If you’re reading this, you probably already know that amino acids are the building blocks of protein. And, you’ve probably heard a thing or two about the branched-chain amino acids (a.k.a. BCAAs), leucine, isoleucine, and valine, which are named for their branch-chain molecular structure.

In addition to powering up with protein powder, many fitness enthusiasts take a BCAA supplement to maximize their workouts. That’s because BCAAs help prevent the breakdown of muscle protein, which is important for recovery and building muscle mass, explains Washington-based dietitian Kristin Koskinen, R.D.N.

“Most amino acids are metabolized in the liver, but BCAAs bypass the liver and go directly to muscle,” she says. “Since BCAAs inhibit the stress hormone cortisol, which can lead to muscle breakdown, they may contribute to speedier muscle recovery.”

Another reason BCAAs have become so popular is that they may help you reach your body composition goals, per a 2015 study published in Nutrients. “They aren’t a magic bullet, but as part of a program that includes proper diet and exercise, BCAAs may support muscle mass and weight management,” Koskinen says.

Since BCAAs occur naturally in food (specifically in animal-based proteins), it’s possible to get enough through diet, says Rob Sulaver, C.S.N, C.S.C.S., creator of Bandana Training and founding trainer at Rumble Boxing. However, there are certain cases in which a BCAA supplement comes in really handy. Here are seven to consider.

1. You want to bulk up your muscle mass

Because one-third of muscle protein is composed of BCAAs, gains require adequate BCAA consumption, according to The Vitamin Shoppe nutritionist Rebekah Blakely, R.D.N. In fact, one Journal of Nutrition review found that BCAAs successfully activate enzymes involved in building muscle.

“BCAAs are most often available in a 2:1:1 ratio of leucine-isoleucine-valine, based on recommended doses,” Blakely explains. “The recommended dose of leucine is typically two through 10 grams per day, so combined doses of up to 20 grams daily may be beneficial.”

2. You’re participating in an endurance Race, such as a marathon

After winning over the gym-goer community, BCAA supplements are now gaining popularity amongst endurance racers, explains Roger E. Adams, Ph.D., owner of eatrightfitness.

“The training involved in these sports can be quite harsh on the body and requires many repetitive hours over many weeks and months,” he says. “BCAA supplementation does seem to improve recovery and decrease the soreness associated with these long training sessions.”

To promote muscle recovery, Adams recommends endurance athletes take 2.5 grams of BCAAs prior to and during training (so five grams total).

3. You don’t feel hydrated before working out

Although more research needs to be done, one Nutrition Journal study suggests that BCCAs may play a role in enhancing hydration.

Read More: 8 Fun Ways To Drink More Water If You Hate Water

“Having BCAAs before your training sessions as part of your hydration strategy is a good way to ensure you get the fluids you need and set the stage for recovery,” he says.

4. You’re doing fasted workouts

If you’re exercising first thing in the morning or going many hours without eating, a BCAA supplement can help replenish some of the building blocks you’ve depleted but need in order to perform and recover at your best, says The Vitamin Shoppe nutritionist Brittany Michels, R.D.N. So, if you work out before breakfast and find yourself feeling tired, or are concerned about your muscle recovery afterward, sip on BCAAs while you sweat.

5. You cannot get to a post-workout meal within an hour

If you won’t have access to protein post-workout, you’ll benefit from taking a BCAA supplement.

“If it’s going to be longer than 30 to 60 minutes after a workout before you can get some nutritional recovery, you may want to supplement with BCAAs to help your muscles do recovery work in the meantime,” says Blakely.

6. You struggle to consume enough protein on a daily basis

If you don’t consume enough protein through food, you may lack essential amino acids, according to Blakely. “Not getting enough protein can be a common issue among plant-based eaters and the elderly (who tend to have decreased appetites),” she says. “Supplementing with BCAAs can help you meet those essential amino acid needs to help fuel activity and minimize muscle breakdown.”

Read More: 9 Easy Ways To Increase Your Protein Intake

Individual needs vary, but if this is a concern for you, Blakely recommends taking closer to 10 to 20 grams of BCAAs daily.

7. You’re going to be working out for longer than 90 minutes

According to Blakely, most people burn through their nutritional stores within about 90 minutes of activity, depending on intensity level. For this reason, if you’re doing a long workout, she recommends a BCAA supplement, which can provide essential nutrients to your muscles that may potentially minimize fatigue.

Blakely recommends taking at least five to 10 grams of BCAAs throughout the workout, followed by 20 to 30 grams of post-workout protein, plus an additional five to 10 grams of BCAAs for replenishment.