BCAA AND FASTING | All You Need to Know


Are you doing intermittent fasting?  Do BCAA Break a Fast?

Find all you have to know about BCAA and Fasting in this article:

bcaa and fasting

 If you are fasting I bet that you know all the health benefits that INTERMITTENT FASTING comes with it, like autophagy, generation of testosterone, growth hormone and stem cells, just to mention a few. It’s awesome and obviously we don't want to break a fast taking supplement like BCAA, but BCAA’s are an excellent supplement while fasting right? so the question is: 

Do BCAA Break a Fast?

Well, the short answer is yes, if you take BCAA’s while fasting you will break a fast, why? Because we need to remember that BCAA´s are molecules that makes protein, so it has calories, actually taking just 5 grams of BCAA contains 18 calories, that’s enough to leave your body out of fasting.


5 g

Valor Energético

18 Kcal


0,0 g


0,0 g


4,5 g


nutritional information by @nutrisports

Can I take BCAA while fasting?

Even that we mentioned before, the answer is yes, you could have the benefits from BCAA if you are on an Intermittent Fasting Diet, the secret is just to know when you have to take it, Intermittent fasting isn’t about dont eat at all; is about organize your meal times dividing your calories in a specific way, so you can take BCAA’s while fasting in your expected period of eating time. 


What are BCAA’s?

The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are among the nine essential amino acids for humans and account for ∼35% of the essential amino acids in muscle proteins and ∼40% of the preformed amino acids required by mammals. This kind of amino acids must be consumed externally because the body does not create them by itself, the importance of these three essential amino acids lies in the fact that they are responsible for building one third of the skeletal muscles in the human body. Hence its fame as a supplement to improve muscle mass.

Should I take BCAA while intermittent fasting?

 Take BCAA on an intermittent fasting is not needed but advisable: fasting is  considered as an optimal intervention to improve health and life expectancy, increasing resistance to stress, slow aging and increase longevity without the undesirable side effects associated with alternative interventions. has been shown that one of the most important effects of intermittent fasting is the autophagy stage. The scientific evidence indicates that autophagy is induced in a wide variety of tissues and organs in response to food deprivation and taking bcaa while fasting have a lot of benefits.


bcaa fasting


Do bcaas stop autophagy?

As mentioned earlier, the consumption of BCAA can influence insulin response, which in turn can inhibit both autophagy and the fasting process. In this regard, numerous advocates of fasting training recommend the use of BCAA prior to exercise to assist in muscle preservation and enhance the subsequent anabolic response to training.

What are the benefits of BCAA while fasting?

As we said before, autophagy literally means "self-eating" and is a vital cleanup process for cell regeneration. It eliminates the “dying cells” (which no longer work quite well) and renews them with new cell tissue, so, what do we need for create new cells? exactly, amino acids, BCAA.

Actually Fermo, K.T., da Silva Lemos, I., Farias, H.R. (2023) Demonstrating that the administration of BCAA increases autophagy and autophagic cell death, possibly mediated by the elevated levels of reactive species generated by BCAA

In addition, there are different studies where show the benefits for taking BCAA on an Intermittent Fasting:

  • Branch Out to Work Out Longe
  • Branch Out to Get Bigger and Stronger
  • Branch Out to Delay Fatigue 
  • Branch Out for Fat-Loss 

“Research has shown that the BCAA, particularly leucine, increase muscle growth by directly stimulating muscle protein synthesis. Leucine acts like a key that turns on the process that strings the amino acids together to build muscle protein. Additionally, leucine boosts insulin levels. Insulin is an anabolic hormone that further stimulates protein synthesis.” (Jim Stoppani, Ph.D., 2023)


How much BCAA’s do i have to take when i'm on an Intermittent FASTING?

Every time you take BCAA’s you should consume between 5 and 10 grams. The most critical time to take them is around workouts, so add 5-10 grams to your pre- and post-workout shakes, obviously only if you're in your eating window.

If building mass is your goal, also consider taking a dose of BCAAs upon waking to help stop the muscle breakdown that kicks in during the overnight fast while you sleep. You can also take a 5-10 gram dose of BCAAs at any other time of the day to get a boost of mental energy, reduce hunger, and aid muscle growth. It's all a matter of balancing doses with fasting periods.

Best BCAA's for fasting:

    1. Nutricost BCAA Powder
    2. XTEND Original BCAA
    3. Optimum Nutrition Instantized BCAA


xtend bcaa fasting  
bca autopaghy 


Bibliographic references:

  • Bagherniya M, Butler AE, Barreto GE, Sahebkar A, The effect of fasting or calorie restriction on autophagy induction: a review of the literature, Ageing Research Reviews (2018), https://doi.org/10.1016/j.arr.2018.08.004
  • Fermo, K.T., da Silva Lemos, I., Farias, H.R. et al. Branched-chain amino acids (BCAA) administration increases autophagy and the autophagic pathway in brain tissue of rats submitted to a Maple Syrup Urine Disease (MSUD) protocol. Metab Brain Dis 38, 287–293 (2023). https://doi.org/10.1007/s11011-022-01109-y 
  •  Greer, BK, et al. Branched-chain amino acid supplementation and indicators of muscle damage after endurance exercise.Int J Sport Nutr Exerc Metab. 2007 Dec;17(6):595-607.
  • Yoshiharu Shimomura, Taro Murakami, Naoya Nakai, Masaru Nagasaki, Robert A. Harris, Exercise Promotes BCAA Catabolism: Effects of BCAA Supplementation on Skeletal Muscle during Exercise, The Journal of Nutrition, Volume 134, Issue 6, June 2004, Pages 1583S–1587S, https://doi.org/10.1093/jn/134.6.1583S


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