Branched-chain amino acids (BCAA’s) are a common supplement taken to boost muscle growth and improve performance during exercise. BCAA’s are a group of the three different essential amino acids leucine, isoleucine, and valine.
BCAA’s may improve fat loss, boost recovery, and enhance muscle growth.
Specifically, a branched chain amino acid means that these building blocks of protein are the only three that have a chain leading off to one side.
BCAA’s are important because you cannot make them in your body, yet they make up a large chunk of the body’s total amino acid pool. Quantitatively, BCAA’s make up 35–40% of all essential amino acids present in your body- with a significant 14–18% of those amino acids stored in your muscles (1).
Further, BCAA’s are not broken down in the liver, like other unbranched amino acids. Instead, they are mostly broken down in the muscle, which provides evidence that BCAA’s may play a role in energy production during exercise (2).
Based on their role in the muscle tissue, BCAA’s may also play a role in regulating your blood sugar levels by sparing glucose from the liver and the muscles and even increasing sugar uptake in muscle cells to lower your blood sugar when needed (6, 7, 8).
BCAA’s may go further to reduce fatigue by modulating your levels of serotonin in the brain (9).
Specifically, leucine is hypothesized to affect your capacity to build lean muscle tissue (10).
Isoleucine and valine seem more geared towards regulated blood sugar (11).
1BCAA’s show evidence of decreasing both physical and mental fatigue. A human study done in 1997 showed that subjects given BCAA’s during exercise report up to 15% less fatigue compared to a placebo (12).
Another 2011 study published in the Journal of Sports Medicine and Physical Fitness demonstrated that this increase in energy, or resistance to fatigue, led the BCAA group to exercise 17% longer compared to the placebo group (13).
Further research, published in 1998, increased the stress of exercise by having subjects undergo a cycling test under excess heat. Subjects were given either a placebo or a drink containing BCAA’s.
In the BCAA group, subjects cycled 12% longer compared to the subjects in the placebo group (14).
Lastly, research done in 1991 showed that the effect of BCAA’s on exercise fatigue is much more significant in untrained individuals compared to trained individuals (15).
2BCAA’s can reduce muscle soreness after exercise. BCAA’s work to lower blood levels of two enzymes, creatine kinase and lactate dehydrogenase, which are involved in the muscle damage pathways.
A 1991 study published in the Journal of Sports Medicine and Physical Fitness showed that by reducing these enzymes, BCAA’s could improve your recovery by protecting against increased muscle damage (16).
A few other studies (2010, 2012 & 2013) tested this by putting subjects through a workout and asking them to rate their level of muscle soreness.
Another 2016 study published in the Journal of Sports Medicine and Physical Fitness, found that subjects given BCAA’s showed up to a 20% increase in performance in the same strength-training tests a day or two later (20, 21).
However, studies continue to show that while BCAA’s are effective supplements in reducing muscle soreness, the effect seems to depend on your gender, training level and general diet (22, 23).
3BCAA’s may increase muscle mass. A common use of BCAA supplementation is to enhance muscle growth. A 2006 study published in the Journal of Nutrition demonstrated the branched-chain amino acids activate key enzymes (mTOR and p70 S6 kinase) in protein synthesis after physical exercise (24).
Another 1999 study showed that BCAA formulations with higher levels of leucine, compared to isoleucine and valine, can be even more effective at increasing muscle mass (25).
This could indicate that leucine, is the reason muscle mass is increased with supplementation – not BCAA’s. However, more research is needed.
4BCAA’s help maintain normal blood sugar levels. Two 2005 studies showed that leucine and isoleucine may increase insulin production to assist your muscles in dealing with glucose – ultimately lowering your blood sugar levels (26, 27).
Some studies even show that, depending on the type of diet you follow, your blood sugar levels may increase. A 2009 study showed if you have a high-fat diet then consuming BCAA supplements can lead to insulin resistance (30, 31).
The good news is that studies regarding the effect of high-fat diets on BCAA supplement’s effect on the body have been mainly performed on animals or in cells. Thus, the results may not accurately depict what occurs in the human body. In the more complicated arena of the human body, the effects seem to depend on your individual biochemistry.
For instance, one 2012 study on subjects with liver disease showed that with 12.5 grams of BCAA’s three times a day reduced blood sugar levels of 10 subjects. Another 17 saw no effect (32).
5BCAA’s can enhance fat loss. A 2011 study published in the Journal of Nutrition showed that subjects who consumed an average of 15 grams of BCAA’s daily were seen to have 30% lower risk obesity or fat gain compared to those only consuming 12 grams per day through their diet (33).
However, total protein consumption is an essential factor for fat loss. Further BCAA’s may help you lose fat as opposed to total body weight (including lean mass).
On 1997 study published in the International Journal of Sports Medicine, on competitive wrestlers, saw that consuming a high protein, calorie-restricted diet, lost 3.5 pounds when they added in BCAA’s over 19-days (34).
The body fat loss in the BCAA group was also significant, as the BCAA group lost 0.6% more body fat than the control group even though the BCAA group consumed equal calories and less total protein each day.
More research done in 2009 shows that weightlifters supplementing with 14 grams of BCAA’s daily lost 1% more body fat over eight weeks compared to those given 28 grams of whey protein daily. The subjects consuming BCAA’s also saw a 4.4 lb gain in muscle mass over the control group (35).
6BCAA’s can improve the symptoms of patients with liver failure. A common complication from liver failure is hepatic encephalopathy. Hepatic encephalopathy causes confusion, coma, and lack of consciousness.
A 2014 study out of Scotland provides evidence that patients who suffer from liver disease and take BCAA supplements can reduce the severity of their hepatic encephalopathy. In the big picture, BCAA’s did not increase the overall rate of survival from liver failure, and they did not decrease the risk of other complications – such as infection or gastric bleeding (36).
Another 2014 study showed that in subjects having liver surgery taking a BCAA supplement improved their liver function, decreased the duration of their hospital stay, and even reduced the risk of complications from the surgery (37).
A 2011 study showed that BCAA supplements are seen to improve resistance to fatigue which translates into improving weakness, quality of sleep, and even cramps in patients with liver disease (38).
More recently, a 2015 study also showed that for the treatment of liver cancer, BCAA supplements help reduce the amount of water retention in the body leading to a 7% reduction of the risk of premature death (39).
1BCAA supplements are not as beneficial as whole proteins. Taking the whole protein source, as opposed to isolated amino acids, can improve absorption because large doses of individual amino acids can outcompete other amino acids for absorption, resulting in better muscle growth (40).
It seems as if BCAA supplementation may only provide benefits if you’re not consuming adequate protein through your diet.
In addition, other research illustrates that BCAA’s may not enhance muscle growth compared to placebo in those following the same exercise program (44).
3BCAA supplements are not recommended for those with ALS. Those suffering from ALS should not take BCAA’s (45).
Plus, there’s a rare congenital disorder known as maple syrup urine disease (MSUD) where subjects should limit their intake of BCAA’s because the body cannot process BCAA;s effectively (46).
BCAA intakes of 15–35 grams per day are considered safe for most people (47). Remember, patients with ALS or maple syrup urine disease should strictly limit their intake of BCAA’s.
The dosage of BCAA’s you take depends on your goals and body. A report from the World Health Organization in 1985 recommends a daily dose of BCAA’s based on mass at 15 mg of BCAA per pound (48).
More research says that illustrates you may be able to use double that, at 34 mg/kg of body weight per day (49).
Based on the average sizes of men and women this translates into at least 9 grams of BCAA’s for women and 12 grams of BCAA’s for men. Note that BCAA’s are found in protein-rich foods so that supplementation BCAA is not necessary to reach these amounts.
BCAA requirements may be higher in highly active people, making supplementation beneficial.
For athletic populations, doses range between 10-20 grams of BCAA’s per day. Optimally, you can take BCAA before or after your workout. For gaining muscle mass you’ll see best results by taking BCAA supplements while fasting (i.e., before bed or in the morning).
Are BCAA’s good for weight loss? Taking a BCAA supplement between meals and before and after every workout will keep your body in a muscle building and fat burning state – which can aid in weight loss. However, it is not a magic cure-all.
When is the best time to consume BCAA’s? BCAA’s are best taken before and during a workout on an empty stomach.
Is BCAA powder or capsules better? They provide the same functions in the body. As such, it is a personal preference.
Is it safe to take BCAA’s? Yes, toxicity is nearly impossible.
Do BCAA’s interact with any drugs or prescription medications? There are no drug interactions.
Can BCAA’s cause hair loss? No, there is no evidence to support that claim.
How many times should you take BCAA’s per day? There is no upper or lower limit for BCAA’s. Rather you should consume them
Can you take BCAA’s on an empty stomach? Yes, in fact an empty stomach may provide an advantage as absorption will be better. However, some people may report an upset stomach from consuming BCAA’s on an empty stomach. Those people should take it with food.
Do I need BCAA’s for cardio? No you do not need to consume BCAA’s for cardio, however it may be a good insurance policy to help prevent any muscle breakdown or at the very least minimize it. This is especially true when performing fasted cardio.
Is it okay to take BCAA’s on non-training days? Yes, BCAA’s are okay to consume on non-training days. They may even be helpful at expediting recovery on off days.
Is glutamine a BCAA? No, L-glutamine is a conditionally essential amino acid. It is often added to BCAA mixtures as it helps recover from exercise-induced muscle damage.
What are the best food sources for BCAA’s? The best food sources include: meat, fish, poultry, milk, beans, cheese, eggs and various seeds and nuts.
Which is the best BCAA? Out of the three BCAA’s, leucine has been shown to have the most muscle and strength supporting benefits.
Does BCAA raise blood sugar? A lot of low carb, paleo or ketogenic dieters are often concerned that BCAAS may raise blood sugar. No, BCAAS do not raise blood sugar or spike insulin.
Branched-chain amino acid supplements show clear and strong effects in regards to increasing muscle growth and boosting physical performance.
The good news is that you may not need to purchase a separate BCAA supplement because many protein sources today already have significant amounts of BCAA’s in them.
At the end of the day taking a BCAA supplement may not be necessary especially if you’re consuming enough protein from your diet- unless you’re a competitive athlete looking for that added nutritional edge to boost muscle building and your performance.