BCAAs (short for branched-chain amino acids) may sound exotic, but you consume them every time you eat any food containing protein, including meat, eggs, nuts, seeds, and legumes, says registered dietitian Trista Best, MPH, RD, LD.

Amino acids play roles in functions ranging from organ formation to muscle development and maintenance, and are necessary for healthy skin, hair, and nails. Within this category, BCAAs are particularly important for muscles and the heart, as well as the endocrine and immune systems.

You may have heard BCAAs mentioned in conversations about exercise, muscle building, and supplementation, and wanted to learn more. Learn what BCAAs are and their potential benefits for your fitness regimen.

What Are BCAAs?

Branched-chain amino acids are three of the nine essential amino acids, so called because we can only get them from food as opposed to being produced by the body. They include:

• Valine
• Leucine
• Isoleucine

Found in many foods, including meat, eggs, and dairy products, they’re called “branched chain” amino acids because their chemical structures describe a branching pattern.

Befitting their essential status, BCAAs convey a host of benefits for building and preserving muscle. “BCAAs are believed to reduce muscle degradation and stimulate muscle growth,” says Keith Hodges, an NASM-certified personal trainer in Los Angeles.

“In turn, this can lead to an increase in muscle mass.”

How Do BCAAs Work?

BCAAs work by promoting anabolism, or the synthesis of new tissue. The BCAA leucine, specifically, helps to stimulate this process (a.k.a. build new muscle) through a pathway called mTOR.

“Studies suggest BCAAs may help prevent muscle breakdown during exercise,” says Kristen Smith, M.S., R.D., L.D., and spokesperson for the Academy of Nutrition and Dietetics.

Some research points to this being part of the reason that consuming BCAAs may reduce muscle soreness and damage.

Another way BCAAs might help you recover from a tough workout is by decreasing tryptophan in your brain. Tryptophan can be converted to serotonin, which has been linked to higher levels of fatigue post-workout.

What Are the Benefits of BCAAs?

Branched-chain amino acids are needed for muscle building and maintenance, but that’s not all.

1. May help build muscle

BCAAs support anabolism, which is the process by which new tissue, including muscle, is synthesized. The BCAA leucine is especially beneficial for stimulating protein synthesis (i.e., the building of new muscle).

“Supplementing with BCAAs is not only beneficial for gaining muscle, but also preventing muscle loss,” Best says.

Several studies have found that supplementing with BCAAs can help reduce muscle atrophy (loss) in older adults.

And a 2016 study found that BCAAs taken alongside a resistance training program helped preserve lean body mass in people who were on a reduced-calorie diet.

3. Appetite and Weight Management

Branched-chain amino acids, especially leucine, have been shown to help decrease appetite and thus could potentially help with weight loss.

Protein in general is among the nutrients that keep us feeling full the longest, and is a source of BCAAs, so your best bet is to ensure you’re including some source of protein in the majority of your meals.

4. May help aid post-workout recovery

A 2017 study found that endurance athletes who supplemented with BCAAs had lower levels of the muscle damage markers creatine kinase and lactate dehydrogenase in their blood after two hours of cycling.

And a 2021 meta-analysis published in the Journal of Sports Medicine and Physical Fitness looked at 19 studies on BCAAs and found that BCAA intake can help reduce exercise-induced muscle damage.

5. May help reduce muscle soreness

A 2019 meta-analysis of eight studies found that BCAA supplementation after exercise resulted in a “large decrease in DOMS [delayed onset muscle soreness]” compared to placebo.

How Much BCAA Per Day Should You Take?

There are no official recommendations for BCAA intake, and the optimal amount for supplementation is not known. However, some studies show that taking supplemental BCAAs helps with muscle building and reduces post workout fatigue.

“As with any supplement,” says Melissa Majumdar, MS, RD, CSOWM, LDN, and Academy of Nutrition and Dietetics media spokesperson, “you should consult a registered dietitian nutritionist to decide if they are a good fit. Consumption of carbohydrates during exercise can help maintain the tryptophan (another amino acid) and BCAA ratio, thus helping avoid central nervous system fatigue.”

What Foods Contain BCAAs?

The foods that are especially high in BCAAs include:

• Chicken
• Meat
• Salmon
• Beans and lentils
• Cottage cheese
• Milk
• Tofu
• Tempeh
• Eggs
• Quinoa
• Nuts

BCAAs are well-absorbed and very bio-available when consumed from whole foods.

Are There Side Effects of BCAAs?

Majumdar says that any potential side effects “are generally mild.” These can often range from nausea to stomachaches.

The Bottom Line About BCAAs

Getting BCAAs from complete protein sources such as meat, fish, dairy and tofu is doable for most people and even pro athletes, as those sources contain all the essential amino acids.

If you are unable to eat enough protein, or if you have certain medical issues, talk to your doctor or dietitian, who might recommend that BCAA supplementation may be beneficial.