|November 29, 2023

Intermittent Fasting for Women: What You Need to Know

By Dave Asprey
Reviewed for Scientific Accuracy

Intermittent Fasting for Women: What You Need to Know

It’s a common belief that intermittent fasting causes problems for women, and that can be true if you’re using traditional methods. The Bulletproof Diet incorporates intermittent fasting and has helped the women in my life feel good, look amazing, and be fierce.

More than a few women have found the Bulletproof Diet after running into problems from a few months of intermittent fasting. With traditional intermittent fasting, women can experience a myriad of symptoms, including:

  • Sleeplessness
  • Anxiety
  • Irregular periods
  • Hormone dysregulation
  • Brain fog

This matches what I see. Low calories lead to low energy, stress, and hormone imbalances in both men and women, but it happens faster in women. That’s one of the reasons I don’t believe in calorie restriction as a generally healthy practice.

This guide lays out the problems women experience with intermittent fasting, fat restriction, and calorie restriction, and shows you how to avoid all the negative effects with Bulletproof Intermittent Fasting.

Before we go any further, I should mention that pregnancy is a whole different ballgame. You shouldn’t do any kind of fasting or ketosis while pregnant unless your doctor tells you to.

Related: Ultimate Intermittent Fasting Guide

Why intermittent fasting is hard on a woman’s body

In both women and men, calorie (or fat) restriction sends your body signals to interrupt fertility. A low calorie or low-fat diet tells you body you’re in a famine, so a woman’s body gets stressed and stops being fertile until food supplies return to levels that can support reproduction.

If you’re a woman and you get pregnant during a famine, you have a much larger chance of major nutrient deficiencies or even death when you’re pregnant or nursing because of the incredible stress it puts on your body.

The woman’s body communicates fertility problems, hormone issues and nutrient deficiencies to potential mates in a number of ways. She may experience:

  • Hair loss
  • Weight gain
  • Acne
  • Excess body hair
  • Pale skin
  • Loss of libido
  • Lack of energy

You’re not vain because you want to avoid these things. The above symptoms, and others, are strong indicators of your overall health.  

In men, it’s a biological matter of convenience. If you reproduce during a famine, it’s uncomfortable, yes. But men don’t carry, birth, or nourish their babies. Women do, so women are more biologically sensitive to these effects than men and feel the problems first.

Enter Bulletproof Intermittent Fasting

I used biohacking principles to make Bulletproof Intermittent Fasting easier on the body than traditional intermittent fasting, for the simple fact that it’s wasteful to apply more stress to the body than is needed to make a change.

Bulletproof Intermittent Fasting is a simple way for both women and men to realize the benefits of intermittent fasting without the health risks.

Instead of going 18 hours without food, brew Bulletproof Coffee beans in the morning, and blend it with a nice big hunk of grass-fed butter and Brain Octane Oil for breakfast with no carbs or protein. If you use mold-tested Bulletproof Coffee beans, you have a satisfying, low-toxin coffee that doesn’t cause adrenal stress the way most coffee does, and it tastes like a creamy latte.

If you get hungry before lunch, blend up another one. You can use decaf Bulletproof Coffee or make one with matcha tea if you don’t want another cup of caffeine.

For the official Bulletproof Coffee recipe, head on over here.

Why Bulletproof Intermittent Fasting works for women

The fat keeps your body in ketosis so you get the cell renewing benefits of Intermittent Fasting, and the fats provide enough fuel for your brain so you don’t get the same stress response.

You get the energy a normal breakfast provides (more energy if you’re transitioning from the standard American dessert-breakfast) and you can still make hormones. You don’t even think about food until mid-afternoon if you’ve had Bulletproof Coffee for breakfast.

Bulletproof Intermittent Fasting tells a woman’s body that it’s time for the cells to clean house and to burn fat as energy. It preserves adrenal function more than normal IF. Since you’re actually using adrenal hormones () to burn fat, it’s a game changer for women.

On top of that, the cold hands, brain fog, irritability and tiredness that come in the afternoon with traditional Intermittent Fasting don’t exist with Bulletproof IF. Our bodies were made to use fat for fuel – if there’s enough fat, we do well, and our hormones work, and we can still lose weight.

Fertility and attractiveness

Bulletproof Intermittent Fasting also doesn’t signal that you’re in a famine and should shut down your fertility. In contrast, it sends the signal, “You are in a land of plenty, with an environment full of the types of fat that make for optimally healthy babies. Be fertile! Have babies!”

Chances are, you want the features associated with fertility and vitality, whether you’re ready for babies or not. You want your physiology to send out the signal that you are well-nourished and capable of producing strong offspring. This translates to attractive features:

  • Shiny hair
  • Radiant skin
  • Healthy libido
  • Proper weight
  • Energetic demeanor

It’s not superficial or shallow that both men and women seek certain features in a suitor. That’s your biology encouraging you to spend your energy and resources on an offspring that will have the best chance. Attractiveness clues you in to what’s happening on the inside.

Bulletproof Intermittent Fasting works better for men too. Several have reported that they broke through weight loss plateaus using Bulletproof Intermittent Fasting that other intermittent fasting protocols couldn’t touch.

Bulletproof Intermittent Fasting for your adrenals

There is a reason that you crave fatty and salty foods when you’re stressed – adrenal exhaustion. Listening to your body, then eating something soaked in grass-fed butter and coated with high-quality salt gives your adrenal glands what they need. Higher overall fat intake combined with a sprinkle of pink Himalayan salt can do wonders for adrenal function.

What does the science say about intermittent fasting for women?

Many thanks to Stefani Ruper of PaleoforWomen.com for writing an awesome results for women. It lays out the evidence that men and women react to diets differently.

Stefani’s “Paleo for Women” list of principles is worth repeating here, because she does a better job of describing what a Bulletproof evolutionary perspective does for women than I do:

With an evolutionary perspective, a woman does not work against but instead works with her body.
With an evolutionary perspective, a woman listens to her body.
With an evolutionary perspective, a woman does not see herself as separate from her body.
With an evolutionary perspective, a woman loves and respects her body.
With an evolutionary perspective, a woman is free.
With an evolutionary perspective, a woman feels good.  
With an evolutionary perspective, a woman looks amazing and real.
With an evolutionary perspective, chins come up.
With an evolutionary perspective, a woman is fierce.
With an evolutionary perspective, things aren’t perfect.

Amen, Stefani.

So, the idea that intermittent fasting is bad for women is only partially true. Your body will do strange things if it thinks it’s starving. That’s normal, expected, and part of your evolutionary biology. The key to making it work is to give your brain the energy it needs and assuring your metabolism that everything is a-o-k and you’re not in the middle of a famine or disaster.

Bulletproof Intermittent Fasting tips:

  • If you’re over 40 or overweight, add grass-fed collagen to your Bulletproof Coffee for 30 days. You will feel hungry earlier in the day than you would if you skipped the collagen, but it will re-set your leptin, one of your hunger hormones. Keep fructose and sugars to a minimum for optimal leptin levels as well.
  • Bulletproof green zone carbohydrates are great for carb re-feeding, but not in the morning.
  • If Bulletproof Coffee upsets your stomach, make sure you’re starting with one teaspoon Brain Octane Oil. Gradually work your way up to the full tablespoon. Using MCT oil or coconut oil in place of Brain Octane Oil can cause digestive upset as well. It’s not the same thing.


*This post has been updated to address some of the most common questions around intermittent fasting for women. Thanks for reading and have a great week!

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