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5 Effective Tips To Gain Muscle While Intermittent Fasting In 2023

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Medically reviewed by Ramakrishnan, G., Ph.D

intermittent fasting muscle gain

Have you been panting and sweating to shift extra pounds while trying to bulk up? You may have heard that intermittent fasting helps you lose fat, but at the same time, can you lose your newly hard-earned muscle mass as well? 

While intermittent fasting is quickly becoming a health trend with its primary emphasis on weight loss, we ask: can intermittent fasting help you preserve and build muscle? 

Read on to find out different types of intermittent fasting, what happens to your muscles during fasting, and tips for building muscle while on this diet. 

How To Gain Muscle While Intermittent Fasting?

If you want to increase your muscles while fasting intermittently, you might want to combine resistance training, High-Intensity Interval Training (HIIT) sessions, and lifting weights. You may also want to consume foods high in good-quality protein and low in sugar and fat during the window you have for eating.  

Intermittent fasting is a popular choice for losing weight. Research shows that weight loss is typical[1] while you are intermittently fasting, and some studies show you can also maintain or build muscle.[2] If, on the other hand, you want to lose fat without gaining muscle, check out this article.

5 Tips For Muscle Gain While Fasting

Continue To Exercise

If you want to build muscle or preserve muscle, you must continue to train at your full capacity. Depending on which intermittent fasting protocol you are following, you might want to consume a protein snack 1-2 hours before you train and exercise. 

Ideally, you want to consume high-protein foods every few hours for muscle gain, so you should make an effort to cram in enough protein in your eating window. 

Consider Different Types Of Intermittent Fasting

Although intermittent fasting diets vary, most require skipping meals. Here are a few that are popular right now: 

  • The 5:2 Diet: You eat your standard daily calorie intake for five days of the week, then severely restrict your calories to 500-600 calories per day for two non-consecutive days. 
  • The 16/8 Fast: You consume your regular daily calories within 8 hours and fast for the remaining 16 hours of the day. For example, you skip breakfast, eating only between 10.30 am and 6.30 pm. 
  • The Fast 800: You restrict your calories to 800 per day for a fortnight, and you can only consume these within an 8-12 hour time frame each day. 

Consider the different types of intermittent fasting diets and choose one that works for you. You are more likely to succeed if you find one that allows planning your eating period around your work schedule and lifestyle. 

Watch What You Eat

If you want to bulk up or maintain muscle, you will need to consider what you eat carefully. Trying to cram your daily caloric intake into a small window is not an excuse to eat what you want. 

We all know that weight loss occurs by eating fewer calories to create a calorie deficit, but you should actually consume more calories if you want help in building muscles.

However, if you pack in food high in sugar, fat, and empty calories, you will inevitably bulk up – but on fat mass, not muscles. Your high-calorie intake should come from increasing your protein intake[3] with foods, such as baked salmon or chicken breast. 

Preparing and cooking your own meals, and choosing high-quality protein intake is an excellent ways to monitor what you put into your body. Cafeteria food or quick takeaway options are typically jam-packed with the wrong sort of calories. Remember to wash your meals down with water or only zero-calorie beverages. 

Exercise In The Morning

If you want to gain or maintain muscle, you have to find the best time to train. The optimal time for exercise is probably shortly after waking up in the morning or at least four hours before bedtime.[4] 

Studies show that exercising too close to bedtime can affect our levels of deep sleep[4] and REM sleep. So if you want to sleep better, let your body recuperate and support muscle recovery, and do not exercise too close to bedtime. 

You might not want to eat straight after exercising either. Studies also show that waiting a few hours to eat after a workout increases the hormone, human growth hormone (HGH) in our bodies, which helps to burn fat. 

Choose The Right Type Of Exercise

Studies show some exercise types, such as resistance training, make your muscles more sensitive to insulin.[5] Insulin is a hormone that drives glucose into the muscles and is active when glycogen stores are low in the body. 

To help you maintain and build muscle mass, you might want to focus on these types of exercises: 

High-Intensity Interval Training (HIIT)

HIIT is sometimes known as Sprint training or Burst training and involves intense workout sessions followed by 15-30 minutes of rest. 

Studies show that HIIT sessions provide more benefits to health[6] than cardio alone, such as increasing HGH, muscle strength, and muscle stamina, and can improve body composition.

Cardio Training

Cardio is an aerobic exercise and is ideal for losing body fat. Remember that too much cardio and not consuming enough calories may lead to losing lean body mass (including muscles) and fat loss. 

If you need to engage in fat-burning cardio activity yet want new muscle tissue or maintain lean mass, running sprints or exercises incorporating explosive movements with some resistance exercises may help grow muscle. Resistance training[3] also increases muscle protein balance, promoting muscle gain.

Weight Lifting

Lifting weights can indeed help you in building or maintaining muscle, but you need to consider the role of glucose in muscle recovery after a heavy lifting session, particularly during fasting. 

Unlike HITT workouts, major weight-lifting severely stresses your body to warrant an immediate feeding period – but this may not be easy to achieve depending on your eating window.

Suppose you choose to lift weights as the primary form for building your muscles. In that case, you may want to select an intermittent fasting protocol that allows you to weight lift shortly after eating and so enables you to fast for hours after your workout.  

Intermittent Fasting

Intermittent fasting is a broad term that alternates between normal eating and fasting periods. During this type of fasting, a feeding window begins from the last bite you have from a meal to when your next mouthful of food is (including periods of sleep).   

The two more common types of intermittent fasting are:

  • Alternate-day fasting: This involves fasting every other day. Some people will typically eat nothing on a fasting day, while others will have one meal (small-portioned) on their fasting day. 
  • Time-restricted eating: This regime bans all calories to a specified time frame each day, typically from 4 to 16 hours. The 5:2 diet, 16/8 diet, and Fast 800 are types of time-restricted eating.  

You may have also heard of another high-profile weight loss regimen called the ketogenic diet or ‘Keto’. This diet also helps burn fat and reduce insulin resistance but differs in that you consume high-fat but low-carbohydrate foods.  

Benefits Of Intermittent Fasting

This type of fasting provides many health benefits:

  • Aids weight loss: You will typically lose weight due to fewer meals resulting in lower calories. Studies show that intermittent fasting burns belly fat[7] (visceral fat) which helps with fat loss. 
  • Reduces insulin resistance: Studies show that intermittent fasting reduces the risk of type 2 diabetes by lowering insulin resistance[7] and lowering blood sugar levels. 
  • Increases fatty acid production: Intermittent fasting forces your body to burn stored glucose and then body fat for energy. Your body fat releases fatty acids, which convert to ketones for your body to use as energy sources.[11]
  • Improves cardiovascular health: A study shows that intermittent fasting may reduce the risk of cardiovascular disease[12] by improving diabetes and controlling weight. The same study also revealed participants with improved blood pressure.  

Intermittent Fasting And Exercise

Fasting and exercise help with muscle building, and body weight loss, and affect hormones in your body. It increases HGH and makes your cells more sensitive to insulin.

During a fasting period, glucose is depleted from your muscles. So when you exercise, your performance depends on how efficiently your body burns fat for energy (instead of glucose). 

When your muscle cells have improved insulin sensitivity, the pancreas produces less insulin. Lower insulin levels make our bodies more prone to burn fat as fuel[7] and store glucose as muscle glycogen. 

So if you are doing a heavy weight lifting session and do not eat enough calories, your body will use your muscle cells to break down amino acids for fuel instead.

Do You Lose Muscle Mass While Fasting?

It is unclear whether fasting results in muscle loss, as research reveals mixed results. 

Some studies suggest that you can lose small amounts[1] of lean muscle mass overall after several months of fasting intermittently, while others[13] negatively affect muscle mass. 

A study even found that intermittent fasting may be more effective[14] at maintaining lean muscle mass than other diets, although more research is needed. But overall, it seems unlikely that intermittent fasting will cause any more muscle loss than other conventional diet regimes. 

Can You Gain Muscle Mass While Fasting?

The simple answer is yes, but it depends on the timing and content of your meals and the type of exercises you do.

While most studies look into weight loss while fasting intermittently, limited research shows that intermittent fasting combined with regular resistance training results in similar muscle gains and maintenance[2] compared with other diet types. 

However, trying to gain muscle mass while fasting intermittently may be a tricky task. To gain muscle, you need to bulk up on excess calories and a good amount of protein necessary to build muscle tissue.[15] 

Intermittent fasting means you only have a limited time window to cram in all your calories and protein. You need to carefully balance the timing of your meals within your allocated eating window with specific exercises to maximize muscle gain. 

If your pure goal is to gain muscle quickly, you may find more success by selecting a more suitable dieting plan with no emphasis on eating within a specified timeframe. 


  • Intermittent fasting is quickly becoming a health trend to lose weight with the potential to preserve or gain muscle.
  • You need to balance your calorie intake with enough protein foods for maximum muscle gain and continue to engage in exercises that help build muscle, such as resistance exercises.
  • Intermittent fasting can be beneficial for health, such as burning fat, reducing insulin resistance, increasing human growth hormone, and lowering blood pressure. 
  • If you continue to exercise, intermittent fasting will probably help you in maintaining lean mass and preserving muscle.
  • Remember, you can only successfully bulk up if you stick to your intermittent fasting schedule, so choose one that works for you. 

+ 15 sources

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  2. ‌Moro, T., Tinsley, G., Bianco, A., Marcolin, G., Pacelli, Q.F., Battaglia, G., Palma, A., Gentil, P., Neri, M. and Paoli, A. (2016). Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of Translational Medicine, [online] 14(1). Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5064803/
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  4. ‌Saidi, O., Davenne, D., Lehorgne, C. and Duché, P. (2020). Effects of timing of moderate exercise in the evening on sleep and subsequent dietary intake in lean, young, healthy adults: randomized crossover study. European Journal of Applied Physiology, [online] 120(7), pp.1551–1562. Available at: https://pubmed.ncbi.nlm.nih.gov/32372217/
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  6. ‌Kong, Z., Sun, S., Liu, M. and Shi, Q. (2016). Short-Term High-Intensity Interval Training on Body Composition and Blood Glucose in Overweight and Obese Young Women. Journal of Diabetes Research, [online] 2016, pp.1–9. Available at: https://pubmed.ncbi.nlm.nih.gov/27774458/
  7. ‌Barnosky, A.R., Hoddy, K.K., Unterman, T.G. and Varady, K.A. (2014). Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Translational Research, [online] 164(4), pp.302–311. Available at: https://pubmed.ncbi.nlm.nih.gov/24993615/
  8. ‌Hoddy, K.K., Gibbons, C., Kroeger, C.M., Trepanowski, J.F., Barnosky, A., Bhutani, S., Gabel, K., Finlayson, G. and Varady, K.A. (2016). Changes in hunger and fullness in relation to gut peptides before and after 8 weeks of alternate day fasting. Clinical Nutrition, [online] 35(6), pp.1380–1385. Available at: https://pubmed.ncbi.nlm.nih.gov/27062219/
  9. ‌Huang, Z., Huang, L., Waters, M.J. and Chen, C. (2020). Insulin and Growth Hormone Balance: Implications for Obesity. Trends in Endocrinology & Metabolism, [online] 31(9), pp.642–654. Available at: https://pubmed.ncbi.nlm.nih.gov/32416957/
  10. ‌Bagherniya, M., Butler, A.E., Barreto, G.E. and Sahebkar, A. (2018). The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Ageing Research Reviews, [online] 47, pp.183–197. Available at: https://pubmed.ncbi.nlm.nih.gov/30172870/
  11. ‌Calder, P.C. (2015). Functional Roles of Fatty Acids and Their Effects on Human Health. Journal of Parenteral and Enteral Nutrition, [online] 39(1_suppl), pp.18S32S. Available at: https://pubmed.ncbi.nlm.nih.gov/26177664/ [Accessed 31 May 2021].
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Medically reviewed by:

Christina Cheung holds a Master’s of Pharmacy from the University of Bath (UK) and is a freelance writer specializing in medicine and science. With over a decade of experience as a community and hospital pharmacist both in the UK and abroad, she has dealt first-hand with patients facing medical difficulties and decisions. She now writes to promote medical health and wellness to better the community. Christina also has a published science blog with a passion for inspiring and encouraging medicine and science for kids and students. While not writing, she can be found strolling through the country parks with her family and pet dog.

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