Branched-chain amino acids (BCAAs) are a popular supplement taken to boost muscle growth and improve performance during exercise. It comes in either pills or artificially flavored powder form.
BCAAs are a group of three unique essential amino acids: leucine, isoleucine, and valine. These building blocks of protein are the only three that have a chain leading off to one side (hence the name branched-chain).
BCAAs are essential because you cannot manufacture them – you must ingest them – yet they make up a large chunk of the body’s total amino acid pool (up to 40%) (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.
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.
BCAAs may also improve fat loss, boost recovery, fight disease, and improve lifespan.
1BCAAs decrease physical and mental fatigue in women. Research from 1997 (done on humans, not animals) showed that when given BCAAs during exercise, subjects report up to 15% less fatigue compared to a placebo (2).
Another more recent 2011 study, published in the Journal of Sports Medicine and Physical Fitness shows that the BCAA group exercised up to 17% longer than the placebo group (3).
Lastly, research done in 1998 demonstrated that subjects who consumed BCAAs cycled 12% longer compared to the subjects in the placebo group (4).
It must be noted however that the effect of BCAAs on exercise fatigue is much more significant in untrained individuals compared to trained individuals (5).
2BCAAs can reduce muscle soreness and delayed onset muscle soreness in women. BCAAs work to lower blood levels of two enzymes, creatine kinase, and lactate dehydrogenase; which are involved in the muscle damage pathways.
A 2000 study showed that by reducing these enzymes, BCAAs could improve your recovery by protecting against increased muscle damage (6).
A few more studies tested this by putting subjects through a workout and asking them to rate their level of muscle soreness. Placebo groups rated their muscle soreness levels as much as 33% higher compared to those given a BCAA supplement (7, 8, 9).
3BCAAs increase protein synthesis and muscle mass in women. A popular use of BCAA supplementation is to increase muscle mass. This claim is supported by research done in 2006, that illustrates BCAAs do increase enzymes that build lean muscle mass (14).
Specifically, a 1999 study showed that of all the BCAAs, leucine caused the most muscle growth and increase in protein synthesis. Therefore, BCAA products with more leucine resulted in higher levels of overall muscle building (15).
Unfortunately, there is no research supporting that supplementing with BCAAs is more effective than consuming BCAAs from your diet or even from a less expensive protein powder.
4BCAAs help maintain normal blood sugar levels and reduce diabetes prevalence in women. Two studies (2005 and 2006) showed that leucine and isoleucine are the two BCAAs that may increase insulin production to support your muscles by taking in more sugar from your blood to ultimately lower your blood sugar levels (16, 17).
However, a different 2005 study published in the American Journal of Physiology, Endocrinology, and Metabolism demonstrated evidence for these claims to be mixed (18).
Another 2009 study published in Cell Metabolism showed that if you have a high-fat diet, then consuming BCAA supplements can lead to insulin resistance (19).
The good news is that the effect of high-fat diets on BCAA supplement’s effectiveness in the body is tested mainly on animals or cells. Thus, the results may not accurately depict what occurs in the human body as everybody’s biochemistry will ultimately determine the end result.
For instance, one 2012 study showed that 10 liver disease subjects who supplemented with 12.5 grams of BCAAs three times a day that had their blood sugar levels reduced while 17 saw no change (20).
At the end of the day, more research is needed to draw out a definite conclusion.
5BCAAs promote fat loss and even fight off obesity in women. A 2011 study published in the Journal of Nutrition demonstrated that subjects consuming just 12g per day BCAA through their diet had a 30% higher risk of obesity than those who consumed 15g daily from a BCAA supplement (21).
One study on competitive wrestlers saw that consuming a high protein calorie-restricted diet lost 3.5 pounds and 0.6% more body fat when they added in BCAAs over 19-days (22).
More research shows that weightlifters supplementing with 28 grams of whey protein daily lost less body fat over 8 weeks versus those given 14 grams of BCAAs daily. The subjects consuming BCAAs also saw more than 4lbs of muscle mass gained over the control group – which helps burn more fat down the line (23).
This is especially beneficial to women since, more often than not, they lack adequate dietary protein on a daily or weekly basis.
6BCAAs can improve the symptoms of patients with liver failure in women. A common complication from liver failure is hepatic encephalopathy (HE). HE causes confusion, coma, and lack of consciousness.
One 2014 study provides evidence that patients who suffer from liver disease and take BCAA supplements can reduce the severity of their HE (24).
Another 2014 study showed that subjects undergoing liver surgery and had been taking a BCAA supplement decreased the duration of their hospital stay reduced the risk of complications from the surgery, and even improved their liver function (25).
Additionally, BCAA supplements are seen to improve resistance to fatigue which translates to improving weakness, quality of sleep, and even cramps in patients with liver disease (26).
One study also showed a 7% reduction in premature death when BCAAs were supplemented for the treatment of liver cancer (27).
7BCAAs can extend your life in women. In addition to being therapeutic, BCAAs have an anti-aging effect because they increase the formation of new mitochondria. In rodent studies, BCAAs have been found to extend lifespan in the same way caloric restriction does, while simultaneously supporting cardiac health (28).
In a 2011 review on BCAAs and human health, scientists write that BCAAs will help you live longer if you get enough of them. Specifically “behave as evolutionary conserved modulators of lifespan.”
8BCAAs support hormone balance during strenuous exercise in women. BCAAs support hormone balance, which plays a role in an athlete’s ability to respond to extreme training loads.
For example, a 2010 study published in the Journal of Strength and Conditioning Research showed that BCAA supplemented athletes had higher testosterone, lower cortisol, and less inflammation in response to high-intensity training versus the placebo group (29).
A second study (2011) published in the Chinese Journal of Physiology found that trainees had a better hormonal profile, lower cortisol, and higher testosterone after strenuous exercise if they consumed a mixture of carbs, BCAAs, and arginine versus a placebo group. They also recovered more quickly and expressed lower levels of fatigue (30).
9BCAA’s may prevent muscle loss in women during endurance training. In addition to improving endurance performance, BCAAs prevent muscle loss during ultra-endurance exercise. For example, it was found that trained athletes who performed a 24-hour-long exercise trial that included 12 cycles of running, cycling, and kayaking experienced significant muscle protein degradation and had evidence of metabolic stress linked with muscle damage (31).
There was a pronounced drop in plasma levels of BCAAs over the exercise trial, which is linked with muscle loss. Scientists suggest that providing “simultaneous nutritional support” with BCAAs or a high-BCAA containing protein will prevent catabolism by improving the overall energy-burning pool so that amino acids aren’t released from muscle tissue.
10BCAA’s supplementation may prevent heart failure. In a 2015 rat study, BCAA supplementation improved outcomes after induced heart failure (32).
A 2016 human trial demonstrated that BCAA breakdown deficiencies are linked to increased heart disease risk (33).
11BCAA’s may improve breathing. A 1988 study published in Critical Care Medicine showed that BCAA supplementation increases ventilatory response, which allows the body to process and receive oxygen at higher rates. BCAA’s also decreased blood CO2 levels by 9% and increased average oxygen intake (by 19%) and minute ventilation (by 22%) (34).
12BCAA’s may decrease reaction times. A 2011 study involving 10 soccer players, showed a decrease of up to 10% in reaction time when players were given BCAA supplements compared to the controls (35).
13BCAA’s may improve sleep. In a 1991 human study involving 7 patients, BCAA supplementation at night increased rapid eye movement (REM) sleep and decreased end-tidal CO2 levels, which are important for dreaming and respiratory function during sleep (36).
14BCAA’s can support the kidneys.BCAA supplementation may reduce the chances of kidney failure by up to 40% by increasing amino acid levels but not protein intake, which decreases kidney damage (37).
15BCAA’s may reduce perceived pain. Norepinephrine is released in the brain to manage pain. BCAA supplementation in rats increased norepinephrine, thereby, reducing pain (38).
1To date, there are no significant or recurring side effects from the consumption of BCAA powders and capsules.
That being said, BCAAs may only be effective if normal dietary protein is inadequate.
2BCAA supplements are not recommended for those with ALS. Those suffering from ALS should not take BCAAs (43).
Plus, there’s a rare congenital disorder known as maple syrup urine disease where subjects should limit their intake of BCAAs because the body cannot process BCAAs effectively (44).
3BCAA’s can cause brain damage in alcoholics. Dietary use of branched-chain amino acids in alcoholics has been associated with liver disease leading to brain damage (hepatic encephalopathy).
4BCAA’s might affect blood sugar levels and complicate surgery. Branched-chain amino acids might affect blood sugar levels, and this might interfere with blood sugar control during and after surgery. Stop using branched-chain amino acids at least 2 weeks before a scheduled surgery.
5BCAA’s might interfere with sleep. Exercise increases levels of serotonin which is one of the reasons you are tired post workout. Serotonin also happens to be critical for sleep as it helps with melatonin production. One study showed that BCAAs decrease serotonin production by competing with tryptophan, a precursor to serotonin (45).
This leads to the theory that BCAAs may interfere with sleep when taken at night. However, more studies are needed to confirm this.
Consuming at least 9grams of BCAAs per day is considered safe and adequate for women (46).
The best time to take BCAA supplements is before and/or after your workout. Many people who are trying to gain muscle also take them in the morning and before bed.
However, the dosage of BCAAs you take will depend on your goals and body. A report from the World Health Organization in 1985 recommends a daily dose of BCAAs based on mass at 15 mg of BCAA per pound (47).
Remember, patients with ALS or maple syrup urine disease should strictly limit their intake of BCAAs.
Note that BCAAs are found in protein-rich foods so that extra BCAA supplementation is not necessarily needed to reach these amounts. BCAA requirements may be higher in highly active women, making supplementation beneficial.
People who include sufficient protein-rich foods in their diets most likely do not need to take supplements.
Should women take BCAAs before, during or after a workout? Research shows it’s more beneficial to ingest BCAAs just before and sip on them during your workout so that your blood is full of them during your training session. You can still take them after as well, but if you had to pick one or the other, definitely go with before training.
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.
Are BCAAs helpful with weight loss for women? While the main benefit isn’t for weight loss, research shows that BCAAs do indeed provide a good amount of weight loss benefits, especially in women.
Are their side effects for BCAAs? No, to date studies haven’t shown any major side effects from consuming BCAAs. There has been reports of nausea and IBS symptoms, but it’s hard to say for certain that it’s a result of BCAA consumption or something else altogether.
Can BCAA cause hair loss? No, there is no research to show that BCAA’s cause hair loss of any sort.
Will BCAAs make me freakishly big and muscular like a man? No, (some) men are muscular, and all have the potential to be because they have much more of the anabolic hormone testosterone running tough their veins. Even if you worked out every day and 100x your BCAA dose, you would never get even close to the potential that men have.
Are BCAAs safe for the liver? Yes, BCAA’s have never shown any liver toxicity.
Is glutamine a BCAA? No, glutamine is another conditionally essential amino acid that is often added to BCAA formulations to enhance their effectiveness.
Are BCAAs safe for women with diabetes? Yes, BCAAs are safe for women with diabetes. Data suggest that a high intake of BCAAs may be associated with a decrease in the risk of diabetes.
Are BCAAs powder or capsules better? Both are equally effective, and it’s more important to choose the one you will actually use.
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.
Why do BCAA’s give me tingles? It is not the BCAA’s but rather the beta-alanine (a common ingredient in pre-workouts alongside BCAA). It’s temporary and will subside in a few hours.
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.
Do BCAA’s make you sleepy? No, BCAA’s have not been shown to induce fatigue. Rather they have been shown to help fight it off.
Branched-chain amino acid supplements demonstrate a variety of beneficial effects in the body including more muscle mass, enhanced fat loss, and longer life expectancy. Even better is that if your diet is high in protein, you won’t need a BCAA supplement because protein has high amounts already.
However, if you’re a competitive athlete or even just a regular woman who want an edge, adding just 10-20g of BCAAs is a simple, cheap and effective way to do it.