Branched-chain amino acids (BCAAs) are a group of three essential amino acids: leucine, isoleucine and valine. BCAA supplements have become incredibly popular among bodybuilders and athletes for their purported effects on muscle growth and performance.
However, some people wonder whether BCAAs contain calories. This article will provide a detailed look at BCAAs and whether or not they contain calories.
What are BCAAs?
The three BCAAs — leucine, isoleucine and valine — make up around one-third of the amino acids found in muscle proteins. They are considered essential because your body cannot produce them on its own. You must obtain them from food sources (1).
Leucine, in particular, plays a key role in muscle protein synthesis, while isoleucine and valine appear to have supportive roles (2).
Together, these three amino acids promote muscle growth, decrease muscle soreness and exercise fatigue, and improve exercise performance and recovery (3, 4, 5).
BCAA supplements provide these amino acids in an isolated form, rather than as part of a complete protein source like eggs or meat.
Do BCAAs contain calories?
Yes, BCAAs contain calories like all other amino acids.
One gram of BCAAs provides approximately:
- Leucine: 4 calories
- Isoleucine: 4 calories
- Valine: 4 calories
So 1 gram of BCAA powder contains around 12 calories. A typical 5-gram serving of BCAAs contains 60 calories (6).
While BCAA supplements do contain a minimal amount of calories, their calorie content is negligible compared to your total daily calorie intake.
For example, a 125-pound (57-kg) person requires around 1,400 calories per day to maintain their weight. Just 5 grams of BCAAs would contribute only 4% of their total calorie needs for the day.
BCAAs stimulate muscle protein synthesis
The primary benefit of BCAA supplements is that they stimulate muscle protein synthesis (MPS), which is the process of generating new muscle protein. They do this primarily by activating a signalling pathway called mTOR (7).
Research shows that leucine is the most effective BCAA for activating mTOR and boosting MPS (8).
In one study, participants were given leucine, isoleucine or valine during resistance exercise. Leucine was found to increase MPS by 33%, while isoleucine and valine had no significant effect (9).
For this reason, leucine is considered the most important BCAA for muscle growth.
BCAAs may decrease muscle soreness from exercise
Delayed onset muscle soreness (DOMS) refers to the muscle pain and decreased performance that occurs 12–24 hours after exercise.
BCAA supplements may help reduce exercise-induced muscle damage and alleviate DOMS, but findings are mixed.
A study in 20 marathon runners found that BCAAs with glutamine reduced DOMS and muscle damage after the marathon (10).
Similarly, supplementation with 18 grams of BCAAs daily for one week before exercise minimized muscle soreness in healthy, active men. However, markers of muscle damage remained unchanged (11).
Conversely, other studies have shown no effect. Two weeks of BCAA supplementation had no impact on DOMS or muscle damage in resistance-trained men (12).
Overall, while some studies demonstrate a beneficial effect, the evidence is too inconsistent to conclusively state that BCAAs reduce DOMS.
BCAAs may improve mental function during exercise
Mental fatigue can impair exercise performance just as much as physical fatigue (13).
Some research indicates that BCAAs may help prevent mental decline during prolonged exercise (14, 15).
One study had participants perform a cognitive task while running to exhaustion on a treadmill. They were given a drink with either carbohydrates, BCAAs or a placebo.
The BCAA group performed 50% better on the mental challenge after running compared to the placebo and carb groups (14).
In another study, BCAA supplements enhanced attention and alertness in soldiers participating in a 4-day arduous march (15).
The effects of BCAAs on mental function likely occur because BCAAs are transported to the brain, where they serve as precursors for important neurotransmitters (16).
However, the effects of BCAAs on mental function during exercise are not well studied, and benefits are not guaranteed.
BCAAs may reduce fatigue and exertion
Strenuous and prolonged exercise often leads to fatigue and exhaustion. Since BCAAs may counter mental decline during exercise, it’s believed they may also reduce general fatigue.
One study gave participants a drink with either carbohydrates, branched-chain amino acids or a placebo during a cycling exercise test until exhaustion. BCAA supplementation increased exercise time to exhaustion by 12% (17).
In competitive swimmers, four weeks of BCAA supplementation reduced exertion during a swimming exercise test (18).
Fatigue during exercise may also be delayed because BCAAs help remove serotonin from the brain. Serotonin is a brain chemical that increases feelings of fatigue (19).
BCAA supplements likely reduce physical and mental fatigue during exercise. However, more extensive research in this area is needed.
BCAAs enhance muscle recovery after exercise
In addition to their potential anti-fatigue effects during exercise, emerging research suggests BCAAs may enhance recovery after exercise (20).
One study gave basketball players either a BCAA supplement or placebo for two weeks alongside their normal training. The BCAA group reported less soreness and muscle fatigue following exercise (21).
BCAAs may also speed up recovery by reducing protein breakdown after exercise. Protein breakdown releases amino acids into the blood, which can then be re-used to synthesize new proteins, such as those involved in muscle growth and repair (22).
Studies show BCAA supplementation before or after resistance training reduces markers of protein breakdown (23, 24).
Moreover, a recent review of 22 studies found that BCAA supplements may slightly reduce post-exercise muscle soreness when taken for at least two weeks (25).
BCAAs likely aid recovery by inducing protein synthesis and reducing protein breakdown. Over time, this could lead to adaptations like increased muscle mass and strength.
BCAAs may improve liver health
Cirrhosis is a disease characterized by scarring of liver tissue. It’s generally caused by chronic alcohol use.
BCAA supplements are used as a nutritional intervention for liver cirrhosis because they “bypass” the usual metabolic breakdown of amino acids (26).
It’s believed that BCAAs can help treat liver disease by:
- Preventing muscle wasting
- Reducing fatigue and nausea
- Minimizing the risk of hepatic encephalopathy (brain damage due to liver disease)
One analysis looked at 12 studies including a total of 827 participants with cirrhosis. BCAAs improved survival, reduced the incidence of liver cancer and enhanced quality of life (27).
Supplementing with BCAAs may benefit those with liver disease. However, it’s unclear if BCAAs benefit healthy individuals with normal liver function.
BCAAs may decrease blood sugar levels
BCAA supplements may lower blood sugar levels by improving insulin sensitivity and secretion. This has benefits for diabetes management.
Leucine has been shown to stimulate insulin release from the pancreas (28). Isoleucine and valine may also improve insulin sensitivity in muscle by promoting sugar uptake into cells (29).
In a 12-week study, participants with type 2 diabetes who took BCAA supplements had a significant improvement in hemoglobin A1c (HbA1c), a marker of long-term blood sugar control (30).
What’s more, another analysis reported that people with higher BCAA intake from their normal diet were up to 30% less likely to develop type 2 diabetes (31).
However, studies examining the effect of BCAAs on blood sugar have provided mixed results. Further studies are needed to confirm these potential benefits (32).
How much BCAAs do you need?
There’s currently no daily intake recommendation for BCAAs.
Studies use dosages ranging from 2–20 grams per day, which is typically divided into several servings throughout the day (33).
According to surveys, the average daily leucine intake from food sources is around 2–4 grams per day for young adults. Levels are significantly higher for those consuming high-protein diets (34).
Intakes up to 15–20 grams per day are generally considered safe and effective if taken with adequate water.
The optimal dosage depends on many factors, including your health goals, gender, age and diet. It’s best to follow the dosage instructions on the supplement you purchase.
When to take BCAAs
Your timing of BCAA supplements can influence their effectiveness.
Studies indicate that BCAAs are most effective when taken around exercise. This includes before, during or after (35, 36).
For long-duration endurance exercise, BCAAs may be more beneficial when taken during rather than before exercise (37).
To maximize muscle growth and recovery, aim to consume BCAAs before and/or after resistance exercise (38).
BCAA supplements can be taken at other times throughout the day, between meals to help control hunger sensations.
There are no set guidelines for what timepoints are best. Just ensure you’re taking them on a fairly consistent schedule each day.
Are BCAAs safe?
BCAA supplements are safe for almost everyone. Their main side effects are nausea and fatigue, but these can generally be prevented by taking BCAAs with food and starting with a low dose.
BCAAs do not appear to cause harm or adverse effects in healthy people, even with long-term use of up to one year (39, 40).
Those with the genetic disorder maple syrup urine disease should avoid BCAA supplements due to how their bodies metabolize branched-chain amino acids (41).
Additionally, those with cirrhosis or liver disease should only take BCAA supplements under medical supervision (27).
The bottom line
Branched-chain amino acids contain a minimal amount of calories — approximately 4 calories per gram. The small amount of calories they provide is unlikely to significantly impact your total daily calorie intake.
BCAA supplements offer several potential benefits, especially for those performing strenuous exercise. They may improve mental function during exercise, decrease fatigue and enhance exercise performance and recovery.
While most research has used large supplemental doses of BCAAs, even intakes from high-protein foods promote health. However, more research is needed on the potential health benefits for non-exercising individuals.
Overall, BCAA supplements provide calories, but not very many. They appear safe for most people and may provide impressive benefits for those interested in improving exercise performance and recovery.
Frequently Asked Questions
Do BCAAs break a fast?
BCAA supplements are unlikely to break your fast or affect ketosis. Even though they provide calories and stimulate insulin, the amounts are negligible (42).
When should you take BCAAs?
The best time to take BCAAs is around exercise — before, during and after. They may also be taken between meals to help control appetite and hunger.
Can you take too much BCAAs?
Doses up to 15–20 grams per day are generally safe. Larger doses may cause digestive issues like nausea, bloating and diarrhea. Start low at 5 grams and gradually increase to find your optimal dosage.
Do BCAAs build muscle without exercise?
BCAAs alone are unlikely to increase muscle mass. Resistance exercise is the primary driver of muscle growth. BCAAs mainly enhance growth and recovery when paired with a proper exercise regime.
