The BCAA Myth
BCAAs play an important role in muscle growth and retention, but are only 3 of the 9 EAAs the body needs. Consumed alone, they have essentially no effect on muscle synthesis.
What are BCAAs? Why do people take them and where do they fall short when it comes to muscle growth and retention?
- BCAAs are 3 of the 9 essential amino acids; leucine, isoleucine and valine.
- People take BCAAs with the hopes that it will stimulate muscle protein synthesis, help them avoid fatigue and focus better during workouts. It has been a huge player in the supplement industry for the past decade.
- The claims made are based on studies done in rats in the 2006. Since then many studies have been done on humans and have shown that in fact BCAAs taken alone have no effect on muscle growth and retention as compared to a taking a balanced EAA supplement.
- Some of the science that is known about BCAAs is true but like many supplements we need to look further, a layer deeper, into what happens once it enters the body and the interaction with the millions of other chemical reactions happening at any given time.
- When it comes to amino acids, we have to take a balanced approach. Our bodies have many mechanisms in place to make sure that the amino acid ratio in the blood stays constant.
Let’s look more specifically at some of the BCAA myths out there and the real science behind muscle growth.
Myth or Reality: Do BCAAs Really Work?
While BCAAs are vital for energy production and muscle metabolism, BCAAs alone do not stimulate muscle protein synthesis.
Myth 1: Spiking leucine levels will initiate the metabolic processes for protein synthesis and increase protein turnover.
Leucine is particularly popular in the supplement industry because it is known to be a key regulator of the rate of protein synthesis.
It not only gets incorporated into protein itself, but it can activate the molecular processes that are involved in initiating the process of protein synthesis2.
The idea behind BCAAs and leucine supplements is that spiking leucine levels will initiate the metabolic processes for protein synthesis and increase protein turnover.
Let’s look at why this doesn’t work as you might think it would:
- Spiking leucine in the system signals the enzyme that degrades not only leucine but all BCAAs. This happens because the body is trying to keep the overall EAA ratio in the amino acid pool constant. You are left with an imbalance of EAAs.
- The imbalance that is created prevents muscle protein synthesis to be completed as the body needs all EAAs present at the same time in the right concentration, otherwise the translation process is aborted3.
You can think of leucine as a the key to the car, but you still need enough gas to go anywhere.
The best way to stimulate protein synthesis is to take a balanced profile of EAAs that is optimal for protein synthesis, this is the most potent and effective method because it not only starts the process but also gives the body the building blocks it needs to follow through the whole process4.
Other ways to stimulate the body is high quality dietary protein, resistance training, and anabolic hormones like growth hormone and testosterone. These aren’t as effective because you still need to ensure that you have a sufficient amount of amino acids available in the system to complete the protein synthesis process.
Myth 2: BCAAs Help Increase Performance and Reduce Fatigue
When we exercise the oxidation of leucine increases within the body naturally.
The dip in leucine is an issue for a couple reasons:
- There is not enough leucine present in the amino acid pool for muscle protein synthesis to occur, thus limiting the benefits of exercise.
- The dip in leucine increases serotonin production in the brain which impacts mental focus and energy.
BCAA were thought to minimize serotonin activity by boosting the leucine in the body and thus helping with mental focus and performance. Logically this makes sense, but what happens when you spike leucine levels in the blood?
The body has regulatory mechanisms that helps maintain the EAA ratio in the blood (pg27) An enzyme is activated that degrades the amount of leucine, but it also degrades the other BCAAs in the process as well. You’re left with decreased concentrations of all your BCAAs which will limit the rate of protein turnover.
Even if you take a supplement with all three BCAAs, it still offsets the natural ratio of EAAs in the amino acid pool thus BCAAs do not have a demonstrable beneficial effect on protein synthesis5.
Most people take BCAA supplements before and during their workouts when the body is already primed to oxidize BCAAs like leucine so you’re left with no measurable effect6.
To get an increase in protein turnover and get the most benefits out of your workout it is best to supply the body with a balanced ratio of EAAs. The perfect ratio will not disturb the body or signal it to oxidize any of the EAAs. Taking an EAA will also increase the production and functioning of mitochondria.
Aerobic:Take EAA within 1 hr after
Resistance: Take EAA 30min before & Take EAA after
The effect of BCAAs on muscle protein compared to EAAs and whey protein isolate
BCAA-only supplements have no significant influence on muscle protein synthesis.
When taken alone, without the other 6 EAAs, BCAAs actually have an adverse effect on muscle protein synthesis as they throw off the body’s amino acid pool and trigger the degradation of all the BCAAs within the system.
Find out how muscles are formed, the solution to maintaining and gaining quality muscle and how you can achieve your health and wellness goals.
1.Robert Wolfe, Essential Amino Acid Solutions for Everyone (unpublished, 2016), 97.
2.Robert Wolfe, Essential Amino Acid Solutions for Everyone (unpublished, 2016), 27.
3.Robert Wolfe, Essential Amino Acid Solutions for Everyone (unpublished, 2016), 41.
4.Robert Wolfe, Essential Amino Acid Solutions for Everyone (unpublished, 2016), 43.
5.Robert Wolfe, Essential Amino Acid Solutions for Everyone (unpublished, 2016), 27.
6.Robert Wolfe, Essential Amino Acid Solutions for Everyone (unpublished, 2016), 105.