Every diet plan that has ever produced results is, at its heart, a strategy for lowering calorie intake. All-fat, no-fat, reduced-carbs, gluten-free, paleo… they may all take different approaches to weight loss, but they all have the same result. By limiting food intake, or even just limiting food options, these diets reduce our calorie consumption. And when calorie intake drops below calorie burn, that’s when we start to drop the pounds.
Most people make an IF schedule that requires them to fast for 12 to 16 hours a day. During the rest of the time, they eat normal meals and snacks. Sticking to this eating window isn’t as hard at it sounds because most people sleep for about eight of their fasting hours. In addition you’re encouraged to enjoy zero-calorie drinks, like water, tea, and coffee.
Both the keto diet and intermittent fasting trigger something referred to as autophagy. The latter is simply the technical term for a natural bodily function called “self-eating.” Although at first this may sound a bit frightening, autophagy is merely your body’s normal detoxification process, during which it eliminates contaminants and replaces them with newly formed, healthy cells.
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.)
While some nutrition experts contend that IF only works because it helps people naturally limit food intake, others disagree. They believe that intermittent fasting results are better than typical meal schedules with the same amount of calories and other nutrients. Studies have even suggested that abstaining from food for several hours a day does more than just limit the amount of calories you consume.

Although some of the intermittent fasting methods online seem more intense than others (some can last upwards of 48 hours), the beauty of intermittent fasting is that you get to choose and experiment with how long you fast. This not only allows you to determine how intermittent fasting can fit in within your lifestyle, but to discover the fasting sweet spot that helps you feel best physically.
Hello Maria, I can honestly say I look forward to my morning black coffee now, just as much as I enjoy a cup with a little cream, once my eating window opens late afternoon. My easiest “go-to” tip is adding just the smallest pinch of pink Himalayan salt to my coffee. It really works to smooth out the black coffee bitterness! Good luck with your IF journey, Maria!

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.”
Jerimiah, the linked study in the article (https://www.sciencedirect.com/science/article/pii/S1550413118302535) specifically studied “eTRF”(Early Time-Restricted Feeding) from 8am – 2pm, and implies that eating earlier is better than later. I haven’t read the study (it’s behind a damn Elsevier pay-wall), so I don’t know how strongly they feel about early vs late, though. For me, personally, 12-8 is doable, and skipping dinner (given the existence of a family and the desire to have dinner with said family) isn’t doable, so I’m pleased to hear from you and April above that it’s working. Just starting!
Once you start your IF journey, you’ll most likely find that you feel fuller longer and can keep the meals you do eat very simple. There are a few different ways you can fast, so I broke up each of the different plans below into beginner, intermediate, and advanced along with a typical meal plan for each day. The combination of nutrients will give you the energy you need to enhance the benefits of your fasting journey. Just make sure to take into account any individual food intolerances, and use this as a guide for your particular health case, and adjust from there.
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.)

Stable blood sugar levels are vital to the success of any diet. This is because when glucose levels plummet, it leads to intense hunger, which almost always results in binge eating. Stable blood sugar levels help eliminate headaches, lack of focus, poor memory, and brain fog as well. Interestingly, these are common complaints among those who follow high carbohydrate diets, as opposed to diets that are rich in fat and protein.
I am a 65-year-old male who started IF seven weeks ago. I only eat between noon and 8pm. I am obese, but losing about a pound a week so far. Notably, except for time, I have not changed what I eat at all. My diet was never terrible or great, and now it is the same, a mix of raw fruit sometimes and a donut another time. But I only eat it during the appointed hours. Remarkably, I do not feel hungry. I used to eat comfort breakfasts like pancakes or waffles, and I thought I would miss them. But no, I truly am not hungry in the mornings. I often delay lunch, but I still stop eating at 8. That alone probably has cut many calories of desserts. Bottom line: works for me so far.

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.”


Crescendo fasting only requires you to fast a few days a week instead of every day. My experience is that women get a lot more benefit from doing it this way without accidentally throwing their hormones into frenzy. This is a more gentle approach that helps the body more easily adapt to fasting. And if women do it right, it can be an amazing way to shave off body fat, improve inflammatory markers and gain energy. (7)

On the flip side of that, eating keto can make your periods of fasting more manageable. For example, someone who is eating a diet higher in carbs will likely have more discomfort with intermittent fasting as the body constantly switches between glucose for fuel and ketones for fuel. By continuing to eat keto even during feeding periods, you can keep your body constantly running on ketones.

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.
Black coffee won't break your fast or take you out of ketosis. In fact, according to a report published in the Journal of Basic and Clinical Physiology and Pharmacology in 2017, caffeine may even increase your metabolism, which will help promote weight loss. Black coffee also helps curb your appetite, which can make getting through your morning fast much more manageable.

That’s what I suggest you do when you start fasting. It should happen naturally, and you shouldn’t have to force it. If you’re still a sugar burner instead of a fat burner, it’s going to be much harder…so if you’re serious about trying out this whole fasting thing, I suggest slowly transitioning to a high-fat low-carb diet. You can read about the benefits here.

Islam is the only major religion that engages in a fasting practice reflective of intermittent fasting in terms of both food consumption and diet consistency.[12] The duration of the Ramadan fast is between 28 and 30 days, depending on the year, and consists of not eating or drinking from sunrise until sunset.[12] During the holiday, Muslims eat twice per day: once in the morning before dawn and once in the evening after dusk.[12] A meta-analysis on the health of Muslims during Ramadan shows significant weight loss during the fasting period of up to 1.51 kilograms (3.3 lb), but this weight was regained within about two weeks of Ramadan ending.[13] The analysis concluded that "Ramadan provides an opportunity to lose weight, but structured and consistent lifestyle modifications are necessary to achieve lasting weight loss."[13] Negative effects of Ramadan fasting include increased risk of hypoglycemia in diabetics as well as inadequate levels of certain nutrients.[12]

As far back as the 1930s, scientists have been exploring the benefits of reducing calories by skipping meals. During that time, one American scientist found that significantly reducing calories helped mice live longer, healthier lives. More recently, researches have found the same in fruit flies, roundworms and monkeys. Studies have also shown that decreasing calorie consumption by 30 to 40 percent (regardless of how it’s done) can extend life span by a third or more. Plus, there’s data to suggest that limiting food intake may reduce the risk of many common diseases. Some believe fasting may also increase the body’s responsiveness to insulin, which regulates blood sugar and helps control hunger.
Another perk? There are no “forbidden foods,” and no counting calories, weighing food or restricting your diet, which makes it a bit easier to follow. That said, this isn’t a free-for-all. “You still have to eat like a grown-up,” Pilon says. It’s all about moderation: You can still eat whatever you want, but maybe not as much of it. (A slice of birthday cake is OK, he says, but the whole cake isn’t.)
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.
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