One of the more heated debates in sports nutrition circles is whether you need to supplement with branched-chain amino acids (BCAAs) to maximize muscle building, or if you get enough of them through whole foods and protein shakes.

The most often discussed aminos are the three branched-chain amino acids (BCAAs) leucine, isoleucine, and valine. BCAAs are part of a group known as essential amino acids, meaning the body cannot produce them on its own, so they must come from external sources – namely, food.

So, what about BCAA supplements? Worth it or a waste of money? Our go-to sports nutritionist weighs in.

Featured Expert: Susan Lopez, RD, CSSD, LD, is a tactical performance dietitian who specializes in working with athletes from the military, firefighters, police, and first responders. Lopez is a military veteran and special operations spouse whose unique experience and knowledge help elite soldiers and community heroes stay fit and healthy. Do I need BCAAs? If so, how and when should I take them?

BCAAs can definitely be a great addition to a nutrition program, especially for the athlete who’s looking to cut body fat and/or enhance recovery and muscle retention.

The reason BCAAs get so much attention is because they make up a large majority of the amino acids used by the body and have been shown to have the most notable impacts on muscle protein synthesis. Leucine, in particular, is reported to have the greatest effect on muscle protein synthesis, while isoleucine and valine have reported effects on energy and blood sugar regulation, which is essential for fat loss and health in general.

BCAAs typically don’t supply calories to the body like a whole protein would, so they make a great addition to anyone who’s following a calorie-restricted diet for weight or fat loss and would like to ensure that they’re getting enough protein and amino acids necessary for lean muscle retention. For this purpose, they can be taken anytime, but many athletes like to take them immediately before or during workouts. When taken during exercise, they can also help reduce fatigue. This applies not only to resistance training, but to endurance activities as well.

Aside from before and during workouts, when are other good times of day to take BCAAs?

In the grand scheme of things, any time of day is fine to take BCAAs; however, post-workout could be a good time to take in amino acids, since the muscle fibers are primed for protein synthesis due to the stress caused by training. That said, some research suggests that it doesn’t matter if amino acids are taken before or after training, as long as they’re available when the body needs them. In short, hit your daily protein intake from food whenever possible and supplement with BCAAs before, during, or after workouts.

Should I be taking BCAAs on rest days, too?

During a hypertrophy (muscle building) training program — yes, absolutely. The effects of hypertrophy training on the muscles can last 48 hours or more, which may dictate the necessity to have additional amino acids on board. The body is building and repairing even on rest days.

Is there a certain ratio of leucine to isoleucine to valine I should be looking for in a BCAA supplement?

A ratio of 4:1:1 (leucine to isoleucine to valine) is the generally accepted recommendation.

Are there any specific instructions I need to know about when taking BCAAs, or can I just follow the directions on the product container?

For most individuals, following the container instructions is acceptable. Also, BCAAs can safely be mixed with creatine or other supplements you’re taking before, during, or after workouts — for example, a pre-workout that doesn’t include BCAAs.

Other than those who want to get bigger, stronger, and leaner, who else can benefit from BCAAs?

BCAAs have also been used in elderly populations and tactical populations, where lean muscle retention is essential for health and where performance in austere conditions is essential. In general, most populations can benefit from a supplement that contains at least 3 grams of leucine — either on its own or, more commonly, in a BCAA product — to complement a well-rounded diet.

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