Whey protein naturally contains branched-chain amino acids (BCAAs), but people also take BCAAs separately to build muscle or, if they eat below maintenance or train fasted, to prevent muscle loss. Since whey protein can serve both purposes, two questions spring to mind:
1. Is one supplement better than the other for either purpose?
2. Are the two supplements redundant or complementary?
We’ll answer both questions in detail, but first, let’s review some background information. All protein, including the protein you eat and the protein in your body, is made from some combination of 20 amino acids. The 11 your body can synthesize are called nonessential amino acids (NEAAs). The 9 your body cannot synthesize, and thus needs to get from food, are called essential amino acids (EAAs).
There are times, however, when specific NEAAs may become essential due to a disease, temporary illness, or some other condition. For example, burn-victim bodies use glutamine faster than they can make it. Such amino acids are called conditionally essential.
Classification of amino acids by essentiality
There are also amino acids, such as β-alanine and taurine, that aren’t used in protein synthesis but still play a role in metabolism.
Muscle building requires that, on average, muscle protein synthesis (MPS) exceed muscle protein breakdown (MPB), resulting in a net accumulation of muscle protein. All 20 amino acids are needed to build muscle tissue, but MPS is stimulated primarily by the EAAs, and among the EAAs by the BCAAs, and among the BCAAs by leucine. (As we saw, whey is high in EAAs, notably leucine.)
Why MPS matters
Muscle protein synthesis (MPS) is the process of building skeletal muscle tissue, whereas muscle protein breakdown (MPB) is the process of breaking down skeletal muscle tissue. MPB is necessary for muscle growth and adaptation, but for your muscle mass to increase, you need your MPS to exceed your MPB (overall, in the long term).
Note that “protein synthesis” refers to the creation of any protein in your body. If your interest lies in muscle growth, you need to focus on MPS and MPB specifically, lest you be misled by changes in whole-body protein synthesis of the liver, kidneys, and gut. In fact, you should focus on MPS.
When you eat, you produce insulin. Insulin plays only a minor role in stimulating MPS, and only a little insulin (≈15 IU/mL) is necessary to suppress MPB. Consequently, MPS and MPB are affected similarly by 25 grams of protein and by a combination of 25 grams of protein and 50 grams of carbs, even though the latter causes a fivefold greater insulin response. Since you need very little protein to reduce MPB, adding more protein only serves to increase MPS. But then, does MPS translate into actual muscle growth?
The first study to investigate this question answered in the negative. The major problem with this study is that it measured MPS only once, for 6 hours, even though bouts of resistance training affect MPS for 1–3 days. More precisely, MPS was measured first at rest then after exercise, but only at the onset of 16 weeks of resistance training. Those MPS measurements (taken on the first day) were later compared to the muscle-gain measurements (taken on the last day).
Two subsequent studies overcame this limitation by analyzing MPS around the clock. They did find a correlation between muscle growth and increases in MPS, but only after 3 weeks, probably because excessive muscle damage in the early stages of lifting overshadowed the correlation. So, yes, long-term increases in MPS lead to muscle growth. Alas, long-term increases in MPS (days to weeks) are difficult to estimate from short-term increases in MPS (minutes to hours).
Can BCAAs alone build muscle?
Anticaking agents are food additives added to powders to prevent clumping (caking). They work either by absorbing moisture or by coating particles to make them water repellent.
Some common anticaking agents include magnesium stearate, silicon dioxide, calcium silicate, tricalcium phosphate, and stearic acid. You may even see powdered rice used. Most anticaking agents are natural products with well-established metabolic fates (meaning that what happens to them after ingestion is well documented). Magnesium stearate, for example, is simply a combination of magnesium (an essential mineral) and stearic acid (a saturated fatty acid). Calcium silicate is a combination of calcium (an essential mineral) and silica (a trace mineral). At food- additive doses, there is no risk of harm.
A study in some anticaking agents (tricalcium phosphate, calcium silicate, calcium stearate, corn starch, and silicon dioxide) found they hasten the degradation of vitamin C powder in high humidity (>75%),166 but vitamin C is known to degrade in the presence of water, whereas protein powders are not.
Technically, no, since your muscles are composed of all 20 amino acids. In practice, BCAAs taken alone can promote muscle growth, if your body can get the 17 other amino acids in some other way (it can synthesize 11 of them; the other 6 it may find in
some food you’re still digesting, for instance). Still, BCAAs or even EAAs taken alone stimulate MPS less than the same amount of BCAAs or EAAs from whey protein.
But isn’t leucine the most anabolic of the amino acids? It is, and yet, taken alone in a fasted state, it increases MPS and anabolic signaling (notably through the mTOR/p70S6K pathway) for about 1.5 hours only. MPS stops as soon as another of the EAAs gets depleted. BCAAs contain only 3 of the 9 EAAs: leucine, isoleucine, and valine.
One study compared 25 grams of whey protein (providing 3 grams of leucine), 6.25 grams of whey protein mixed with leucine (3 grams of leucine in total), and 6.25 grams of whey protein mixed with EAAs (0.75 grams of leucine in total, and as much of the other EAAs as in 25 grams of whey protein). At the 3-hour mark post-fasted-exercise, all three supplements stimulated MPS similarly, but at the 5-hour mark, only the pure whey protein still stimulated MPS. Without the exercise stimulus, however, even the pure whey protein could not increase MPS past the 3-hour mark.
All right. But it isn’t too surprising that, for a same amount of leucine, the pure whey protein (which contains more amino acids total) should win out. What would happen, though, if you increased the dose of added leucine? A follow-up study set to answer that question. It found that, at the 4.5-hour mark post-fasted-exercise, 25 grams of whey protein (providing 3 grams of leucine) and 6.25 grams of whey protein plus 4.25 grams of leucine (5 grams of leucine in total) stimulated MPS similarly, whereas 6.25 grams of whey protein plus 2.25 grams of leucine (3 grams of leucine in total) no longer stimulated MPS.
Interestingly, this same study also found that 6.25 grams of whey protein mixed with BCAAs (5 grams of leucine in total) stimulated MPS less than 6.25 grams of whey protein plus 4.25 grams of leucine (also 5 grams of leucine in total). In other words, leucine stimulated MPS more when not taken alongside the two other BCAAs, possibly because all three BCAAs share intestinal and muscular transporters, so that isoleucine and valine compete with leucine for both absorption in the gut and entry into muscle tissue.
If you don’t get enough protein, you can take small doses of leucine to compensate — to some extent, and only with regard to muscle building. Importantly, BCAAs or EAAs tak- en alone stimulate MPS less than the same amount of BCAAs or EAAs from whey protein, which contains all 20 amino acids.
Can BCAAs alone stop muscle loss?
BCAAs can help slow muscle loss, but they cannot stop or prevent it.
The amino acid pool represents all the amino acids available to your body for protein synthesis and other functions. Whenever your body uses amino acids, it gets them from this pool, which gets replenished by the protein you eat and through breakdown of your body’s own protein.
Your body is constantly breaking down its old and damaged proteins, recycling any amino acids it can, and rebuilding the broken-down proteins if appropriate, in a process called protein turnover.
There are 20 amino acids. Your body can synthesize the 11 NEAAs, but, when you’re in a fasted state, it can only get the EAAs it needs through the breakdown of its own protein. Following an overnight fast, about 85% of the protein your body is ready to sacrifice comes from its skeletal muscle, and MPB is about 30% greater than MPS, your body is releasing EAAs from your skeletal muscle to synthesize the proteins your organs need to keep you alive.
Some MPB is necessary for muscle growth and adaptation. Exercise increases MPS, but also MPB, leaving your body in a catabolic state. After exercise, consuming of all 9 EAAs can ensure that your body won’t need to keep breaking down its own proteins; it will shift into an anabolic state by suppressing MPB and increasing MPS.
However, consuming only some of the EAAs, only the BCAAs, for instance, or only leucine, won’t have the same effect. Following an overnight fast, BCAA infusion suppressed both MPB and MPS in two studies, one lasting 3 hours and the other 16 hours. Because MPB suppression is stronger, overall net protein loss is slightly reduced, but the body remains in a catabolic state throughout.
When you’re in a fasted state, taking BCAAs can only slow muscle loss, whereas taking a protein rich in all the EAAs can stop it.
Do BCAAs benefit body composition?
As we’ve just seen, BCAAs alone cannot promote muscle growth; but what if you add them to your daily food? Leucine especially: since it increases anabolic signaling and MPS, cannot it promote muscle growth if your diet contains the required building blocks?
In healthy, untrained women performing regular resistance-training workouts, taking 10 grams of EAAs (providing 5 grams of BCAAs, including 2 grams of leucine) both before and after a training session, as well as in the morning on non-training days, didn’t alter body composition.
Likewise, in healthy, untrained men performing regular resistance-training workouts, taking 4.5 grams of BCAAs (providing 2.25 grams of leucine) both before and after a training session (four sessions per week) didn’t alter body composition.
On the other hand, during a 21-day trek through the Andes, 5 grams of BCAAs (providing 2.5 grams of leucine) taken thrice daily appeared to preserve muscle mass; but we don’t know how much protein the participants were eating.
Likewise, in resistance-trained men on a hypocaloric high-protein diet (2.7 g/kg/day), taking 7 grams of BCAAs (providing 3.5 grams of leucine) before/during and after a training session was reported to preserve muscle mass. However, other researchers have criticized the study for shady data reporting leading to a flawed conclusion.
Another study in extremely lean (6–8% body fat) elite wrestlers found that BCAAs didn’t help preserve muscle mass but did increase fat loss during a 19-day aggressively hypocaloric diet. However, protein intake was low (1.1 g/kg) and the BCAA dose unrealistic: 0.9 g/kg/day (roughly 67 grams per day, on average, providing some 50 grams of leucine).
In healthy young adults, BCAAs don’t seem to promote muscle growth, but when combined with exercise and a hypocaloric diet, they may help reduce muscle loss or increase fat loss.
Do BCAAs benefit muscular strength, function, or recovery?
Taking 5 grams of BCAAs (providing 2.5 grams of leucine) thrice daily during a 21-day trek through the Andes appeared to preserve both muscle mass and leg strength. Also, although taking 5 grams of leucine twice daily with a meal did not benefit the body composition of older adults undergoing resistance training for 3 months, it did benefit their muscle strength and function (the latter being measured through a standing-balance test, a walking-speed test, etc.).
However, BCAAs didn’t affect muscle strength or function in elite wrestlers or untrained adults. Likewise, adding to meals some 2.5 grams of leucine (alone or with other EAAs) didn’t seem to benefit muscle strength or function in sedentary elderly adults, even when the study included a resistance training program (both the supplement group and the placebo group saw similar improvements from their training).
According to a meta-analysis of eight randomized controlled trials, BCAAs (3–32 g) taken around a training session can reduce perceived muscle soreness the next day. But a different analysis remarked that only low-quality studies found benefits; high-quality studies found none.
BCAAs vs. whey
All of the studies discussed compared BCAAs with nothing or some carbohydrate, rather than with a complete protein. If we are looking for something to add to meals or take after training, we also need to consider protein powders such as whey.
The largest meta-analysis to date has shown that, when combined with resistance training, protein supplementation benefits muscle mass and strength, even in elderly adults, and when only looking at whey protein supplementation. Additionally, a meta-analysis of whey protein studies has shown that taking 25 grams of whey protein before or after exercise reduces muscle soreness and improves recovery for up to 3 days.
The benefits seen from whey protein are both larger and more consistent than the benefits seen from leucine, BCAA, or EAA supplementation. A complete, fast-digesting protein, such as whey, should be your first choice, but if for whatever reason a protein powder is not an option for you, then some isolated leucine, BCAAs, or EAAs may be useful.
Whey protein provides all the benefits of BCAAs and then some.
Hope the above helps you.