You are probably wondering how there could possibly be a benefit to eating less frequently that goes beyond what you are already getting with a ketogenic diet. Restricting carbs and eating enough fat and protein does come with a plethora of health benefits, but when you add intermittent fasting to your lifestyle you can increase energy and reverse aging by harnessing the power of a nobel prize winning process.
IF as a weight loss approach has been around in various forms for ages, but was highly popularized in 2012 by BBC broadcast journalist Dr. Michael Mosley’s TV documentary Eat Fast, Live Longer and book The Fast Diet, followed by journalist Kate Harrison’s book The 5:2 Diet based on her own experience, and subsequently by Dr. Jason Fung’s 2016 bestseller The Obesity Code. IF generated a steady positive buzz as anecdotes of its effectiveness proliferated.
Conversely, a 2013 study completed by researchers at Washington University School of Medicine, presented the exact opposite, showing increased reactions in receptors on the tongue, when participants were given artificial sweeteners. Their study concluded that if the receptors are capable of detecting sweetness, even though calories aren’t present, a hormonal response (insulin release) is likely.
Based on this, researchers from the University of Alabama conducted a study with a small group of obese men with prediabetes. They compared a form of intermittent fasting called “early time-restricted feeding,” where all meals were fit into an early eight-hour period of the day (7 am to 3 pm), or spread out over 12 hours (between 7 am and 7 pm). Both groups maintained their weight (did not gain or lose) but after five weeks, the eight-hours group had dramatically lower insulin levels and significantly improved insulin sensitivity, as well as significantly lower blood pressure. The best part? The eight-hours group also had significantly decreased appetite. They weren’t starving.
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.
According to a study published in Translational Research in 2014, intermittent fasting can reduce your weight by 3 to 8 percent over three to 24 weeks. A systematic review published in Molecular and Cellular Endocrinology in 2015 confirmed these results by reporting that, on average, participants following a fasting diet lost between 7 and 11 pounds in 10 weeks.
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.
Of course, most people use IF with another weight-loss plan. For instance, you might decide to eat 1,200 calories a day to lose weight. You may find it much easier to spread out 1,200 calories within two meals and two snacks than in three meals and three snacks. If you’ve struggled with weight loss because your diet either didn’t work or was simply too hard to stick to, you might try intermittent fasting for quicker results.
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.

You’ll spike your blood sugar when you eat. If you’re fasting on a high-carb diet and you’ve powered through the cravings and lack of energy from low blood sugar, there’s a good chance you’ll eat a ton of carbs when you feast. You want to eat big meals when you fast to make sure you’re getting enough calories, but all those excess carbs in one go will spike your blood sugar in the opposite direction, from low to high.[14] High blood sugar causes fatigue and lack of focus. That raging hunger will also cause you to binge unnecessarily, and whatever carbs you don’t use will get stored as fat.
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.)
60 year old and just started IF a week ago. I eat from noon to 8pm. The noon start works for me because I’m not starting my day with the thought of food! I LOVE FOOD AND LOVE TO EAT! I am moving away from some bad habits and it doesn’t seem that difficult for me with IF! Just one week in and I do feel better. Can’t wait till I’ve got a month under my belt.
Intermittent fasting is hard in the contemplation, of that there is no doubt. “You go without food for 24 hours?” people would ask, incredulously when we explained what we were doing. “I could never do that.” But once started, it’s a snap. No worries about what and where to eat for one or two out of the three meals per day. It’s a great liberation. Your food expenditures plummet. And you’re not particularly hungry. … Although it’s tough to overcome the idea of going without food, once you begin the regimen, nothing could be easier.”
Fasting ramps up your stem cell production.[6] Stem cells are like biological playdough — your body turns them into any kind of cell it needs and uses them to replace old or damaged cells, keeping you younger on a cellular level. Stem cells are great for your skin, joints, old injuries, chronic pain, and more. You can try stem cell therapy…or you can just fast.
There are different types of intermittent fasting, but the most common involves only eating within a certain window of time each day. For example, you might only eat between 12pm and 6pm each day, giving you a 6-hour “feeding” window when you eat all of your calories for the day. That means you’ll be fasting for 18 hours in between. Your intermittent fasting ratio would then be 18/6.
Now if you're not used to drinking your coffee black, don't despair. There are some no-sugar options that can help lighten and sweeten your morning cup of joe. If you're like me and can't fathom the idea of drinking black coffee, consider adding a few splashes of unsweetened almond or coconut milk. Cutting out the sugar can be especially hard for some people, but there are sugar-free substitutes on the market, such as stevia, erythritol, or xylitol, that can serve as a great alternative. Another modification you can make in your coffee during IF is to consume bulletproof coffee. Simply by adding high-quality grass-fed butter and MCT oil, you may find yourself having a much easier time abstaining from food.
60 year old and just started IF a week ago. I eat from noon to 8pm. The noon start works for me because I’m not starting my day with the thought of food! I LOVE FOOD AND LOVE TO EAT! I am moving away from some bad habits and it doesn’t seem that difficult for me with IF! Just one week in and I do feel better. Can’t wait till I’ve got a month under my belt.

Perhaps most importantly, intermittent fasting is one of the simplest strategies we have for taking bad weight off while keeping good weight on because it requires very little behavior change. This is a very good thing because it means intermittent fasting falls into the category of “simple enough that you'll actually do it, but meaningful enough that it will actually make a difference.”


So how long does it take to go into ketosis when fasting? On a standard keto diet, it typically takes around 2–3 days to reach ketosis, although it can take up to seven days in some cases. However, many people find that keto adaptation intermittent fasting can speed up the process and help your body burn through glycogen stores more quickly to help enter ketosis.
Alternate-day fasting. Go back and forth between feasting days and fasting days. Eat like a king or queen one day, then eat nothing the next. This will probably be the most challenging fasting option for most people. If you try it, make sure you’re eating a ton on your feast days, otherwise you’ll fall into a major calorie deficit and you’ll likely feel miserable.
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.
Cons: Even though it’s nice to eat a few snacks rather than go without any food for 20-plus hours, the guidelines for what you need to eat (and when) can be hard to follow long-term. The strict schedule and meal plan may also interfere with social gatherings. Additionally, eating one main meal at night — while following strict guidelines of what to eat, and in what order — can be tough. It’s especially hard for those who prefer not to eat large meals late in the day.
Since all of your hormones are so deeply interconnected, when one hormone is thrown off balance, the rest are also negatively impacted. It’s like a domino effect. As the “messengers” that regulate nearly every function in your body — from energy production to digestion, metabolism, and blood pressure — you don’t want to disrupt their natural rhythm.
I’m 63 years old and I have been following a daily 19 hour protocol called Fast 5, fast5.org for two years. I eat lunch at 3pm and dinner at 7pm close my eating window at 8pm. I’ve lost 43 lbs and kept it off, feel great and I am no longer pre diabetic. I eat what I want and don’t track anything. I belong to a Facebook Intermittent fasting group called Fast Club and would to have you check it out. Fasting is free and it works!
Those studies above, in working with small sample sizes, and different types of fasting than recommended here, would lead me to believe that fasting affects men and women differently, and that many of the weight loss benefits associated with intermittent fasting (that affect insulin and glucose responses) work positively for men and negatively for women.
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