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 is probably what you’d think. It’s fasting… intermittently. Or, to be a bit clearer, it’s skipping meals. But while missing a meal will certainly mean fewer calories throughout your day, the magic of intermittent fasting isn’t just in how it reduces food intake, but in how it helps your body make better use of the calories you keep.
This is excellent, thank you! One thing I would love to see added to this research is the keto effect of just water over those 120 minutes, and THEN the keto effect of adding a tad bit of protein, such as collagen powder (I use the green tub great lakes powder; it dissolves great in coffee). I feel like that might put your test even more into an annals of science, and for us folks who don’t have the finger prick blood testers, it would be fun to know. Also, sugar free sweeteners like splenda (!!) or stevia–do they have any effect? Anyway–great read, exactly what I was looking for when I googled my question.
Alternate between days where you eat normally, and days where you take in fewer than 600 calories. Some participants will even go so far as to eliminate food altogether during the off days. Just remember to stay hydrated while fasting, and be aware of what your body is telling you. If you find yourself feeling faint (instead of just hungry) then this may not be the best option for you.
Autophagy is spring cleaning for your cells. It’s Latin for “self-eating,” which is spot-on: when autophagy turns on, your cells sift through their internal parts, get rid of anything that’s damaged or old, and install shiny new versions.[8] Autophagy is like a tune-up for your car: afterward everything runs more smoothly. It reduces inflammation and even boosts longevity. Intermittent fasting triggers, to quote researchers, “profound” autophagy, especially in your brain.[9]
Listen to your body during workouts. If you get light headed, make sure you are consuming enough water. If you notice a significant drop in performance, make sure you are eating enough calories (especially fats and protein) during your feasting window. And if you feel severely “off,” pause your workout. Give yourself permission to EASE into intermittent fasting and fasted workouts. This is especially true if you are an endurance athlete.
Please Note: The author of this site is not engaged in rendering professional advice or services to the individual reader. The ideas, procedures, and suggestions contained within this work are not intended as a substitute for consulting with your physician. All matters regarding your health require medical supervision. The author shall not be liable or responsible for any loss or damage allegedly arising from any information or suggestions within this blog. You, as a reader of this website, are totally and completely responsible for your own health and healthcare.
Is intermittent fasting safe? Remember that you’re only supposed to fast for twelve to sixteen hours and not for days at a time. You’ve still got plenty of time to enjoy a satisfying and healthy diet. Of course, some older women may need to eat frequently because of metabolic disorders or the instructions on prescriptions. In that case, you should discuss your eating habits with your medical provider before making any changes.
Eating all your meals in an 8-hour window (say, eating between noon and 8PM, and fasting the other 16 hours a day) causes significant weight loss without counting calories.[1]  While this type of intermittent fasting causes weight loss no matter what people eat, research shows that people who do it in a healthy manner lose twice as much weight (7% vs. 3% of their body weight) as those who fast while still eating junk. So it’s still important to follow a high-performance diet like the Bulletproof Diet while you fast.
So here’s the deal. There is some good scientific evidence suggesting that circadian rhythm fasting, when combined with a healthy diet and lifestyle, can be a particularly effective approach to weight loss, especially for people at risk for diabetes. (However, people with advanced diabetes or who are on medications for diabetes, people with a history of eating disorders like anorexia and bulimia, and pregnant or breastfeeding women should not attempt intermittent fasting unless under the close supervision of a physician who can monitor them.)

Now that you’re properly prepared, it’s time to get started with intermittent fasting keto. In addition to cutting carbs, increasing fat intake and restricting food consumption to a specific window of time each day, you should also be sure to stay hydrated and plan your workout routine around your fasting schedule. While exercising is okay during days that you fast, it’s important to listen to your body and avoid pushing yourself too hard.
I would like to know what led you to the conclusion to recommend eating in the morning and fasting in the evening instead of the other way around. You do not link any studies here that show TRF in the morning is better than TRF in the evening. You do state “Nighttime eating is well associated with a higher risk of obesity, as well as diabetes.” but I would hazard a guess that alot people that snack into the evening have many other factors at play that could effect their risk of obesity and diabetes and are possibly not fasting at all. I have been doing TRF from 12-8pm every day for almost a year and have seen vast improvements in my health, not least of which is a loss of 70 lbs, so it seems odd to read items 3 and 4 on your 4 ways to use this information for better health. If you have evidence that supports the idea that TRF in the evening is bad then I would like to see it and perhaps change my dieting habbits.
Harvard-trained physician and author of The Paleovedic Diet, Dr. Akil Palanisamy further explains to POPSUGAR that "autophagy is the self-cleaning process by which the body's cells break down and recycle damaged proteins and components. This is activated by intermittent fasting, but anything other than water (even black coffee) disrupts it to some extent."
Intermittent fasting is probably what you’d think. It’s fasting… intermittently. Or, to be a bit clearer, it’s skipping meals. But while missing a meal will certainly mean fewer calories throughout your day, the magic of intermittent fasting isn’t just in how it reduces food intake, but in how it helps your body make better use of the calories you keep.

The 5:2 diet, also known as the “Fast Diet,” involves restricting calories two days a week to 500 calories per day (with two 250 calorie meals), while eating normally for the other five days. For example, you might eat all of your regular meals Saturday through Wednesday, and eat 500 calories per day on Thursdays and Fridays.There isn’t a ton of research to back up this diet, although it was publicized by Michael Mosley, a British journalist and doctor. Since it doesn’t completely restrict food on the fasting days, it may also be an effective way to ease into fasting without shocking your system. The Fast Diet is considered safe for men and women.

The four-hour eating window — which Hofmekler refers to as the “overeating” phase — is at night in order to maximize the Parasympathetic Nervous System’s ability to help the body recuperate, promoting calm, relaxation and digestion, while also allowing the body to use the nutrients consumed for repair and growth. Eating at night may also help the body produce hormones and burn fat during the day, according to Hofmekler. During these four hours, the order in which you eat specific food groups matters, too. Hofmelker says to start with veggies, protein and fat. After finishing those groups, only if you are still hungry should you tack on some carbohydrates.
Please Note: The author of this site is not engaged in rendering professional advice or services to the individual reader. The ideas, procedures, and suggestions contained within this work are not intended as a substitute for consulting with your physician. All matters regarding your health require medical supervision. The author shall not be liable or responsible for any loss or damage allegedly arising from any information or suggestions within this blog. You, as a reader of this website, are totally and completely responsible for your own health and healthcare.

To make “down” days easier to stick to, Johnson recommends opting for meal replacement shakes. They’re fortified with essential nutrients and you can sip them throughout the day rather than split into small meals. However, meal replacement shakes should only be used during the first two weeks of the diet — after that, you should start eating real food on “down” days. The next day, eat like normal. Rinse and repeat! (Note: If working out is part of your routine, you may find it harder to hit the gym on the lower calorie days. It may be smart to keep any workouts on these days on the tamer side, or save sweat sessions for your normal calorie days.)
Forms of intermittent fasting exist in religious practices in various groups across the world.[12] Religious fasting regimens include, but are not limited to, Vrata in Hinduism, Ramadan fasting (Islam), Yom Kippur fasting (Judaism), Orthodox Christian fasting, Fast Sunday (The Church of Jesus Christ of Latter-day Saints), and Buddhist fasting.[12] Certain religious fasting practices, like Buddhist fasting, only require abstinence from certain foods, while others, like the Jewish fast on Yom Kippur, last for a short period of time and would cause negligible effects on the body.[12]
None of the coffee additives caused a significant drop in our blood ketone levels. At 120 minutes, my, (Becky’s), ketone readings increased after drinking black coffee, coffee with cream, coffee with MCT oil, and coffee with butter. At 120 minutes, Keith’s ketone readings dropped by 0.1 mmol/L after drinking only black coffee. His ketone readings rose slightly after consuming coffee with cream, MCT oil, and butter.

Even though this plan is advanced, it's very simple. Don't eat anything every other day. This is the most intense form of fasting but can produce amazing results. Every other day, eat healthy fats, clean meat sources, vegetables, and some fruit, and then on your fasting days, you can consume water, herbal tea, and moderate amounts of black coffee or tea.


This fasting process will not only activate autophagy in your cells, it will also increase your ketones much more quickly than if you were just eating a standard ketogenic diet. If you start implementing intermittent fasting and activities (like walking, cycling, or lifting weights) together, you can raise ketone levels and increase autophagy more than you would with intermittent fasting alone. This suggests that intermittent fasting would be a great addition to your life, but it is important to be familiar with the negative symptoms that can arise before you start.
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.
So here’s the deal. There is some good scientific evidence suggesting that circadian rhythm fasting, when combined with a healthy diet and lifestyle, can be a particularly effective approach to weight loss, especially for people at risk for diabetes. (However, people with advanced diabetes or who are on medications for diabetes, people with a history of eating disorders like anorexia and bulimia, and pregnant or breastfeeding women should not attempt intermittent fasting unless under the close supervision of a physician who can monitor them.)
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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