Intermittent Fasting Bodybuilding: How to Build Muscle and Stay Lean?

Medically Reviewed by Ana Reisdorf MS, RD on January 22, 2020.

Can you fast and build muscle? Is fasting bad for muscle growth? Can you fast while bodybuilding? These are some common questions people ask about the effects of fasting, notably, intermittent fasting, on muscle growth. 

Also Read: What Can You Drink During Intermittent Fasting?

The bodybuilding world is deeply obsessed with the idea of eating frequent high-protein meals. Many bodybuilders believe such an eating pattern will rev up their metabolism, feed their muscles, and help them gain muscle mass. 

While it might be true in most cases, this is essentially not the gold standard of building muscle and losing weight. 

This article takes a closer look at the common myths about intermittent fasting bodybuilding, the effects of intermittent fasting on muscle mass, and tips to build muscle while fasting. 

A Quick Overview of Intermittent Fasting and Its Health Benefits

Intermittent fasting (IF) is an eating pattern in which you have alternate feeding and fasting periods. 

A slew of studies shows that eating only during certain periods of the day has numerous benefits. 

For example, healthy weight loss, slowed aging process, improved brain health, reduced inflammation, and a lower risk of chronic diseases. 

Moreover, a growing body of evidence suggests that IF could also benefit your gut health and reduce oxidative stress

Related: 8 Benefits That’ll Make You Fall In Love With Intermittent Fasting 

3 Common Intermittent Fasting Bodybuilding Myths Debunked

Myth1: Intermittent Fasting is Equivalent to Starvation. 

Fasting is not starving. While eating nothing for sixteen hours may seem like a herculean task for you, it definitely won’t put you in starvation mode. 

Let’s understand the science behind starvation. 

A healthy 70-kg male usually has 161,000 kcal in his fuel reserve. If he spends 1600 kcal to 6000 kcal per day, the stored calories are enough to fuel his body for the next one to three months. Can a 16-hour fast starve you? No. 

During intermittent fasting, your body turns to stored glycogen and fat cells for energy. Such a shift in metabolism helps to burn fat and lose weight. However, it has nothing to do with muscle loss as muscle proteins are not the primary source of energy for the body. 

Myth 2: Intermittent Fasting Promotes Binge Eating and Blunts Exercise Benefit

It seems quite natural to devour your food following hours of fasting. However, fasters report to eventually be feeling less hungry than when eating often and in small amounts.

Also, the stomach shrinks a bit after not eating for longer periods of time, making it harder to overeat after your fasting window.

Myth 3: Intermittent Fasting Causes Muscle Loss

Intermittent fasting does not cause muscle loss rather it may increase muscle strength. 

Many people think hours of going without food causes the breakdown of muscle proteins. 

However, this is not true. Muscle proteins are not the preferred source of energy and hence they are degraded only after the body goes into starvation mode. 

Intermittent fasting might actually be good for bodybuilders as it shreds body fat while maintaining muscle mass. This gives more definition to muscles and a more muscular physique. 

Intermittent Fasting Bodybuilding: What Do the Latest Scientific Studies Say?  

Undoubtedly, intermittent fasting is one of the best ways to lose weight. However, when it comes to bodybuilding, people often turn skeptic. 

It is prevailing wisdom among common people that fasting is a form of starvation, simply because you are hungry while fasting. Lifting heavy weights while fasting does not seem like a good idea to build muscle, right? 

However, science has something different to say about the link between intermittent fasting and muscle growth. 

Let’s look at the most recent scientific evidence on this. Notably, all of the studies below have been conducted in humans.  

  • Intermittent Fasting with Resistance Training Improves Muscle Strength

A team of researchers from the U.S. compared the effects of resistance training (RT) with and without time-restricted fasting (TRF) in young males. 

TRF is a form of intermittent fasting in which a person typically consumes all of the foods within the 8- to 12-hour daytime window. 

After eight weeks of resistance training, participants in the time-restricted fasting achieved improvements in muscle strength and endurance. The gains were comparable to those in participants who did not follow TRF. 

The results clearly show that reduced energy intake (during intermittent fasting) has no or little effect in lean muscle retention or muscle strength. 

The study appeared in the European Journal of Sport Science in 2017.   

  • Intermittent Fasting with Resistance Training Decreases Fat and Maintains Lean Muscle Mass

A team of researchers from Italy, the U.S., and Brazil examined the effects of the 16:8 diet and normal diet in healthy resistance-trained males. 

After eight weeks, they found that the 16:8 group had greater fat loss than the normal diet group. However, there were no significant changes in muscle strength and muscle mass in both groups. 

The researchers conclude that resistance training with intermittent fasting decreases fat without affecting muscle mass. 

The study appeared in the Journal of Translational Medicine in 2016. 

  • Intermittent Fasting with Endurance Exercise Maintains Muscle Mass and Reduces Weight

A team of researchers from the University of Illinois compared the effects of a combination of alternate-day fasting (ADF) and endurance exercise with either ADF or exercise alone. 

After twelve weeks, the researchers found that the combination of ADF and exercise was superior to ADF or exercise in reducing fat mass and stomach size. Participants in all groups had no significant changes in lean muscle mass. 

The study appeared in the journal Obesity in 2013. 

Based on the findings of these studies, we can say – irrespective of the type of physical activity, intermittent fasting is able to cause weight loss and maintain muscle mass

Thus, you are quite unlikely to lose your muscle mass when you exercise while fasting. 

How to do Intermittent Fasting Bodybuilding? Tips for Healthy Gains and Strong Muscle

With these expert-advised tips, you will not only be able to lose fat and maintain your muscle mass but may also gain a few pounds of pure muscle. 

Follow an intermittent fasting bodybuilding meal plan

Intermittent fasting bodybuilding is about strategic eating and exercising.

Hit your daily calories and macros. Make sure to eat 1 gram of protein per pound of body weight. 

On the feeding period, sip on your BCAAs (branched-chain amino acids). BCAAs such as valine, leucine, and isoleucine enhance protein synthesis in your muscle. Besides, they also reduce muscle protein breakdown. 

If you need a stimulant to get a burst of instant energy before your workout, consider taking caffeine. However, avoid taking large amounts of caffeine. Caffeine in large doses can make you feel jittery.

You may also consider taking exogenous ketones such as those containing go BHB to keep your energy levels high during the fasting days. 

Schedule Your Exercise Plan Strategically  

Scheduling your exercise plan to support intermittent fasting and bodybuilding is not rocket science.
For the best fat burn, exercise 2 hours before your eating window. If you want to feel more energetic, exercise during your fasting window.

It is important to experiment and choose what suits your body and your goals the best.

Or opt to choose 5:2 fasting and exercise on the feeding days and rest on the fasting days, simple as that.

Interesting Read: Leangains: A Simple, Science-Based Guide


Key Takeaways

  • Intermittent fasting bodybuilding is possible. However, it requires a sincere effort and expert-designed meal/exercise plan. 
  • Fasting is not equivalent to starving and fasting does not cause muscle loss. In fact, it may increase muscle strength. 
  • Intermittent fasting may result in optimal results for bodybuilders as it causes fat loss and lean muscle maintenance at the same time.
  • Consult an intermittent fasting expert to know what type of fasting protocol best suits your needs and goals. Click HERE to take a 60-sec quiz approved by experts and get your revolutionary personal fasting assistant!