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How to Gain Muscle During Intermittent Fasting: Key Things You Need to Know

Many questions arise when you begin intermittent fasting, many of which center around what you can and can’t eat. However, another common concern is the impact of intermittent fasting on your muscles.

As muscle building is associated with a significant calorie intake, it might make sense to believe fasting can be counterproductive for muscle builders. After all, won’t eating fewer calories lead to muscle mass loss?

This article will clarify the subject, from answering popular questions to sharing our top tips for holding onto your muscle mass while on a time-restricted eating routine.

Is It True That You Lose Muscle While Fasting?

One common misconception is that practicing intermittent fasting will lead to muscle loss. This fear often deters people from adopting this eating pattern, as they worry about losing strength and lean body mass. It’s also a frequent concern among fasting newcomers.

However, this assumption is unfounded, as intermittent fasting does not seem to cause more muscle loss than other weight loss methods.

Significant muscle loss can occur with weight loss through starvation. Still, intermittent fasting is not a starvation method—it’s an eating pattern that allows your body to deplete glycogen stores and enter a fat-burning mode in which your body will burn stored body fat rather than muscle tissue.

Muscle mass loss can occur with any form of restrictive eating. The key to avoiding it is to take care of your body by ensuring your muscles receive enough calories and nutrients to remain healthy. By making smart choices, you can prevent muscle protein breakdown.

In fact, intermittent fasting can potentially increase muscle gains by elevating certain hormones, such as testosterone and human growth hormone—both necessary to grow lean muscle.

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Can You Gain Muscle While Fasting?

Yes, you can gain muscle during intermittent fasting if you implement some necessary strategies.

Fasting alongside a normal diet won’t quite cut it—gaining muscle mass requires adjusting your diet to ensure sufficient calorie and protein intake. In addition, you must perform the proper strengthening exercises to target the muscles and aid muscle growth.

Let’s delve into these aspects in more detail.

You have to eat more calories than you burn

While weight loss requires a calorie deficit, building muscle demands a calorie surplus. This means you need to consume more calories than you burn, as calories fuel your body and assist in repairing and regrowing damaged muscle tissues for larger, stronger muscles.

When practicing time-restricted eating, it’s essential to consume enough calories during your feeding window. Consuming extra calories may lead to body fat gain, so choosing foods that muscles can utilize, such as high-quality protein sources, is essential.

To avoid gaining unwanted fat, it’s preferable to create a smaller calorie surplus and focus on gradual bulking.

You need to eat enough protein

Protein is the ultimate macronutrient for bodybuilding. It is essential for building and repairing the body’s tissues, providing muscles with the nutrients they need for growth and recovery. A higher protein intake is crucial when following a weight-loss diet.

To increase your protein consumption, opt for good-quality lean protein sources like lean beef, chicken, turkey, salmon, eggs, and peanut butter. When your eating window arrives, consume plenty of these healthy, protein-rich foods.

You need the right exercise

Combining intermittent fasting with resistance training promotes fat loss and preserves lean body mass. Fasting, along with physical activity, does not negatively impact muscle function. So, you can incorporate exercises like push-ups and squats with weight training.

Resistance training directly targets muscles, helping you to bulk up. While cardiovascular exercise is excellent for burning fat, it’s best to avoid high-intensity training while practicing time-restricted eating if your goal is to build muscle.

How to Maintain Muscle During Intermittent Fasting

If you want to lose weight with intermittent fasting while minimizing muscle loss, there are specific strategies you can adopt to maintain lean mass, good health, and a desirable body composition.

Here’s what you can do to ensure you don’t lose muscle mass.

1. Do weight training

Weight lifting is the optimal practice for maximizing muscle growth—it puts stress on the muscles, forcing them to adapt and strengthen. While cardio exercise is more effective for burning body fat, weight training also contributes to fat loss and overall weight loss.

To keep your muscles active, use dumbbells, resistance bands, and weight machines at the gym. It’s best to focus on workouts that engage all muscle groups, but you can also target specific areas that need extra attention, such as your legs and arms.

Ideally, schedule your weight training sessions during your eating windows. Intensive exercise in a fasted state can impair performance. Moreover, training in a fasted state might lead to muscle loss if the body starts breaking down protein to fuel your workout.

Save your training sessions for times when you can fuel your body with food. Alternatively, you could train before breaking a fast so that you can refuel immediately afterward.

2. Watch your calories and macros

To lose fat and preserve muscle, it’s crucial to monitor your macros and calorie intake during your eating window. On average, it’s recommended that men consume 2,500 calories per day and women 2,000 calories per day to maintain a healthy weight.

Calories are necessary to fuel your muscles. Therefore, if muscle building is your goal, you should increase your intake and consume a calorie surplus of around 200-300 calories. A typical macro ratio for muscle maintenance is 30-50% carbs, 25-35% fats, and 25-35% protein.

Sufficient protein intake is vital for healthy muscles. Protein is the most important nutrient, as it helps preserve muscle during your weight loss journey. To achieve muscle gains alongside weight training, aim to consume 0.5 to 0.8 grams of protein per pound of body weight.

3. It’s all about the balance of your foods

A balanced diet is crucial for success with intermittent fasting. Ensure you eat a variety of healthy foods, focusing on the major food groups such as lean proteins, healthy fats, complex carbohydrates, and fiber. This approach will provide your body with essential nutrients.

Here are some examples of foods in these groups:

  • Lean proteins — lean beef, skinless poultry, white-fleshed fish, tofu, beans, and plain Greek yogurt
  • Healthy fats — avocado, eggs, fatty fish, olive oil, nuts, and seeds
  • Complex carbs — brown rice, quinoa, sweet potatoes, and whole wheat bread
  • Fiber — broccoli, leafy green vegetables, lentils, kidney beans, and oats

4. The type of fasting matters too

Choosing the right intermittent fasting method is crucial to meeting your goals. This will depend on factors like your routine, your habits, or how long you can comfortably go without food.

The longer your fasting window, the more fat you will burn every day. But here’s the catch—extending your fasts will also mean that you’ll have less time to get all the calories you need to keep building muscles.

The most popular method for people aiming to build muscle while fasting is the 16:8 method. This fasting style involves consuming meals within an 8-hour window and fasting for the remaining 16 hours, which gives you enough time to consume a good amount of calories while also leading your body into an efficient fat-burning mode during the fasting window.

Regardless of the method you choose, fasting won’t make you build muscle on its own. If your goal is to see some muscle gains, it’s crucial that you choose a method that gives you enough energy to work out, either during or after your eating window—even if that requires fasting for fewer hours a day.

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5. You will still gain fat—prepare for that

You will still gain fat when trying to maintain muscle with intermittent fasting. This is because, to maintain muscle, you need to consume plenty of calories. Prolonged periods of fasting may even encourage your body to store fat as it prepares itself for starvation.

Fat gain is entirely normal, especially when you start bulking. This is why exercising is crucial—because it helps to improve muscle definition. So, don’t let this process deter you from your goals: your body will adjust accordingly.

6. Take supplements during your eating windows

Dietary supplements provide a convenient way to ensure you get your daily vitamins and minerals. During fasting, you risk missing out on essential nutrients that you would typically get from your regular diet. Insufficient nutrient intake can lead to a loss of lean mass.

Let’s explore some of the best supplements to take during your eating window:

  • BCAAs — branched-chain amino acids are one of the best supplements you can take for muscle health, as they help you build muscle while preserving your muscle mass while fasting. BCAAs also aid muscle recovery and alleviate soreness.
  • Pre-workouts — pre-workout supplements contain important vitamins and minerals to fuel your muscles and workouts while improving body strength.
  • Whey proteinwhey protein is great for helping you lose fat and build muscle. For maximum benefits, you can take it before, during, or after a workout.

7. Take the right supplements during your fasting periods

Taking supplements during your fasting window can make your fast more comfortable. However, some supplements can break a fast, so it’s crucial to assess the ingredients to determine how they might affect your insulin levels. After careful evaluation, you can utilize these products.

Some of the best supplements you can take to boost your fasting journey are:

  • Creatine — creatine is naturally present in the muscle cells and has many benefits for body composition. It is a popular supplement among athletes because it supplies energy to the muscles and works to increase strength and exercise performance.
  • Electrolytes — electrolytes are essential minerals that regulate several bodily processes, including supporting muscle and nerve function. Without enough electrolytes, you will likely experience muscle cramps that prevent you from getting the most out of your training sessions. You can take electrolytes in the middle of your fast to boost energy.
  • Fiber supplements — supplements are an excellent way to ensure you get enough fiber in your diet and keep your gut healthy. High-fiber intake supports weight loss, enhances body composition, and may increase lean mass. Generally, you can take these supplements at any time during your fast.
  • Probiotics — probiotics provide various health benefits for your gut but may help regulate muscle mass. You can absorb them better on an empty stomach, making them an excellent supplement for your fasting window.

8. Don’t push yourself too far

Knowing your limits is vital for maintaining lean mass—pushing yourself too far and training excessively will only exhaust your body. While you might be keen to build muscle, overtraining can damage your muscles and cause muscle loss.

Creating a healthy mindset and finding a balance between fasting, eating right, and training your muscles is crucial. Remember to allow time for muscle recovery and always listen to your body. Stop working out if you feel dizzy, weak, or lightheaded.

Who Should Not Exercise While Fasting?

Exercising while intermittent fasting is generally safe for most healthy individuals and is essential for muscle gain. However, working out during the fasting window can be more taxing on your body, so it’s vital to take precautions, like drinking plenty of water.

Some people may have health conditions that make exercising in a fasted state more problematic. Certain groups are better off skipping exercise while fasting, including:

  • People with type 1 or 2 diabetes and low blood sugar levels — fasting may cause blood sugar levels to drop too much, and exercise could worsen this.
  • People with coronary heart disease — exercise increases the heart rate and may increase the risk of cardiovascular events in people with this disease when in a fasted state, where training is more strenuous due to energy restriction.
  • People taking blood pressure medications — certain medications can impact heart rate and how the body reacts to physical activity.

Consulting your doctor can help you determine whether you should avoid exercise while intermittent fasting. They may suggest low-intensity workouts that support fat loss and muscle strengthening without putting excessive strain on your health.

Take Care of Your Muscles With DoFasting

Muscle gain and muscle maintenance are entirely possible while intermittent fasting with the right plan and strategy. But if you want better and faster results, you’ll probably need to go the extra mile and keep your muscles in good condition with a mindful diet and training routine.

You can make sure you’re getting all the calories you need for your muscle-building goals while keeping track of your fasts with the DoFasting app. It’s an excellent tool for finding the balance between losing weight and building muscle with intermittent fasting, providing features tailored to the needs of all kinds of fasters:

  • A fasting tracker to remind you when to start and finish your fasting windows
  • A range of exercises to add to your workout plan, including dozens of strength workouts for building muscle
  • Multiple recipes to add to your meal plan, so you can ensure you’re getting enough calories and protein in your diet to support muscle recovery and growth

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Intermittent Fasting and Muscle Gain: Final Thoughts

Intermittent fasting might not be the best choice for maximum muscle gain if your goal is to bulk up significantly in a short period of time.

However, fasting can help you secure lean muscle and even lead to some muscle growth while helping you lose excess body fat. All you need is to follow a tailored eating plan covering all your nutritional needs and a training routine including strength exercises.


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This is an evidence-based article that includes scientific citations. DoFasting’s professional writers and editors prepared the content, which a team of medical experts verified to be accurate.

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