In animal studies, after two weeks of intermittent fasting, female rats stopped having menstrual cycles and their ovaries shrunk while experiencing more insomnia than their male counterparts (though the male rats did experience lower testosterone production). (6) Unfortunately, there are very few human studies looking at the differences between intermittent fasting for men and women, but the animal studies confirm our suspicion: Intermittent fasting for long periods of time can sometimes throw off a woman’s hormonal balance, cause fertility problems and exacerbate eating disorders like anorexia, bulimia and binge eating disorder.
How It Works: Warriors-in-training can expect to fast for about 20 hours every day and eat one large meal every night. What you eat and when you eat it within that large meal is also key to this method. The philosophy here is based on feeding the body the nutrients it needs in sync with circadian rhythms and that our species are “nocturnal eaters, inherently programmed for night eating.”
Intermittent fasting (specifically the 5:2 diet) became popular in the UK in 2012[14][15][16] after the BBC2 television Horizon documentary Eat, Fast and Live Longer.[17] Via sales of best-selling books, it became widely practiced.[18][19] In the United States, intermittent fasting has become a trend among Silicon Valley companies.[20] According to NHS Choices as of 2012, people considering the 5:2 diet should first consult a physician, as fasting can sometimes be unsafe.[18][21] A news item in the Canadian Medical Association Journal expressed concern that promotional material for the diet showed people eating high-calorie food, such as hamburgers and chips, and that this could encourage binge eating since the implication was that "if you fast two days a week, you can devour as much junk as your gullet can swallow during the remaining five days".[22]
How It Works: This one’s easy: Eat very little one day, and eat like normal the next. On the low-calorie days, that means one fifth of your normal calorie intake. Using 2,000 or 2,500 calories (for women and men, respectively) as a guide, “fasting” (or “down”) day should be 400 to 500 calories. Followers can use this tool to figure out how many calories to consume on “low-calorie” days.
So if both musicians and adamantium-clawed superheroes do Intermittent Fasting, it can probably work for you too, if you can make it work for your particular lifestyle and situation! If you’ve tried implementing something like this in the past and not had success, or you’re just looking for guidance from a coach to help you implement it into your lifestyle, I hear ya!
I was very curious about this, so I asked the opinion of metabolic expert Dr. Deborah Wexler, Director of the Massachusetts General Hospital Diabetes Center and associate professor at Harvard Medical School. Here is what she told me. “There is evidence to suggest that the circadian rhythm fasting approach, where meals are restricted to an eight to 10-hour period of the daytime, is effective,” she confirmed, though generally she recommends that people “use an eating approach that works for them and is sustainable to them.”

What better way to nourish your bones and joints than by consuming more of the nutrients already found within them, including hyaluronic acid, glucosamine, chondroitin, calcium, and magnesium. Bone broth contains all of these nutrients, plus several amino acids that support joint mobility and healthy inflammatory response like glycine proline. It’s for these reasons that bone broth is becoming a go-to drink among athletes.
In fact, the authors of this book said that they had patients who only changed their eating habits with this twelve- to sixteen-hour “fruit” fast each day. They did not follow the diet’s other rules or count calories, and they still lost weight and got healthier. This strategy might have simply worked because the dieters replaced junk food with whole foods. In any case, people found this dietary change effective and easy to make. Traditionalists won’t call this fasting; however, it’s important to know that you may have options if you absolutely can’t abstain from food for several hours at a time.
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.
Tons of celebs are jumping on the intermittent fasting keto bandwagon, and for good reason. The two work hand in hand to accelerate weight loss, not to mention stimulate lots of other performance-boosting benefits. Fasting is an extraordinary tool for improving your biology. It’s free. It’s universally accessible. It’s adaptable. It’s the reason it’s always been a major part of the Bulletproof Diet.
When the female body senses it’s headed towards famine, it will increase the production of the hunger hormones, ghrelin and leptin, which signal the body that you’re hungry and need to eat (2). Additionally, if there’s not enough food for you to survive, your body is going to shut down the system that would allow you to create another human. This is the body’s natural way of protecting a potential pregnancy, even if you’re not actually pregnant or trying to conceive.
Intermittent fasting may work amazingly well for some people, and terribly for others. Most importantly, if you do decide to give intermittent fasting a try, be sure to listen to your body’s feedback. Easing into intermittent fasting by starting with shorter fasting windows can help with initial symptoms of hunger and discomfort. But if it becomes too uncomfortable, be honest with yourself, accept it, and move on.
The fasting phase of The Warrior Diet is really more about “undereating.” During the 20-hour fast, you can eat a few servings of raw fruit or veggies, fresh juice, and a few servings of protein, if desired. This is supposed to maximize the Sympathetic Nervous System’s “fight or flight” response, which is intended to promote alertness, boost energy, and stimulate fat burning.
In so far as insulin promotes de novo lipogenesis and suppresses lipolysis in adipocytes it DOES help keep the fat inside. But in Hyperinsulinemia / Insulin Resistance with Impaired Glucose Tolerance lipolysis may not be sufficiently reduced and fatty acids and glycerin can be spilled at the same time that Triglycerides are being formed & stored. In the liver the glycerin gets converted to glucose producing hyperglycemia.
And while this may sound difficult, it’s really not. After all, the reasons our bodies store fat in the first place is because we, as a species, aren't really designed for constant eating. The three-square-meals (or more) eating plan is a relatively new phenomenon in human history; for much of our past, feast and famine were the order of the day. Our bodies know how to handle long stretches without food, and they know how to make good use of the “feasts” when they come along.
This content is strictly the opinion of Dr. Josh Axe and is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of medical advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Axe nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.

Zero-calorie beverages are okay.  I drink green tea in the morning for my caffeine kick while writing. If you want to drink water, black coffee, or tea during your fasted period, that’s okay.  Remember, don’t overthink it – keep things simple! Dr. Rhonda Patrick over at FoundMyFitness believes that a fast should stop at the first consumption of anything other than water, so experiment yourself and see how your body responds.


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As a functional medicine practitioner, I see a wide range of health problems that all stem from chronic inflammation. And while acute inflammation is a natural and healthy response to help fight off pathogenic bacteria and infections, long-term chronic inflammation that doesn’t subside when the threat is gone can contribute to everything from autoimmune conditions to cancer.
Hi Thea, That’s wonderful that IF has worked for you. Diets, and particularly fasting, can be very triggering for others with a history of an eating disorder. People who have been in remission can relapse. For more about what concerns and problems others have had, there is alot of information out there, and for starters I recommend this thorough article from Psychology Today: https://www.psychologytoday.com/us/blog/hunger-artist/201411/the-fast-diet-fast-route-disordered-eating

As with Kinobody, the owner of Kinobody Greg O’Gallagher recommends you use coffee as a tool while helping you lose weight. Using coffee, to be more specific, black and only black coffee. Black as a skillet, coffee. No added sugar, creamer, sweeteners, or bulletproof coffee (that contain a mixture of stuff, mostly fats). Just ground up java bean and water heated until hot. I would also interject and recommend filtered water, or as I like to say, “use a filter or be the filter.” Who knows what lurks in the water we drink, and for that reason, let’s be cautious and use a filter.
Low carb diets are designed to force your body to burn stored fat as its primary source of fuel. With a typical diet, carbohydrates are burned first, followed by protein, and then fat as the final source of fuel. However, because most people consume far more carbohydrates than are necessary, the excess calories are stored as fat and weight loss is difficult to achieve.
Most of us have contemplated going on a diet. When we find a diet that appeals to us, it seems as if it will be a breeze to do. But when we get into the nitty gritty of it, it becomes tough. For example, I stay on a low–carb diet almost all the time. But if I think about going on a low–fat diet, it looks easy. I think about bagels, whole wheat bread and jelly, mashed potatoes, corn, bananas by the dozen, etc. — all of which sound appealing. But were I to embark on such a low–fat diet I would soon tire of it and wish I could have meat and eggs. So a diet is easy in contemplation, but not so easy in the long–term execution.
Low carb diets are designed to force your body to burn stored fat as its primary source of fuel. With a typical diet, carbohydrates are burned first, followed by protein, and then fat as the final source of fuel. However, because most people consume far more carbohydrates than are necessary, the excess calories are stored as fat and weight loss is difficult to achieve.

Because it simplifies your day. Rather than having to prepare, pack, eat, and time your meals every 2-3 hours, you simply skip a meal or two and only worry about eating food in your eating window. It’s one less decision you have to make every day. It could allow you to enjoy bigger portioned meals (thus making your tastebuds and stomach satiated) and STILL eat fewer calories on average.
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