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.”
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.
Pros: While 24 hours may seem like a long time to go without food, the good news is that this program is flexible. You don’t have to go all-or-nothing at the beginning. Go as long as you can without food the first day and gradually increase fasting phase over time to help your body adjust. Pilon suggests starting the fast when you are busy, and on a day where you have no eating obligations (like a work lunch or happy hour).
Fasting on keto can be incredibly beneficial, especially if you’ve reached a plateau and aren’t seeing results from the ketogenic diet alone. While it’s not required, keto intermittent fasting can bring the benefits of your diet to the next level and help optimize your health. It is also thought to speed up ketosis by helping your body burn through glycogen stores more quickly, which can help sidestep symptoms of the keto flu to get faster results.

Also, if you eat a big dinner the night before, I think you’ll be surprised by how much energy you have in the morning. Most of the worries or concerns that people have about intermittent fasting are due to the fact that they have had it pounded into them by companies that they need to eat breakfast or they need to eat every three hours and so on. The science doesn’t support it and neither do my personal experiences.

Many people achieve the best results by starting the ketogenic diet first and then beginning intermittent fasting several weeks later. Although this is a bit different from the classic approach to the keto-intermittent fasting diet, it works better for some individuals. This is because intermittent fasting, as previously mentioned, should be a natural process, during which you should not feel deprived and hungry.


While these five methods are the most well-known in terms of integrating periods of fasting into your eating schedule, there are many other similar philosophies based on meal timing. For those who prefer a more fluid, less rigid method, there’s also the concept of eating intuitively. Primal Diet proponent Mark Sisson is a supporter of the Eat WHEN (When Hunger Ensues Naturally) method, where dieters simply eat whenever their bodies ask them to. However, some believe this can also lead to overeating or overconsumption of calories, since our bodies’ hunger-induced choices may be more caloric than otherwise.

While the idea of fasting can be overwhelming, especially if you haven’t done it before, intermittent fasting can actually be a lot easier than many other types of eating plans. Since you are fasting for time restricted chunks of the day, you’ll be eating less food, which eliminates a lot of the stress around having to meal prep. During the periods of time in which you're eating, you’ll still want to focus mainly on healthy fats, clean protein, and carbohydrates from whole food sources—but this isn’t an excuse to hit the drive-thru and load up on sugar the rest of the time! Here are some of the effects of intermittent fasting:
Eat normally for five days of the week, taking in fewer than 600 calories on the remaining two days; fasting days should be non consecutive. This is a slightly less arduous variation of the every-other-day fasting plan, but it also puts you in the fasted state for significantly less time. Consider using this particular intermittent fasting schedule as a stepping stone to something more advanced.
Reheating coffee breaks down the components, resulting in a bitter taste. With no cream or sugar to balance the flavoring, black coffee will more immediately taste bitter when reheated. If you find you must reheat your black coffee, absolutely do not use the microwave. Reheating coffee this way will break down the aromas and cause your coffee to taste stale instantly.
It requires less time (and potentially less money). Rather than having to prepare or purchase three to six meals a day, you only need to prepare two meals. Instead of stopping what you’re doing six times a day to eat, you simply only have to stop to eat twice. Rather than having to do the dishes six times, you only have to do them twice. Rather than having to purchase six meals a day, you only need to purchase two.
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