Wondering what these amino acids things are that everyone's talking about? Get to know the building blocks of your protein

By Dr. Mike Roussell
October 21, 2014
Photo: itakdalee/Getty Images

Q: What are the muscle-building benefits of amino acids, especially the buzzed-about BCAAs (branched-chain amino acids)?

A: Amino acids are the building blocks that make up protein. Your body puts them together like Legos to create muscle. While your body can make some from scratch (called non-essential amino acids), you have to obtain others (essential amino acids), from food or supplements. These essential amino acids-especially a certain kind called branched-chain amino acids (BCAAs)-are the limiting factor in your body's ability to build muscle. Here's more on what the BCAAs are, the benefits of BCAAs, and how to get them into your diet.

Whether you're trying to shed pounds or beat your PR, increasing your muscle mass is essential, since it's key to both weight loss and performance. Also, muscle is built very, very slowly. While fat loss can be easily accelerated, muscle building cannot. (Here's all the science on how to build muscle and burn fat.)

Bonus: Muscle burns calories all day long-meaning you'll burn more calories when exercising and you'll burn more calories sitting on the couch (score!). Even if you aren't trying to add more muscle, you break down muscle during exercise that needs to be rebuilt so that you can work out again the next day. Which is why, whatever my clients' goals may be, we always put a priority on maintaining the muscle they have and potentially building up more-which requires getting enough protein and the right amino acids. (And, also, one reason why you should lift heavier weights.)

The Benefits of BCAAs

There are three types of BCAAs: leucine, isoleucine, and valine. They are called branched-chain amino acids because their chemical makeup has a unique branched structure (like a tree branch). This gives them some interesting abilities that no other amino acids have.

One big perk of BCAAs is that they help prevent muscle breakdown. They help increase the rate in which your body can build proteins so you aren't breaking down muscle faster than you can rebuild. Leucine is the key BCAA in this process. (Here's more on why leucine is so important for maintaining and building muscle.)

BCAAs also provide fuel for exercise. During an intense workout, the unique structure of BCAAs allows them to act as fuel for your muscles. And finally, they may help you slim down: Several studies show a relationship between BCAA intake and leanness, and high intakes of BCAAs are generally associated with a leaner body.

Sources of BCAAs

1. BCAA Supplements: Drinks with BCAAs have become very popular and come in lots of great citrus and fruit flavors that don't taste like you're just drinking protein. These products are fine to use right after exercise or during long training session (over 90 minutes). However, there isn't a lot of scientific evidence to support unique benefits of pure BCAA supplements over other protein drinks or foods that has similar amounts of these amino acids, so don't feel like you have to use a BCAA supplement. (Related: Your Complete Guide to Pre- and Post-Workout Supplements.)

2. Whey protein or chocolate milk: A simple shake with whey protein will deliver all the BCAAs that you need along with all the other essential amino acids to round out your muscle building and recovery efforts. Or you can simply have a glass of chocolate milk to serve as your nutritional recovery aid. Milk is naturally loaded with BCAAs and the little added sugar from the chocolate will further aid in recovery after a longer exercise session.

3. Whole foods: Fish, eggs, lean beef, chicken, and turkey all contain ample amounts of these key amino acids. (Plant-based sources are often considered incomplete proteins, but you can combine them to create complete proteins.)

4. Pea or rice protein: Plant protein is generally lower in BCAAs, but pea protein is an exception in this area. Just make sure to take in more total protein to get all the essential amino acids your body needs. One study published in Nutrition Journal found that 40g of rice protein worked just as well as 40g of whey protein when it came to improving body composition. But when calories are at a premium, whey becomes the superior post-workout choice as you could most likely get a similar effect as shown in the study with half the amount of whey (20g) than you would obtain with rice protein due to the lower proportion of essential and branched chain amino acids. (​Related:The Best Protein Powders for Women.)