Intermittent Fasting & Building Lean Muscle for Women: What You Need to Know

by Dr. David Minkoff January 14, 2021 4 min read

Athletic female stretching and getting ready to go for a run on a forest trail.

If there is anything society has come to realize over the last century, it is that women are just as powerful, smart, ambitious, and capable as men. And while society as a whole is still catching up as far as true equality, the facts are evident when you look at some of the most incredible and influential people today.

When it comes to fitness, however, men and women are not the same. The natural, physiological differences necessitate unique approaches to achieve optimal results. While the fundamental science behind attaining a shredded, lean physique is basically the same for both sexes, the exact steps and application require careful consideration.

Intermittent fasting, for example, applies very differently to women than it does to men.

Men have much less complex endocrine functions and can subject their bodies to more extreme stress without causing adverse health effects. Women, on the other hand, must be more careful and precise with their routines to maintain hormonal balance and health.

Thankfully, there are steps a woman can take to become a lean machine and achieve an ideal physique.

Intermittent Fasting as a Woman

If you do a quick online search, you will find a wide range of advice regarding whether women should do intermittent fasting. Some popular fitness influencers indicate that women should never fast, while others claim that women can fast in the same way men do.

The truth is that each woman is unique, and what works for one woman will not work for all women.

Scientific research on the subject is limited, but animal studies have shown that intensive IF programs in females have caused significant health problems, including:

  • Reduced fertility
  • Increased stress
  • Menstrual changes
  • Reduction in ovary size


Does this mean women should never fast? Absolutely not.

It simply means that women should be careful and avoid intensive IF regimens. There is no “one size fits all” IF plan for women, and it is critical to start slow, while carefully observing your body’s reactions.

With that in mind, there are several IF methodologies that are relatively gentle on your body and can provide many of the benefits of IF without harming your health:

  • 16/8 Method: One of the most popular IF methods for both men and women is the 16/8 method, where you fast for 16 hours per day and then eat your calories during your 8-hour eating window. The 16-hour fasting window includes the time that you’re asleep. For example, you could eat your last meal at 8:00 PM and then fast until noon. If you choose this method, you should start with 14/10 and work your way up to 16/8.
  • The 5:2 Method: With the 5:2 method, you limit your caloric intake to 500 calories, two non-consecutive days per week. Again, start slow – possibly begin with limiting to 800 calories per day while observing the effects on your body.
  • Limited Alternate-Day Fasting: This method involves limiting your caloric intake to roughly 500 calories every other day but eating normally on non-fasting days.

Again, it is crucial to understand that a woman’s body reacts differently to stress. The first and most common reaction to undue physical stress in women is a partial or full shutdown of reproductive functions.  The underlying physiology of this relates to the increases in adrenaline and cortisol (stress hormones) along with decreases in signaling hormones like GnRH, LH, and estradiol. These changes can stop your body from menstruating and put your body in a “fight or flight” modality, which can be very detrimental long-term and lead to a wide range of other hormonal changes, imbalances, and health issues.


So, no – you do not want to put your body under continuous stress!

To put this in perspective: as long as you are smart, gentle, and careful not to put undue stress on your body, you can easily enjoy the enhanced metabolism, improved health, and weight loss that come with intermittent fasting.

How to Build Lean Muscle as a Woman

There are three key factors involved in achieving a lean, athletic physique:

  1. Cut out processed and empty carbs
  2. Supply your body with the nutrients it needs to thrive and build muscle while burning fat
  3. Exercise in the direction of building muscle

And yes, it really is that simple.

As a woman, you don’t necessarily want to load yourself with six protein shakes per day to bulk up huge biceps. Instead, you want to make sure that you have the right carbohydrates and dietary fats to supply your body with energy. At the same time, you want to provide your body with the amino acids it needs to maintain hormonal and digestive health while you build muscle.

Doing high-intensity interval training (HIIT), light weight training, and good cardio can help your body build muscle and enhance your metabolism.

Calorie-counting and forcefully starving yourself, as is apparently popular for many young women, is actually the polar opposite of what you should do. Eating too little food slows down your metabolism and triggers a chain reaction of hormonal effects that can make it virtually impossible to get in shape. And in fact, eating right and building muscle actually reduces ghrelin (a 28 amino acid peptide hormone that stimulates appetite) production – which makes you less hungry!


If you look at the diets of some of the most athletic women, such as Amanda Bisk, you can quickly see that the trick is putting the right foods into your body – not avoiding food altogether. Her story is a perfect example of a woman taking control of her diet and physical health, giving her body the nutrition it needs, and experiencing an athletic resurgence that put her in the best shape of her life.  She now looks at each meal as a chance to heal her body and feed it healthy and nourishing food.


Your body is unique, with unique requirements. There is no single diet that will work for everyone – you need to apply basic principles and customize your diet for yourself.

Good luck!



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*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.