Best way to tell a great nutritionist from average is their advice on BCAAs. A few years ago the research lead us to believe that BCAAs would help with building and retaining muscle mass. We thought that the additional leucine would work like whole protein but now we know it doesn’t. And we know that in most cases taking BCAAs is a waste of your money. Science is always evolving which means we have to look at the most recent studies. If you look at research from 2000-2016 you may think BCAAs help. But more advanced research over the past 3 years has shown us a more clearer picture.

A well educated nutritionist will be up to date on the latest research and be able to explain that to you. An average nutritionist reads what they see online and repeats that to you.

What are BCAAs?

Branch chain amino acids that are made up of Valine, Leucine and Isoleucine. They are 35% of the essential amino acids found in muscle proteins and account for 40% of the total amino acids required by your body.

What makes them so special?

They are needed to start Muscle Protein Synthesis which is how we build muscle!

We also need all 20 amino acids (that is considered a complete protein) to build muscle we can’t do it with BCAAs alone which means just taking BCAAs won’t help you build muscle.

Studies show that when comparing BCAAs alone to Whey protein the BCAAs alone don’t do the job but they Whey does!

Here’s where people get confused: the dosage is KEY! You need about 2.5-3g of leucine to start MPS. Think of leucine as the key to start the car. You have the engine and the gas but without the key you can’t get the car started. Leucine is the key that starts building muscle along with the other amino acids that make a complete protein.

PMID: 22451437

Which means BCAAs alone or incomplete protein (usually plant based) or a small dose of complete protein without 2.5 grams of leucine will not start muscle protein synthesis.

A quick review of complete proteins: Anything animal based such as meat, dairy, fish and soy. Theres a few plant based complete proteins (quinoa, amaranth, buckwheat) however you need tons of them to get in that 2.5 grams of leucine.

Incomplete proteins (do not have all 20 amino acids) are plant based sources of protein such as wheat, legumes (beans and peanuts), nuts, rice, etc.

I am not turning this post into an animal vs plant based debate I just want to inform you of when you need to take BCAAs.

When do you need BCAAs?

  1. You eat a vegan diet
  • vegan diets make it really hard to balance macros and get the 2.5 g or leucine needed for MPS. You can add to the leucine by supplementing with BCAAs.
  1. You are eating small portions of protein (under 25g protein per serving)
  • this usually applies to women who have smaller portions of protein at each meal. Women who are only eating 120 or less grams per day have trouble hitting 25g protein in each meal. If your meals are 15-20g protein supplementing with BCAAs would be ideal.
  1. You are exercising fasted (which you shouldn’t be doing anyway)
  • if you insist on training fasted or you are an endurance athlete who is fasted for metabolic flexibility I suggest taking BCAAs prior to training to at least preserve the muscle you do have. Keeping your body in a positive amino acid balance will help better than using your muscle for fuel. That’s not good either. If you lift fasted you have more to explore than just this post. You are literally working against yourself in building muscle.
  1. You are a high level athlete who trains for extended periods of time and can’t access whole food or complete protein during your workouts.
  • Exercise causes muscle protein breakdown (MPB). Because your muscles will use amino acids for fuel we will start to deplete our amino acids levels and studies show that replacing them with BCAAs is better than nothing. Ideally a whey protein or “Sport” version of a plant based protein would be best however it’s easier stomach BCAAs during a workout.
  • An interesting hypothesis behind athletic performance and BCAA supplementation is that because BCAAs compete with absorption of tryptophan into the cell, they can cause less serotonin to be released delaying CNS fatigue and allowing for longer aerobic activity. This has not yet been tested but you also hear about diets high in protein causing depression due to. the high level of BCAA competing with the smaller molecule tryptophan. PMID: 16424144
  • There is also hypothesized or theoretical ideas that BCAAs can help minimize protein breakdown and thereby lead to greater muscle gain. But similar to the other research there’s conflicting evidence and more research is needed to come to a solid conclusion.
  • And theres one study which shows an increased supply of BCAA has a sparing effect on muscle glycogen degradation during exercise. But that’s one study on 7 endurance athletes. PMID: 8878139
  1. You are post surgery, injury or other illness that may compromise your amino acid metabolism.

trauma causes your body to metabolize amino acids differently than if you were healthy.

When you don’t need BCAAs

  1. You eat an animal or complete protein plant based diet with at least 1.7g/kg bw (thats about 75% of your total body weight) of protein daily and have meals with protein throughout the day.
  • When taken with a diet that has at least 1.2 g/kg bw protein daily changes in muscle performance or breakdown aren’t significant. PMID: 30275356
  1. You are not an elite level athlete training extended periods of time throughout the day.

The overall conclusion is that there is not enough evidence to say that BCAAs help with glycogen replacement, muscle breakdown, inflammation, recovery or time to exhaustion but their is evidence to show that the addition of leucine to small doses or incomplete protein can help facilitate muscle protein synthesis.