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Intermittent fasting and muscle gain

Intermittent fasting and muscle gain may sound counterproductive. In fact, it is possible to use IF to encourage muscle development.
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Summary
Written by
Dr. Sara Diana Garduno Diaz
PhD & Senior Nutrition Consultant

What we thought we knew about Intermittent Fasting and body composition


For those looking to gain muscle, intermittent fasting may sound counterproductive.

Traditionally, it was thought that in order to support muscle mass development a constant supply of food, in the form of mini meals, was necessary. In combination, it is also generally believed that severe caloric restriction leads the body to enter a „starvation mode “, storing fat preventively in response to starvation.

More recent research contradicts these two stands and goes a step further in suggesting that intermittent fasting (IF) not only prevents fat gain but may also support muscular development when carried out in an informed and planned manner. 


Now we know better 


Scientists have suggested that IF does not trigger the storage of fats. Rather, IF allows the body to use up fat storage as a source of available energy. This process of using fat for fuel may also cause body cells to adapt and become more resilient in a manner that may favor health and increase longevity. 

Contrary to what is popularly accepted, IF does not cause muscle to break down. Although the body can break down protein for fuel when needed (for example, when fasting), it does not target muscular protein. Rather, if required (and only after having depleted stored fats), the body opts for defective protein that may be taken from the skin or intestinal mucosa.

This process is set up to ensure a constant supply of amino acids, the building blocks of protein. We can think of this process as the recycling system of the body. After approximately 14 hours of fasting, this system kicks in as a form of detoxifying and repairing the body. Most of the metabolic routes of the body are designed to preserve muscle mass at all costs, so losing all those gains you’ve worked for should not be your main concern. 


Energy sources during IF


During IF the body prioritizes stored carbs as its first source of energy. These are preferred because they are more readily accessible and can be easily mobilized and broken down as needed. Once these carbohydrates (in the form of glycogen) are depleted, the body moves on to stored fat for its energy source. During this process, counter regulatory hormones are secreted by the body in order to protect lean muscle mass during the fasting period. 

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The importance of human growth hormone


One of the main hormones secreted during IF to protect muscle mass is the human growth hormone (HGH). During fasting, the release of HGH peaks to ensure no muscle mass is compromised. For this reason, fasting is one of the most effective ways to stimulate HGH naturally.

It is important to remember that the natural production of HGH decreases with age, hence IF becomes a way to possibly prolong this process. Since the process of IF creates HGH spikes it is an excellent aid in muscle mass development. 

How to gain muscle while intermittent fasting


It is possible to use the practice of IF to encourage muscular development. To begin with, it is important to remember that IF is not about how much we eat, but rather about when we eat and when we do not. IF does not require caloric reduction. It simply involves timing the intake of calories (energy) to favor fat loss and stimulate muscle gain via hormonal regulation.

Thus, the belief that you will be starving your body of energy while IF is simply not true, as you will still be covering all your energy and nutrient needs daily, as long as you have a well designed IF plan. 


As it was discussed before, IF helps mobilize and use up stored fat in the body. When released, fatty acids from the body are partially converted into ketones, pushing the body to enter a state of ketosis, an additional fat-burning muscle-sparing state. This process is optimized when IF is carried out in combination with a low carbohydrate eating plan. 


Regardless of all the mentioned advantages of IF for muscle development, it is not a magical solution. Training the body is also required for muscle buildup. While IF does not need to compromise regular training, it is important to ensure safe practices before, during and after a workout.

Ensuring a nutrient-dense and energy-sufficient eating plan during the eating period of IF is key for optimal results and to maintain health. While covering daily nutrient and energy requirements while IF can be tricky, it is not impossible. Modifications to the eating window or implementing alternate day fasting models may help tailor an IF practice that makes it possible to achieve these daily food requirements. 


In a world full of quick fixes, more mindful practices such as IF are proving to be a feasible option for a sustainable way of life, both for the optimization of weight loss and for the support of muscle mass development. 

References:

Jiao J, Demontis F. Skeletal muscle autophagy and its role in sarcopenia and organismal aging. Curr Opin Pharmacol. 2017 Jun;34:1-6. doi: 10.1016/j.coph.2017.03.009. Epub 2017 Apr 10. Review. PubMed PMID: 28407519.


Ho KY, Veldhuis JD, Johnson ML, Furlanetto R, Evans WS, Alberti KG, Thorner MO. Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. J Clin Invest. 1988 Apr;81(4):968-75. doi: 10.1172/JCI113450. PubMed PMID: 3127426; PubMed Central PMCID: PMC329619.


Drenick Ej, Swendseid Me, Blahd Wh, Tuttle Sg. Prolonged Starvation As Treatment For Severe Obesity. JAMA. 1964 Jan 11;187:100-5. doi: 10.1001/jama.1964.03060150024006. PubMed PMID: 14066725.


Paoli A, Bosco G, Camporesi EM, Mangar D. Ketosis, ketogenic diet and food intake control: a complex relationship. Front Psychol. 2015;6:27. doi: 10.3389/fpsyg.2015.00027. eCollection 2015. Review. PubMed PMID: 25698989; PubMed Central PMCID: PMC4313585.


Murray B, Rosenbloom C. Fundamentals of glycogen metabolism for coaches and athletes. Nutr Rev. 2018 Apr 1;76(4):243-259. doi: 10.1093/nutrit/nuy001. Review. PubMed PMID: 29444266; PubMed Central PMCID: PMC6019055.



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