Mythbusters: Intermittent Fasting Burns Your Muscles Instead of Fat

how to lose fat and gain muscle with intermittent fasting

The more intermittent fasting grows in popularity, the more false information about it circulates the Internet. You’ve likely come across many factual benefits of time-restricted eating, such as improved blood pressure and reduced insulin resistance. But you’ve probably encountered quite a few myths, too. 

Luckily, Simple is here to demystify some of the more wacky things you might have heard about intermittent fasting – like it burns your muscles instead of fat. Keep reading as we debunk one of the most common myths about time-restricted eating: how to lose fat and save muscle with intermittent fasting. 

What Happens When You Lose Weight?

You shed much more than unwanted body fat when you lose weight. When you lose pounds, you drop bodily fluids, visceral fat, lean body mass, and, most importantly, water weight. 

Water weight is the retention of fluids that can collect in your tissue due to poor nutrition, stress, or hormonal changes. Instead of releasing the fluid, your body stores it between your organs and skin. You may refer to this water weight as bloating. 

When you begin an intermittent fasting protocol, your body will run low on carbohydrates and use stored glycogen for energy instead. Glycogen is a sugar molecule that needs water to activate. Your body dips into your water stores to metabolize glycogen for energy. 

Your body will begin to burn fat after it’s drained your water-bloat. You may have heard that this process burns muscle, too. However, studies show that you can burn fat while gaining lean muscle during intermittent fasting.

Does Intermittent Fasting Help You Gain Muscle?

Exercise is the most common way to grow muscle, but it’s the chemical processes in your body that help you gain lean body mass. During conventional exercises, such as weight lifting, your muscle fibers sustain damage or injury. Your body then fuses these fibers to repair them, resulting in increased mass and size of your muscles.

intermittent fasting and muscle recovery

However, certain hormones play a crucial role in muscle gain and repair. Testosterone, insulin growth factor, and human growth hormone (HGH) are all necessary to gain and maintain muscle. This combination of hormones is where intermittent fasting and muscle recovery go hand-in-hand. 

During intermittent fasting, your testosterone levels can increase up to 180 percent. Scientists found intermittent fasting can reduce insulin resistance, which means your body is left with less excess sugar to store as body fat and more energy to supply the muscles. Plus, studies show a 24-hour fast can increase HGH production by a whopping 2,000 percent in men and 1,300 percent in women after a 24-hour fast.

These phenomena show intermittent fasting may be more efficient for gaining muscle mass during weight loss than traditional diets. A 2016 study comparing time-restricted eating to calorie-restricted eating found the intermittent fasting group increased lean mass by 2.2% while the calorie restriction group only gained 0.5 percent. 

The study implies fasting may be up to four times more effective at preserving muscle than cutting calories. Plus, the fasting group lost more than double the amount of visceral (or belly) fat than the carb-cutting group.

Scientific Opinion on Intermittent Fasting and Building Muscle

In a controlled study of intermittent fasting versus a calorie-restricted diet, scientists found intermittent fasting is more useful for maintaining lean mass. While both methods can lead to weight loss, studies show time-restricting eating can cause you to lose 0.4 kg less lean muscle mass on average than a calorie-restricted diet. Moreover, intermittent fasting enhanced muscle growth and endurance more than calorie restriction.

Most scientists agree that, at a minimum, it’s possible to maintain muscle mass while fasting. You don’t need to burn muscle instead of fat, nor will your body automatically burn muscle while fasting. 

It’s possible to lose a bit of muscle mass when you fast, as you also lose water weight and visceral fat. However, it’s more likely you’ll maintain muscle mass rather than lose or gain it. And with the proper plan in place, you can intermittently fast and build muscle. If you want to make sure you have the right fasting plan in mind, take our quiz and be 100% sure that your fasting plan suits your needs.

How to Intermittent Fast and Build Muscle

If you’re wondering how to gain muscle while losing weight on intermittent fasting, the answer lies in a healthy lifestyle. It’s possible to maintain and build muscle while in a fasting state, but you’ll need to put in a little effort. 

Exercise is crucial. Exercising during intermittent fasting is a healthy way for you to burn more fat and build muscle. As you fast, your body produces more human growth hormone (HGH) and testosterone while battling insulin resistance. Together, this recipe helps you build more muscle, recover faster, and maintain your gains.   

Aim to complete at least 30 minutes of aerobic exercise while in your fasted state, including:

  • Running
  • Jogging
  • Walking
  • Swimming
  • Dancing
  • Kickboxing

If running or jogging is uncomfortable on your joints, try a low-impact aerobic exercise like riding a bicycle or elliptical instead. Researchers found just 25 to 40 minutes of low-impact aerobic exercise can help preserve muscle and lubricate the joints during weight loss. But most importantly, include basic weight-lifting into your routine if you’re aiming to bulk up. 

Proper Nutrition for an Intermittent Fasting Muscle Gain Meal Plan 

If you choose to work out while in your fasted state, it’s essential to supply your body with the nutrients it needs to recover. But it can be challenging to pack in as many nutrients as possible during your feasting window. So, begin with protein.

intermittent fasting and muscle gain

Adhering to a protein-packed diet can help support muscle recovery during fat loss. Aim to consume a minimum of 20 grams of protein to preserve muscle gained through fasted exercise. Think beyond meat—nuts and seeds, leafy greens, and dairy such as Greek yogurt are full of protein. 

Plus, be sure to drink plenty of water. The first place your body will go to replenish energy while fasting is your glycogen and water reserves, so it’s critical you remain hydrated. In addition to drinking water, add in water-rich veggies such as cucumbers, celery, and tomatoes. By providing your body with proper fluid levels, you can repair and maintain muscle mass.

If you find it challenging to consume enough protein or other crucial vitamins and minerals, consider taking a supplement. However, check with your doctor first to be sure supplements are right for you. Though, if you lack protein, iron, or calcium, you may want to consult a physician about the healthiest way to include these minerals in your meals. 

How to Lose Fat and Gain Muscle with Intermittent Fasting

Have you been holding off on trying intermittent fasting because you were concerned it would burn your muscles? Consider that myth busted. With a time-restricted protocol and proper eating plan and exercise, you can maintain muscle, increase lean body mass, and shed belly fat.

Author's bio


Grace Trumpfeller

Grace is an avid health and wellness advocate with nearly a decade of experience in the diet and nutrition industry. With a vast background in journalism and creative writing, her core focus is to empower individuals to reclaim their health and vitality by providing expert advice rooted in ...