Intermittent fasting has been growing in popularity in recent years as a method for weight loss, improved metabolic health, and even longevity. However, there are concerns among some people that intermittent fasting may negatively affect muscle growth and lead to muscle loss.

In this article, we will explore whether it is possible to build muscle while fasting and examine the science behind intermittent fasting and muscle growth.

What is Intermittent Fasting?

Intermittent fasting is a dietary pattern that involves alternating between periods of fasting and periods of eating. There are several different approaches to intermittent fasting, but the most common are:

• 16/8 method: This involves fasting for 16 hours and then eating during an 8-hour window.

• 5:2 method: This involves eating normally for 5 days of the week and then consuming only 500-600 calories on the other 2 days.

• Alternate day fasting: This involves alternating between a day of normal eating and a day of fasting.

• Eat-stop-eat: This involves fasting for 24 hours once or twice a week.

During the fasting periods, individuals typically consume little or no food, although water, tea, and coffee are usually permitted.

Intermittent Fasting and Muscle Growth

One concern among people who are interested in building muscle is whether intermittent fasting can negatively affect muscle growth. There are several factors to consider when examining the relationship between intermittent fasting and muscle growth.

Protein Intake

Protein is essential for muscle growth, repair, and maintenance. Therefore, it is important for people who want to build muscle to consume an adequate amount of protein.

During intermittent fasting, there is often a shorter window of time for individuals to consume their daily calorie and protein intake. For example, if someone is following the 16/8 method, they will need to consume all of their daily calories and protein within an 8-hour window.

However, studies have shown that intermittent fasting does not necessarily lead to a decrease in protein intake. In fact, some studies have found that people who practice intermittent fasting consume the same amount of protein as those who do not practice intermittent fasting (1).

Additionally, studies have found that consuming protein during the feeding window can help to promote muscle protein synthesis, which is the process by which muscles grow and repair (2). Therefore, as long as individuals consume an adequate amount of protein during the feeding window, intermittent fasting should not negatively affect muscle growth.

Hormonal Response

Hormones play an important role in muscle growth. Specifically, two hormones, insulin and growth hormone, are particularly important for muscle growth.

Insulin is a hormone that is released in response to food intake. It helps to transport glucose into cells for energy and also stimulates muscle protein synthesis. Growth hormone, on the other hand, is released during fasting periods and helps to promote fat burning and muscle growth.

Intermittent fasting can lead to changes in the hormonal response to food intake. Studies have shown that intermittent fasting can increase insulin sensitivity, which means that the body is better able to use insulin to transport glucose into cells (3).

Additionally, intermittent fasting has been shown to increase growth hormone levels (4). This is likely due to the fact that growth hormone is released during fasting periods, and intermittent fasting involves periods of fasting.

Overall, the hormonal response to intermittent fasting may actually promote muscle growth rather than hinder it.

Calorie Intake

Calorie intake is also an important factor to consider when examining the relationship between intermittent fasting and muscle growth. In order to build muscle, individuals need to consume more calories than they burn.

During intermittent fasting, individuals may have a shorter window of time to consume their daily calories. This can make it more challenging to consume enough calories to support muscle growth.

However, studies have shown that intermittent fasting does not necessarily lead to a decrease in overall calorie intake. In fact, some studies have found that people who practice intermittent fasting consume the same amount of calories as those who do not practice intermittent fasting (1).

Additionally, some people find that intermittent fasting actually helps them to control their calorie intake. By limiting the amount of time they have to eat, they are more mindful of their food choices and are less likely to overeat.

Therefore, as long as individuals consume an adequate amount of calories during the feeding window, intermittent fasting should not negatively affect muscle growth.

Exercise

Exercise is another important factor to consider when examining the relationship between intermittent fasting and muscle growth. In order to build muscle, individuals need to engage in regular resistance training exercises.

Studies have shown that resistance training can help to stimulate muscle protein synthesis and promote muscle growth (5). Additionally, combining resistance training with a high-protein diet can lead to even greater muscle gains (6).

Intermittent fasting does not necessarily have a negative effect on exercise performance or muscle growth. In fact, some studies have found that intermittent fasting can actually improve exercise performance (7). This may be due to the fact that fasting has been shown to increase growth hormone levels, which can promote fat burning and muscle growth.

Additionally, some studies have found that combining intermittent fasting with resistance training can lead to improvements in body composition, including increased muscle mass (8). Therefore, as long as individuals engage in regular resistance training exercises, intermittent fasting should not negatively affect muscle growth.

Conclusion

In conclusion, intermittent fasting does not necessarily have a negative effect on muscle growth. As long as individuals consume an adequate amount of protein and calories during the feeding window, engage in regular resistance training exercises, and take other factors into account, such as hydration and electrolyte balance, intermittent fasting can be a safe and effective way to promote muscle growth and improve overall health.

However, it is important to note that intermittent fasting may not be appropriate for everyone. Individuals who have a history of disordered eating, are pregnant or breastfeeding, or have certain medical conditions should consult with their healthcare provider before starting an intermittent fasting regimen.

Overall, intermittent fasting can be a valuable tool for individuals who are looking to improve their health and fitness goals. By combining intermittent fasting with regular exercise and a healthy diet, individuals can achieve their muscle growth goals and improve their overall health and wellbeing.

References:

1. Tinsley, G. M., & La Bounty, P. M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition reviews, 73(10), 661-674.

2. Phillips, S. M. (2012). Nutrient-rich meat proteins in offsetting age-related muscle loss. Meat science, 92(3), 174-178.

3. Halberg, N., Henriksen, M., Söderhamn, N., Stallknecht, B., Ploug, T., Schjerling, P., ... & Dela, F. (2005). Effect of intermittent fasting and refeeding on insulin action in healthy men. Journal of Applied Physiology, 99(6), 2128-2136.

4. Ho, K. Y., Veldhuis, J. D., Johnson, M. L., Furlanetto, R., Evans, W. S., Alberti, K. G., ... & Thorner, M. O. (1988). Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. Journal of Clinical Investigation, 81(4), 968-975.

5. Phillips, S. M. (2014). A brief review of critical processes in exercise-induced muscular hypertrophy. Sports Medicine, 44(Suppl 1), S145-S153.

6. Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., ... & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 52(6), 376-384.

7. Stote, K. S., Baer, D. J., Spears, K., Paul, D. R., Harris, G. K., Rumpler, W. V., ... & Mattson, M. P. (2007). A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. American Journal of Clinical Nutrition, 85(4), 981-988.

8. Varady, K. A., Bhutani, S., Church, E. C., & Klempel, M. C. (2009). Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults. American Journal of Clinical Nutrition, 90(5), 1138-1143.