Does Intermittent Fasting Cause Muscle Loss?

Written By Michael Hall

Proud father of two beautiful daughters and a seasoned ISSA certified personal trainer with over 15 years of experience in the industry. 

The idea of “starving” oneself to achieve one’s desired physique is nothing new; however, the concept of intermittent fasting has brought renewed interest in how certain eating patterns may affect our bodies.

Intermittent fasting involves periods of extended calorie restriction or abstaining from food entirely for specific periods. Proponents claim that it boosts metabolism and aids in fat loss while still allowing you to eat your favorite foods during non-fasting times. But could something so seemingly simple also have negative consequences?

One possible consequence of intermittent fasting is muscle loss – when there are not enough calories coming into the body, the body will begin breaking down its own muscles as fuel instead. This obviously isn’t desirable if your goal is building lean mass! So then, just how much risk do practitioners face when engaging in intermittent fasting? 

What Is Intermittent Fasting?

Intermittent fasting is an eating pattern that cycles between periods of eating and fasting. It’s a popular dieting method for those who want to lose weight and improve their overall health. Generally, people will fast for 16-24 hours and then eat normally during the ‘feeding’ window. This could mean skipping breakfast or lunch and having one meal later in the day. 

There are many different types of intermittent fasting plans, such as 16/8 (where you abstain from food for 16 hours each day and have 8 hours to consume meals), 5:2 (regularly eating five days per week but restricting calories on two nonconsecutive days) and alternate-day fasting (which involves alternating between 24-hour feeding windows and 24-hour fasting windows). Each type has its own benefits and drawbacks, depending on your lifestyle.

No matter what plan you choose, there is strong evidence showing that intermittent fasting can help with weight loss, reduce inflammation, lower cholesterol levels and even increase lifespan. However, many people wonder if this kind of dietary approach might lead to muscle loss.

Relationship Between Intermittent Fasting And Muscle Loss

Now that we understand what intermittent fasting is, let’s look at how it relates to muscle loss. While some people believe that intermittent fasting causes an increase in muscle loss, this is not necessarily true. When done correctly and consistently, intermittent fasting does not cause significant muscle loss. However, there are certain factors that can contribute to decreased muscle mass if the dieter is not careful.

First, any extreme dietary changes should be accompanied by regular exercise and adequate hydration. Without proper nutrition and supplementation, the body may experience a decrease in lean body mass due to a lack of nutrients needed for healthy muscles. Additionally, those who do not consume enough calories during their fasted state may also be prone to losing more lean body mass than those who eat regularly throughout the day. It’s important to note that individuals with medical conditions or impairments may need additional guidance before engaging in any type of fasting regimen as well.

When incorporated into a healthy lifestyle consisting of strength training exercises and nutrient-dense meals during non-fasting periods, intermittent fasting can actually lead to improved performance levels and increased muscular gains over time. With mindful consideration of caloric intake and physical activity levels each day, following a pattern of eating, such as intermittent fasting, could potentially help preserve lean body mass rather than deplete it.

Benefits Of Intermittent Fasting For Muscle Building

According to a 2015 study, intermittent fasting was found to improve body composition in resistance-trained individuals. This is because it helps with fat loss while maintaining muscle mass and strength.

The benefits of intermittent fasting for muscle building include:

Improved metabolic health:

Better nutrient partitioning:

  • Maximized protein synthesis and utilization of amino acids
  • Enhanced anabolic hormones like growth hormone (GH) and testosterone

Improved energy efficiency and performance:

  • More efficient use of stored energy sources during workouts
  • Faster recovery times between sets/exercises due to increased GH concentrations.

Intermittent fasting can benefit both experienced athletes looking to gain muscle and those just beginning their fitness journey. It is also essential for people who want to achieve long-term results, as it will help them maintain lean muscle without compromising their overall health.

Best Practices For Intermittent Fasting To Prevent Muscle Loss

However, with intermittent fasting comes the risk of muscle loss. To prevent this from happening, there are a few tips to follow. First and foremost, it is essential to consume adequate protein throughout the day for muscles to repair themselves after exercise. This means aiming for approximately 0.8-1g/kg of body weight per day spread over four meals or more. Additionally, healthy sources of fats such as avocados, nuts, seeds, and oils can help maintain energy levels during fasting periods and support hormone production that helps build muscle mass.

When engaging in intermittent fasting, it is also important to prioritize strength training sessions instead of cardio workouts which can lead to further muscle tissue breakdown and catabolism. A combination of heavy compound movements such as squats, deadlifts, presses, and pull-ups will increase muscle size while reducing fat stores at the same time. Doing these exercises 2-3 times a week should be enough to stimulate growth without losing too much muscle tissue during fasting windows.

Finally, consuming sufficient amounts of carbohydrates around your workout window may be beneficial for maintaining lean muscle mass when using an intermittent fast protocol. Eating about 1–2g/kg bodyweight before and after your workout allows you to perform better in each session while providing fuel for recovery afterward. In addition to this, focusing on whole food carbs like sweet potatoes, quinoa, or oats prevents any spikes in insulin levels that could impede progress towards your desired fitness goals.

Common Misconceptions About Intermittent Fasting And Muscle Loss

Many people believe that intermittent fasting causes muscle loss. But is this really the case? This question has been on many minds, and it’s time to dispel the myths and uncover the truth. Let’s take a closer look at the common misconceptions about intermittent fasting and muscle loss!

To start, there are those who think that if you don’t eat for long periods, your body will go into starvation mode and begin breaking down its muscles for energy. This simply isn’t true; research shows that short-term fasting does not lead to a significant decrease in lean mass or strength. In other words, it won’t cause you to lose muscle unless you’re already severely undernourished.

Finally, some people may worry that they’ll be too hungry during their fasts to exercise effectively and build muscle. However, studies have shown that even after 24 hours without food, most people maintain enough energy levels to hit the gym without problems. So while it’s important to make sure you get enough nutrients pre-and post-workout, intermittent fasting doesn’t necessarily interfere with your progress in terms of building muscle.

Contrary to popular belief, intermittent fasting does not usually lead to significant muscle loss – as long as proper nutrition is maintained before and after workouts.

Overtraining and Under-recovery

Overtraining and under-recovery are two of the most common causes of muscle loss due to intermittent fasting. Overtraining is when an individual exercises beyond their current physical abilities, decreasing strength, endurance, and overall performance. This can be caused by not giving your body enough time to recover between workouts or doing too much intense activity at once. On the other hand, under-recovery occurs when an individual does not get enough rest or sleep after working out. Without sufficient rest, the body cannot adequately repair itself from exercise-induced damage and therefore cannot build muscle effectively.

Intermittent fasting can also increase levels of stress hormones such as cortisol in the bloodstream, leading to increased muscle breakdown over time. Cortisol has been shown to inhibit protein synthesis, which is necessary for building new muscle tissue. Additionally, prolonged periods of hunger may reduce testosterone levels, which regulate muscle growth and recovery.

It’s important for those taking part in intermittent fasting to pay attention to how their bodies respond during and after each workout session; if they feel fatigued or weak, then it could be a sign that they’re overtraining or under-recovering from their previous sessions and need more rest before continuing with strenuous activities. Taking adequate breaks between sets and meals will help ensure proper nutrition while avoiding any potential adverse effects on muscles associated with intermittent fasting.

Lack Of Proper Nutrition During Fasting Periods

Much like a car running out of fuel, intermittent fasting can lead to muscle loss if proper nutrition is not considered. The body needs the right fuel to maintain its muscles and prevent them from wasting away. During periods of fasting, the body will use up available energy stores to replace what it has lost. This can cause muscle mass to decrease, resulting in weaker muscles and less strength over time.

Without the nutrients your body needs for optimal performance during fasting periods, you are essentially driving on empty. Your muscles become starved for essential vitamins and minerals needed for healthy growth and development. To ensure that your muscles stay strong, it’s important to provide them with adequate amounts of protein as well as other key building blocks such as carbohydrates and fats before engaging in any type of intermittent fasting program.

When done correctly, following a strategic nutrition plan while participating in intermittent fasting can help protect your muscles from being broken down too quickly. Relying on nutrient-dense foods may be beneficial when reaching specific health or fitness goals without risking unwanted consequences caused by inadequate intake levels. Taking this into consideration can help you reap all the benefits associated with periodic fasting without having to worry about losing precious muscle mass along the way.

Frequently Asked Questions

What Type Of Diet Should I Follow While Intermittent Fasting?

The idea of intermittent fasting is becoming increasingly popular, but it can be intimidating to know what diet to follow while fasting. With so many different diets out there and the potential risks associated with this form of eating, it’s important to ensure that your nutritional needs are met.

What should you do? Well, in a nutshell, the answer boils down to simple – keep your diet as balanced as possible! Eating nutrient-dense foods during each meal will help ensure that your body has all the essential building blocks for proper functioning. This includes lean proteins like fish or chicken, complex carbohydrates like whole grains and legumes, healthy fats such as nuts and avocados, and plenty of fresh fruits and vegetables. Additionally, making sure that you’re drinking enough water throughout the day is key for keeping hydrated.

But don’t worry – following an intermittent fasting lifestyle doesn’t mean completely giving up on any deliciousness! You can still indulge in treats from time to time without compromising your health goals; just remember moderation is key here. In other words, if you want something sugary once in a while then go ahead – just make sure not to overdo it. Allowing yourself some indulgence now and then can help you stay motivated by providing positive reinforcement when it comes to sticking to your plan overall.

So whatever type of diet you choose while intermittently fasting, make sure it fits into your lifestyle and dietary preferences while ensuring you get all the nutrients needed for optimal health benefits. The bottom line: balance is key!

How Long Should I Fast For?

When it comes to intermittent fasting, how long you fast can be critical in determining the success of your diet. It’s important to ensure that you follow a healthy and sustainable plan so that you don’t end up causing yourself harm instead of helping yourself. Here are four key points to consider when deciding on an appropriate length of time for your fasting period:

1. The type of fasting – Different types of intermittent fasting may require different lengths of time spent not eating. For example, if you choose alternate-day fasting instead of 16/8 hour fasting, the amount of time between meals will vary greatly.

2. Your health goals – Depending on the results or changes you’re looking for from intermittent fasting, the duration may differ accordingly. If weight loss is your goal, shorter periods might work best; however, if you are trying to improve metabolic markers such as insulin sensitivity, longer periods may be more helpful.

3. Your lifestyle – Your current lifestyle should also influence the time that works best for you while practicing intermittent fasting. If you have a demanding job or a very active social life and find it challenging to fit in extended mealtimes every day, then maybe something like a 16/8 model would suit you better than 24 hours at once two days per week.

4. Safety concerns – Perhaps most importantly, safety must always come first regarding any dietary change or experiment with food intake and timing! Make sure before beginning any sort of regimen involving meal skipping that it is safe for your body and mind, given your individual circumstances (such as pre-existing medical conditions).

When making decisions about how long to fast during intermittent fasting cycles, there’s no one size fits all answer. Everyone has their own unique needs and preferences, which need to be taken into account when tailoring a plan specifically suitable for them. The good news is that by taking these four elements into consideration prior to starting out on your journey with IF, you’ll be much better equipped towards finding the right balance between short-term gains and long-term successes!

How Much Muscle Can I Expect To Lose With Intermittent Fasting?

When discussing intermittent fasting and its effects on muscle loss, one of the most frequently asked questions is: how much muscle can I expect to lose? This is an important inquiry as it helps us determine whether or not this dieting strategy will benefit our health and fitness goals.

Intermittent fasting has been studied in recent years, and research shows that it does not cause significant muscle loss. However, when done incorrectly, such as with extreme calorie restriction or excessive periods without food, there can be more pronounced losses in muscle mass.

It’s important to remember that everyone responds differently to different diets and exercise regimes, so understanding your personal needs is key when considering any type of dietary change. If you want to try intermittent fasting but are worried about potential muscle loss, consult a healthcare professional first and get enough protein while following this plan. Taking these precautions should ensure that you experience minimal negative impacts from your chosen dieting strategy.

What Are The Long-Term Effects Of Intermittent Fasting?

Intermittent fasting has become an increasingly popular trend as a way to promote weight loss, but it is worth exploring its long-term effects. With this in mind, let’s take a look at what the long-term effects of intermittent fasting might be:

On Weight Loss:

  • Positive Effects: Studies have shown that intermittent fasting can lead to increased fat-burning and improved metabolic health. Additionally, it can reduce hunger levels and help individuals stick to their diet plans over time.
  • Negative Effects: While some studies show positive results, others suggest that after prolonged periods of time, the body begins to adapt and become resistant to any further changes in weight loss. This could mean that while you may see initial success from intermittent fasting, your progress may slow down or stop entirely if sustained for too long.

On Muscle Mass:

  • Positive Effects: Intermittent fasting can help preserve muscle mass during weight loss due to its ability to increase protein synthesis and improve recovery times between workouts.
  • Negative Effects: Longer term use of intermittent fasting can potentially put stress on the body, leading to muscle breakdown if not combined with proper nutrition and exercise habits. It is important to note that muscle losses will vary depending on individual circumstances such as age and activity level.

Finally, although there are both positive and negative aspects associated with intermittent fasting when used in the long term, it is essential to understand how your own lifestyle factors into these outcomes. Taking steps towards creating healthy eating habits throughout the day coupled with regular physical activity should always be kept top of mind when considering any dietary change.


In conclusion, intermittent fasting is a popular dieting strategy that can be beneficial for weight loss. However, it comes with certain risks, particularly in muscle loss. 

It’s important to remember that intermittent fasting isn’t a one-size-fits all approach to health and nutrition; everyone’s needs are different. Before you begin this type of dieting regimen, talk to your doctor about what type of diet will work best for you and how long you should fast for each session. 

Ultimately, while there are potential risks associated with intermittent fasting, such as muscle loss, with the right guidance from medical professionals and smart lifestyle choices like eating nutritiously on non-fasting days, many people find success with this approach to achieving their desired goals.