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Top 3 Benefits of Branched-Chain Amino Acids (BCAAs) for Exercise & Fasting

Aug 18, 2016 | Grant Gill

If you’ve spent much time in a gym you have probably seen a herculean aspirant walking around with a gallon of radioactive looking liquid lifting ridiculous things. 


They are drinking Branched-Chain Amino Acids (BCAAs), and regardless of what your gym or health goals are you should be taking them too - especially if you are fasting. So let’s talk about why.

What are BCAAs?

BCAA is an acronym for Branched-Chain Amino Acids. They are often referred to as the “Building Blocks” of your body, and account for about 35% of your muscle. These amazing little molecules actually kickstart protein synthesis and repair.

Leucine, isoleucine, and valine are the three essential amino acids. Leucine is widely accepted as the most important for muscle growth, but is only effective in the presence of isoleucine and valine. Teamwork!

BCAA Chemical Structure

The essential part is important. Two qualities define a nutrient as essential: it is required for normal health and growth, and it is not manufactured in the body or is not manufactured in sufficient quantities.

Your body cannot produce BCAAs on its own, so you must get them from either food or supplements.

Increasing your BCAA consumption has many benefits, especially if you work out fasted or are fasting for an extended period. In these situations BCAA supplements can come in quite handy.

Here are the top benefits of supplementing with BCAAs with particular attention paid to how they affect your body in the fasted state. 

The Top 3 Benefits of Branched-Chain Amino Acids (BCAAs)

Benefit #1: BCAAs Support Your Immune System

Patients supplementing with BCAAs are less likely to experience complications after surgery. Endurance athletes such as marathoners and triathletes often suffer detrimental effects from immune stress, BCAA supplementation counteracts this.

Fasting Application

Fasting sometimes also causes temporary immune deficiencies. Fasting initiates a process known as fat oxidation, the breakdown of adipose tissue (fat stores) for energy, that releases pollutants stored in the adipose tissue into the body. This process is not dangerous, but can lead to mild sickness sometimes referred to as keto-flu.

BCAAs act as a buffer against released toxins, minimizing the immune stress and making the whole process much more pleasurable.

Benefit #2: BCAAs Enhance Post-Exercise Protein Synthesis

Exercise drains your body’s fuel stores and causes micro-damage to muscle tissue. Protein synthesis is the process of repairing muscular damage, of which BCAAs are foundational. Supplementing with BCAAs facilitates protein synthesis, which speeds up recovery, meaning you grow more muscle.

Fasting Application

Fasting further empties your body of the types of fuel most useful for strenuous exercise, glucose and glycogen stores. Exhausting these energy stores can diminish energy levels, cause difficulty during explosive resistance, and inhibit muscle recovery.

After glycogen stores are depleted your body turns to fat oxidation for energy, BCAAs assist in fat oxidation. BCAA supplementation also enhances muscle recovery by stimulating protein synthesis.

Benefit #3: BCAAs Prevent Muscle Catabolism

Muscle Catabolism is breakdown of muscle fiber. It can occur under a number of circumstances such as during intense exercise, in nutrient deficient environments caused by poor diet, and during rare cases of long-term fasting (mostly people fasting for more than 10 days whose body fat is below 4%).

Multiple studies have demonstrated the ability of BCAA supplementation to prevent muscle catabolism in athletes, elderly persons, and those recovering from major surgery.

Fasting Application

Many researchers, like Jason Fung, have shown that fasting has minimal effect on lean muscle loss. However, some catabolism can occur and no one wants that. BCAAs provide nutrients necessary for muscle preservation in the fasted state.

Summary of the Benefits of BCAA Supplementation

  • Support your immune system.
  • Slow the rate of muscle breakdown.
  • Speed the rate of muscle repair.
  • Boost energy levels during periods of fasting.
  • Increase workout intensity.

Whether you are fasting or just working out like an animal, do your body a favor and get some of this goodness. You can either drink a gallon of green liquid every day, or more conveniently take a few small capsules or tablets. Either way, be sure to get your BCAAs!

Grab them here.



-Garlick, P.J. & Grant, I. (1988). Amino acid infusion increases the sensitivity of muscle protein synthesis in vivo to insulin. Effect of branched -chain amino acids. Biochemistry Journal. V. 254(2).

-Shah, S., Crosslin, D. et al. BCAA Levels are Associated with Improvement in Insulin Resistance with Weight Loss. Diabetologia. February 2012. 55(2), 321-330.

-Bacurau, R.F.P. et al. (2002). Branched-chain amino acid supplementation and the immune response of long distance athletes. Nutrition; Vol 18:Issue 5 (376-379).]

-Carli G, Bonifazi M, Lodi L et al (1992). Changes in exercise-induced hormone response to branched chain amino acid administration. European Journal of Applied Physiology 64, 272-7.

-Coombes J, McNaughton L (1995). The effects of branched chain amino acid supplementation on indicators of muscle damage after prolonged strenuous exercise. Medicine and Science in Sports and Exercise 27, S149 (abstract)

-Kreider RB (1998). Central fatigue hypothesis and overtraining. In Kreider RB, Fry AC, O’Toole M (editors), Overtraining in Sport (pages 309-31). Champaign, Illinois: Human Kinetics

-Gualano, A, et al. Branched-Chain Amino Acids Supplementation Enhances Exercise Capacity and Lipid Oxidation During Endurance Exercise After Muscle Glycogen Depletion. Journal of Sports Medicine and Physical Fitness. 2011.51(5), 82-88.

Grant Gill

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