCAAs (like leucine) increase muscle retention and maximize fat loss much more effectively than non-supplemented groups. That's the bottom line, my friends: more muscle mass retained, and a greater percentage of lost body fat.
Forget other supplements that are long on promises but short on results. Instead, check out the power of BCAAs.
Further BCAA-Related Reading:
Am J Physiol Endocrinol Metab. 2012 Mar;302(5):E510-21. Epub 2011 Nov 29.
J Nutr. 2006 Feb;136(2):529S-532S.
Current Therapeutic Research 2000 61(1): 19-28.
J Nutr. 2010 Mar; 140(3): 496-500.
Int J Sports Med. 2007 Jun;28(6):531-8.
J Nutr. 2006 Feb; 136(2): 548S-552S.
J Nutr. 2006 Jan; 136 (1 Suppl): 264S-8S.
Muscle Nerve. 2010 Jun; 41(6): 800-8.
Am J Physiol Endocrinol Metab. 2005 Apr; 288 (4): E645-53.