You should know by now that the amino acids the body gets from food are critical to building muscle — along with just about every other tissue in the body. But not all aminos are created equal. The branched-chain amino acids are the three most important amino acids for building muscle. That’s why you hear so much about them and why they’re available in so many different supplements. But these three powerful aminos do far more than just grow muscle. They also play a major role in boosting energy levels, delaying muscle fatigue and even aiding fat loss.
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The BCAAs are three essential amino acids: leucine, isoleucine and valine. From a chemical structure standpoint, each of them has a forked outcropping that looks a lot like a branch, hence their name. But what makes the BCAAs so special is how the body handles them.
Out of the 20 amino acids required for muscle growth, 17 of them are only used to build muscle. The three branched-chain amino acids (valine, leucine, isoleucine), however, are used for building muscle and for energy. That’s both good and bad — good because BCAAs are an immediate energy source for muscles; bad because BCAAs are absolutely critical to muscle growth, so if you’re using them all for energy, there won’t be any left for that. This is why it’s critical to stock up on BCAAs before and after workouts: They will supply more fuel and therefore prevent the BCAAs that are already stored in the muscle tissue from being broken down, and there will be more BCAAs available for building more muscle tissue after the workout is over. But acting as a direct energy source for muscles is not the only way that BCAAs boost your workout intensity. They also work in the brain to delay fatigue.
During exercise, a metabolite of the amino acid tryptophan known as 5-hydroxytryptamine signals the brain that the body is fatigued, which leads to a reduction in muscle strength and endurance. But research has discovered that taking BCAAs before workouts lessens the amount of tryptophan that can get into the brain — less tryptophan, less 5-HT, less fatigue. That means you’re capable of longer, more intense workouts, but it also means that your brain will remain sharper and more focused.
Lastly, BCAAs have recently been found to increase a different type of endurance — life span. Researchers from Milan, Italy, discovered that mice that were given BCAAs in their drinking water had higher amounts of mitochondria in their muscles, higher activity of the longevity gene, SIRT1, and lived 12 percent longer than those not getting BCAA-enriched water. So supplementing with BCAAs daily can keep you going longer in the race we call life.
The BCAAs gained their popularity with bodybuilders because of their ability to directly increase muscle size. As you likely know, muscle is made of protein. And protein is made up of amino acids strung together like a pearl necklace. So the way that muscle grows is by stringing together amino acids to make more protein, a process that is scientifically known as muscle protein synthesis. Although the three BCAAs are critical aminos in the strings of proteins that make muscle, their role in muscle building is much more than just serving as building blocks.
Research has discovered that the BCAAs, particularly leucine, increase muscle growth by directly stimulating muscle protein synthesis. Leucine acts like a key that turns on the process that strings the amino acids together to build muscle protein. Additionally, leucine boosts levels of insulin, the anabolic hormone that further stimulates protein synthesis but via a different mechanism than leucine.
BCAAs also work to enhance muscle growth and strength by boosting levels of growth hormone. Italian researchers found that athletes taking BCAAs for one month had higher levels of growth hormone after workouts. The higher the GH levels after workouts, the greater the increases in muscle size and strength.
Yet another hormone that BCAAs influence is cortisol, the catabolic hormone that interferes with the anabolic hormone testosterone and encourages muscle breakdown. Fortunately, BCAAs have been shown to blunt cortisol during exercise. This could be why numerous studies have confirmed that athletes taking BCAAs have significantly less muscle breakdown and better muscle recovery after exercise.
In essence, the BCAAs promote muscle growth and strength through five different mechanisms: 1) serving as the building blocks to make muscle protein, 2) directly activating the process that turns on protein synthesis, 3) indirectly activating protein synthesis through insulin, 4) elevating GH levels and 5) lowering cortisol levels. Now you can understand why it’s so important to take BCAAs after every workout. In fact, a study performed by the Weider Research Group and reported at the 2009 annual meeting of the International Society of Sports Nutrition found that trained lifters taking a BCAA supplement around workouts for eight weeks gained about twice as much muscle and strength as those taking a whey protein shake without additional BCAAs.
The BCAAs are not just great building supplements; they also can aid fat loss. One of the first studies to discover this benefit was one conducted in 1997 on competitive wrestlers that found that those who supplemented with BCAAs while following a low-calorie diet experienced a greater drop in body fat, particularly in the waist, as compared to those taking a placebo. The Weider Research Group study mentioned above also found that those lifters taking BCAAs lost about twice as much body fat as those taking whey protein without added BCAAs. Although its uncertain precisely how the BCAAs aid fat loss, there are some theories.
A study out of Brazil found that six weeks of leucine supplementation caused a large drop in body fat. The researchers proposed that the increase in protein synthesis stimulated by leucine increased energy expenditure so much that it helped burn off body fat. Leucine also has been found to reduce hunger, causing you to eat less while you burn more, which ultimately leads to fat loss. In the most recent study on BCAAs’ fat-loss effects, Japanese researchers discovered that mice given isoleucine while eating a high-fat diet gained significantly less fat than mice not getting supplemental isoleucine. This was because of isoleucine’s ability to activate special receptors, known as PPAR, that increase fat burning and inhibit fat storage.
Each time you take BCAAs, you should take 5 to 10 grams. The most critical time to take them is around workouts. So be sure to add 5 to 10 grams to your preworkout and postworkout shakes. Also consider taking a dose of BCAAs first thing upon waking to help stop the muscle breakdown that is turned on during your night of fasting while you sleep. You also can take a 5- to 10-gram dose of BCAAs at any other time of day to get an energy boost, reduce hunger and aid muscle growth.