EAAs vs BCAAs: Which is the Best Option for You?

UK Fitness Pro
UK Fitness Pro
· 15 min read
An image representing a comparison of EAAs and BCAAs

Amino acids are organic compounds that are often referred to as the building blocks of protein, as they're what proteins are made of. 

There are two main types of amino acids: non-essential amino acids (those the body can make itself) and essential amino acids (those that need to be consumed). Three of the nine essential amino acids (EAAs)—isoleucine, leucine, and valine—are also known as branched-chain amino acids (BCAAs), a name that refers to a part of the molecule that branches off from the rest. 

Here, we take a look at the scientific evidence on whether BCAA supplements and EAA supplements can promote muscle gain, lean muscle mass, muscle recovery, athletic performance, and other fitness-related goals.

Muscle Growth

Resistance training causes micro-tears in muscle fibres and leads to muscle protein breakdown. 

To repair this damage and strengthen the muscles, the body initiates muscle protein synthesis (MPS). This refers to the incorporation of free amino acids (i.e., those not in proteins) into muscle cells so that fibres can be repaired and muscle tissue can grow. 

Therefore, amino acids play a critical role in muscle building. 


A study featured in the Journal of the International Society of Sports Nutrition (1) highlighted the positive effects of BCAA supplementation on body composition changes in 36 strength-trained men. The participants completed a resistance training routine and were organised into three groups, each receiving different supplements: 14 grams of BCAAs, 28 grams of whey protein, or 28 grams of carbohydrates from a sports drink. The group taking BCAAs experienced significant improvements in lean mass and strength and outperformed the others in terms of skeletal muscle development, body weight increase, and body fat reduction.

An image representing how BCAAs can help with muscle growth

Popular BCAA powders include:

  • Essential BCAA 2:1:1 Powder (average rating: 4.18/5) – a powder providing leucine, isoleucine, and valine in a 2:1:1 ratio, available in various flavours
  • Essential BCAA 4:1:1 Powder (average rating: 4.29/5) – as above, but with a 4:1:1 ratio
  • Vegan BCAA Powder (average rating: 4.36/5) – a vegan powder providing leucine, isoleucine, and valine in a 2:1:1:ratio, available in "unflavoured"
  • Vegan BCAA Sustain Sample (average rating: 4.6/5) – a small and very inexpensive sample providing leucine, isoleucine, and valine in a 2:1:1 ratio, available in various flavours

You can also find a wide range of BCAA and EAA supplements on the Bodybuilding Warehouse website


In a study to assess the effects of EAA supplementation during the initial phase of a heavy-load training programme, 29 young male participants were divided into a placebo group and an EAA-supplemented group for 12 weeks of training (2). The 15-gram EEA supplement consisted of 11% of histidine, 10% of isoleucine, 19% of leucine, 15% of lysine, 3% of methionine, 15% of phenylalanine, 15% of threonine, and 12% of valine. Both groups saw significant increases in muscle mass and strength, though the EAA group experienced more pronounced improvements. 

Popular EAA powders include:

  • Impact EAA (average rating: 4.17/5) – a powder providing all essential amino acids (including lots of leucine), available in two flavours
  • The EAA (average rating; 4.14/5) – a powder providing all essential amino acids (including lots of leucine) and with additional vitamins and minerals, available in four flavours
  • The EAA Sample (average rating; 3/5)– as above, but a small and very inexpensive sample
  • My Vegan EAA (average rating: 4.17/5) – a vegan powder providing all essential amino acids (including lots of leucine), available in a couple of flavours

Lean Muscle Mass


In a study investigating the impact of BCAA supplementation combined with heavy resistance training and a caloric-restricted diet on body composition, 17 resistance-trained males were assigned to either a BCAA (14 grams per day) or carbohydrate (CHO) supplement group for 8 weeks (3). The BCAA group successfully maintained their lean mass and experienced fat loss, contrasting with the CHO group, which lost both lean and body mass. This indicates that BCAA supplementation can help prevent muscle loss in individuals undergoing weight loss with resistance training.

An image representing how BCAAs can help with lean muscle mass

If you're not keen on taking supplements in powder form, Myprotein also has:

  • BCAA Energy Drinks (average rating: 4.39/5) – zero-calorie drinks providing leucine, isoleucine, and valine in a 2:1:1 ratio as well as a range of vitamins, available in various flavours
  • Essential BCAA Tablets (average rating: 4.5/5) – tablets providing leucine, isoleucine, and valine in a 2:1:1 ratio and with added vitamin B6


Researchers at the University of Texas (4) explored the impact of chronic EAA supplementation on muscle health in older women, focusing on muscle protein synthesis and lean body mass (LBM). This double-blind, placebo-controlled trial involved older women who received either a placebo or 15 grams of EAA daily for three months. The results showed that EAA supplementation acutely stimulated muscle protein synthesis initially and led to an increase in LBM and basal muscle protein synthesis over three months. 

Muscle Recovery


In a placebo-controlled investigation, the impact of BCAAs on muscle recovery among resistance-trained athletes was examined (5). 

The athletes received BCAAs at a dosage of 0.087 g/kg of body weight (e.g., about 7.4 grams for an 85-kilo person), with leucine, isoleucine, and valine in a 2:1:1 ratio. The study's exercise regimen included performing 6 sets of 10 full squats at 70% of their one-repetition maximum (1RM). 

A BCAA supplement

The author's bag of BCAAs from Myprotein

The findings indicated that immediate BCAA supplementation significantly improved recovery in terms of muscle strength, counter-movement jump height, and the alleviation of perceived delayed onset muscle soreness (DOMS), especially 24 and 48 hours after exercising.


A study published in the Journal of Physical Therapy Science investigated if a leucine-enriched essential amino acid mixture (LEAA) could mitigate muscle damage and support recovery by enhancing protein synthesis in muscles (6). 

In a double-blind, randomized crossover trial involving ten untrained males, participants performed elbow flexion and extension exercises and consumed either LEAA supplements or a placebo three times daily for a week. The 3.6-gram LEAA supplement contained all nine essential amino acids (leucine, 1.44 g; lysine, 0.6 g; valine, 0.4 g; isoleucine, 0.39 g; threonine, 0.34 g; phenylalanine, 0.24 g; methionine, 0.12 g; histidine, 0.06 g; and tryptophan, 0.03 g). 

The results indicated that LEAA intake significantly reduced the rise in serum creatine phosphokinase (CPK) activity, a marker of muscle damage, suggesting that LEAA can help attenuate muscle damage and facilitate recovery after exercise.

Muscle Soreness


In Japan, a study involving 12 untrained women investigated the impact of BCAA supplementation on muscle soreness and recovery post-exercise (7). 

Participants consumed BCAAs or a placebo prior to engaging in squat exercises, with the study measuring DOMS, muscle force during contractions, and several blood indicators of muscle injury. The findings revealed that those who took BCAAs experienced notably less muscle soreness and a smaller decline in muscle force than those who took the placebo. 

Moreover, BCAA supplementation was effective in preventing the rise in blood markers indicative of muscle damage that is typically seen after exercising. 

An image representing how BCAAs can help with muscle soreness

In line with these findings, a systematic review and meta-analysis featured in Sports Sciences for Health indicates that consuming BCAA powder reduces post-exercise levels of creatine kinase, a biomarker indicative of skeletal muscle breakdown and damage (8).


One study evaluated the effects of EAA supplementation combined with a mix of resistance and aerobic exercises on strength, endurance, flexibility, and recovery, particularly focusing on DOMS (9). Twenty-four participants were divided into two groups to complete a three-day exercise routine, with one group receiving EAA supplements (6.6g daily) mixed with Gatorade and the other receiving just Gatorade, in a double-blind setup. The results showed that the EAA group experienced improvements in flexibility, strength, and endurance exercises such as push-ups and dips, and maintained or improved their performance in sprints and runs, suggesting that EAA supplementation can enhance athletic performance and mitigate DOMS symptoms in individuals starting a new exercise regime.

Athletic Performance


An article in Amino Acids detailed a study where trained cyclists were either given a BCAA supplement or a placebo to consume over a period of 10 weeks, at a dosage of 12 grams daily (10). The study utilised the Wingate test to evaluate anaerobic power, requiring participants to pedal at maximum effort for 30 seconds on a cycling ergometer both before and after the supplementation period. Unlike the placebo group, which saw no significant changes, those who took BCAAs demonstrated a 4% rise in average power output and an impressive 20% surge in peak power output.

An image representing how BCAAs can assist with athletic performance

A study conducted by researchers from the University of Nebraska explored the impact of BCAAs on exercise-induced fatigue in untrained women (11).

The study included 21 participants who were randomly divided into a placebo group and a BCAA group. During a six-week period that combined aerobic and heavy-resistance exercise, the BCAA group consumed an average daily dose of 18.3 grams of BCAAs in pill form. 

The results showed a notable increase in treadmill endurance time for the EAA group, indicating improved aerobic muscle endurance.

There's also evidence that BCAA supplementation can benefit swimmers, tennis players, football players, and other athletes


In a study exploring the effects of EAA and caffeine supplementation on central nervous system (CNS) fatigue and athletic performance, male team sport athletes underwent a repeat sprint running protocol in a hot, hypoxic environment (12). Participants received caffeine (3 mg.kg^-1 body mass) + placebo, EAA (2 × 7 g) + placebo, or caffeine + EAA, before each exercise session. The combination of caffeine and EAA enhanced sprinting and reduced decline in electromyography (EMG) activity (reflecting how well muscles respond to nerves), indicating that caffeine and EAA can improve running performance and attenuate CNS fatigue in challenging conditions.

Energy Levels


A study published in the Journal of Human Kinetics found that consuming 20 grams of BCAAs an hour before an incremental exercise protocol extended the time to exhaustion during exercise in long-distance runners compared to a placebo (13). This may be because serotonin levels in the brain are associated with fatigue, and BCAAs compete with tryptophan, a precursor of serotonin, to enter the brain. The result may also partially reflect the use of BCAAs as an energy source by skeletal muscles.

An image representing how BCAAs can assist with energy levels


A study published in Frontiers in Physiology found that a single dose of EAA-enriched mixture prevented the loss of maximal voluntary contraction (MVC) force observed in the placebo group, indicating a protective effect against muscle fatigue (14). This may reflect how EAAs can stimulate pathways involved in muscle metabolism, including the activation of enzymes involved in energy production.

Overall Health

  • BCAA supplementation has been linked to improved immune system function following intense workouts (15)
  • Evidence from rodents suggests that the BCAA isoleucine could help maintain steady blood sugar levels (16)
  • BCAA supplementation may contribute to digestive system function by promoting intestinal development, enhancing nutrient absorption, and fostering beneficial gut bacteria, thereby maintaining intestinal barrier function and potentially preventing gastrointestinal diseases (17).

EAA and BCAA Supplementation vs. Protein Powders

Just as BCAAs are a subset of EAAs, EAAs are a subset of the amino acids that can be used to make proteins in the human body. 

Therefore, if you consume a complete protein source, such as whey protein powder, you're also consuming all of the EAAs and, therefore, BCAAs. However, each protein supplement and amino acid supplement has different amino acids in different proportions. 

The author's whey protein powder from Myprotein

For example, as there's extensive evidence linking leucine to increased endurance, power, and muscle protein synthesis (18, 19), BCAA supplements tend to come in ratios of leucine to isoleucine to valine of  2:1:1 or 4:1:1. 

An advantage of EAA and BCAA powders is that they are easily dissolved in water and can be sipped on during workouts, whereas whey shakes, being milk-based, aren't ideal for this type of gradual consumption. However, a benefit of whey shakes is that they also contain non-essential amino acids, like arginine, cysteine, glutamic acid, serine, and tyrosine, which have been linked to improved aerobic and anaerobic performance (20), reduced muscle damage (21), and reduced fatigue during exercise (21). Additionally, whey proteins appear to activate peptide hormones that promote feelings of fullness, which may benefit those who want to lose weight (23).  

How Much Protein Do You Need?

The Mayo Clinic recommends that those engaged in resistance training should aim for 1.2–1.7 grams of protein per kilo of body weight per day (e.g., up to 145 grams for an 85-kilo person) to ensure they have enough protein to benefit from their workouts. 

A bowl of eggs and bowls of whey protein powder

While whey protein is an excellent way of increasing your protein intake, you should also aim to eat protein-rich meals based on real foods. For instance, as discussed in our article comparing eggs and whey protein, eggs are a near-perfect source of dietary protein. In terms of their amino acid profiles and digestibility, other high-quality protein sources include casein and pork (24). Reflecting how whey and casein proteins are derived from milk and have excellent amino acid profiles, dairy products can provide complete proteins and, therefore, are sources of EAAs and BCAAs. 

Plant-based food sources of high-quality proteins include peas and soybeans (24). 

The Best Time to Take Supplements

A study published in The Journal of Sports Medicine and Physical Fitness evaluated the efficacy of BCAA supplementation on DOMS and exercise-induced muscle damage (EIMD) when taken before versus after exercise. The results showed that BCAA supplementation before exercise was more effective in reducing DOMS and EIMD compared to taking BCAA after exercise (25). However, another study found that the extent to which BCAA supplementation reduced body fat and increased leg press strength was not significantly influenced by the time of consumption (26). 


Thus, the main difference between EAA vs BCAA supplements is that the former contain all nine essential amino acids while the latter only contain leucine, isoleucine, and valine. 

Although there are likely benefits to EAA supplements having additional amino acids (e.g., tryptophan has been linked to increased power; 27), there may also be benefits related to building muscle and muscle repair associated with the high leucine levels in BCAA supplements (19). Therefore, if you're mainly interested in increasing muscle protein synthesis and your catabolic rate, a BCAA supplement with a lot of leucine might be the better option for you, whereas if you're interested in the benefits offered by EEAs other than the BCAAs, a supplement with all EAAs would be your best option. 

As discussed, there's evidence that EAA and BCAA supplements can support a range of fitness goals, including in relation to lean muscle mass and weight management (3, 4), muscle tissue repair (5, 6), and athletic performance (10–12). Additionally, as amino acids can act as a source of energy, they can reduce fatigue during exercise (13), which is likely also due to other physiological processes (e.g., competition between BCAAs and tryptophan for entry into the brain). Moreover, these supplements may have additional benefits beyond those related to strength and fitness, such as improved immune function (15), more stable blood sugar (16), and enhanced gut health (17). 

You might also like the following articles on BCAAS:

About the Author

Dave Robinson, a co-founder of ukfitness.pro, has a background in psychology (BSc) and neuroscience (MSc, PhD). As well as strength training, he enjoys endurance challenges and has run ultramarathons, cycled across several countries, and completed the Three Peaks Challenge. When writing, he draws on scientific evidence to understand the pros and cons of different diets, supplements, and training regimes. 

The author riding a bike


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27. Javierre, C., Segura, R., Ventura, J. L., Suárez, A., & Rosés, J. M. (2010). L-tryptophan supplementation can decrease fatigue perception during an aerobic exercise with supramaximal intercalated anaerobic bouts in young healthy men. The International journal of neuroscience, 120(5), 319–327. https://doi.org/10.3109/00207450903389404