Branched-Chain Amino Acids (BCAAs)
Technically, BCAA's increase muscle protein synthesis. Practically speaking, supplementing BCAAs doesn't have any useful effect because every time you eat something with protein in it, you’re already consuming BCAAs. Common protein sources for lifters, such as whey or meat, are typically quite high in BCAAs.
They can be beneficial if you work out while fasting, but since eating a little bit more protein at your next meal is nearly as effective, it’s cheaper and easier to stick to real food.
There are two very important points you’re not told about BCAA research:
1. Research commonly cited that demonstrates muscle-related benefits of BCAA supplementation was done with subjects that didn’t eat enough protein.
For example, this study is one of the main articles for selling BCAAs. It investigated the effects of BCAA supplementation on a group of wrestlers in a calorie deficit. After three weeks, the supplement group, who ingested an additional 52 grams of BCAAs per day preserved more muscle and lost slightly more fat than the control group (who didn’t supplement at all).
Supportive evidence, right? Well, what you won’t hear is that subjects, whose average weight was about 150 pounds, were eating a measly ~80 grams of protein per day. If we look at research on the protein needs of athletes in a calorie restriction, we learn that they should have been eating double that amount of protein to preserve lean mass.
So all that study really tells us is if we feel like eating half the amount of protein we should be eating, a BCAA supplement can help mitigate the damage.
Other studies that demonstrate various muscle-related benefits of BCAA supplementation have promising abstracts, but are almost always hampered by lack of dietary control and/or low protein intake, and in almost all cases, subjects are training fasted, which is a very important point we’ll talk more about in a minute.
2. You can simply get your BCAAs from food instead, and this is cheaper and far more satisfying.
What such research tells us is that acutely raising BCAA levels before and after exercise helps us build more muscle. There is no evidence that doing it through the ingestion of a BCAA supplement is more effective than food, however.
So that’s how things currently look when we strip away the hype and marketing angles.
Okay then, so BCAAs don’t look to be nearly as exciting as the supplement companies say. They do, however, have one scientifically validated, legitimate use…
Bcaa's and fasted training
If you were on the fence about buying a BCAA supplement, you’re probably off it now. It turns out, however, that this supplement does one scientifically supported use, and it relates to fasted training.
People usually think “fasted training” means “training on an empty stomach,” but it’s a bit different. Fasted training means training in a “fasted state,” and this relates to insulin levels in your blood.
When you eat food, it gets broken down into various molecules that your cells can use, and these molecules are released into your blood. Insulin is released as well, and its job is to shuttle these molecules into cells.
Now, depending on how much you eat, your plasma (blood) insulin levels can remain elevated for several hours (anywhere from 3 – 6+). Why is this important? Because insulin blocks lipolysis (the breakdown of fat cells in the body).
When your body is in this “fed” state–when its insulin levels are elevated and its absorbing nutrients you’ve eaten–little-to-no fat burning occurs.
Your body enters a “fasted” state when it has finished absorbing all the nutrients from the food you’ve eaten and insulin levels return to their normal, low “baseline” levels.
When you exercise your body in this state, fat loss is accelerated.
So, as you can see, just feeling like you have an “empty stomach” doesn’t necessarily mean your insulin levels have returned to baseline.
The easiest way to work fasted training into your routine is to work out first thing in the morning, before you eat breakfast.
There is a downside to fasted training, however, and this is where we get to BCAAs.
When you exercise in a fasted state, muscle breakdown is increased and this is bad simply because too much muscle breakdown impairs total muscle growth over time.
You can prevent this with proper supplementation, however.
As BCAAs include leucine, and as leucine suppresses muscle breakdown, a BCAA supplement is useful for preserving muscle while training in a fasted state.
And in case you’re wondering why you can’t just use food, remember that food will spike your insulin levels and you will no longer be in a fasted state. In fact, whey protein is more insulinogenic than white bread.
BCAAs, on the other hand, have a smaller impact on insulin levels than food, which allows you to remain in a fasted state while you train. This is why many people “in the know” supplement with BCAA's before fasted exercise.