Are there benefits to giving yourself a longer daily break from eating?
The reason many blood tests are done after an overnight fast is that meals can throw our system out of balance, raising certain biomarkers for disease, such as sugars, insulin, cholesterol and triglycerides. However, as you can see in the chart below and at 0:20 in my video Time-restricted diet Testfewer than one in ten Americans can even I make, I do it’s 12 hours without food. As evolutionarily unnatural as it is to eat three meals a day, most of us eat even more than that. A study used a smartphone app to record more than 25,000 food events and found that people tended to eat about every three hours for an average of about 15 hours a day. Could it be beneficial to give our bodies a longer break?
Time-restricted feeding is “defined as fasting for periods of at least 12 hours but less than 24 hours’, and this includes effort restrict caloric intake over a set period of time, usually ranging from 3 to 4 hours, 7 to 9 hours, or 10 to 12 hours per day, which results in a daily fast lasting 12 to 21 hours. When the mice are confined in a daily feeding window, they gain less weight even when fed the same amount as “ad-lib access” mice. Rodents I have Such high metabolisms, however, that a day of fasting can starve up to 15 percent of their lean body mass. This makes it difficult to extrapolation from mouse models. You don’t know what happens to people until you try it.
Certainly dropout rates in time-restricted feeding trials appear lower than most extended forms of intermittent fasting, suggesting it is more easily tolerated, but does it work? Researchers were found that when people stopped eating from 7:00 p.m. to 6:00 a.m. for two weeks, they lost about a pound each week compared to no time restriction. Note that “there were no additional instructions or recommendations regarding the amount or type of food eaten,” no gadgets, calorie counting, or record keeping. They simply told the study participants to limit their food intake to the hours of 6:00 AM. and 7:00 p.m., a simple intervention that is easy to understand and put into practice.
The next logical step? Try it for months instead of weeks. Obese men and women were asked to limit eating to the eight-hour window between 10:00 A.M. and 6:00 p.m. Twelve weeks later, they had lost nearly seven pounds, as you can see in the chart below and at 2:18 in my video. This deceptively simple intervention can work from many different angles. People not only tend to I eat more food later in the day, but I eat higher fat foods later in the day. With eliminating eating late at night removes the couch snack, a high-risk period for overeating. And, indeed, during the study with no food after 7:00 p.m., subjects accidentally ate about 250 fewer calories per day. Then there are the chronobiological benefits of avoiding eating late at night.
I did a whole series of videos on the role of our circadian rhythms I have in the obesity epidemic, how the timing of meals can to be critical and how we can race timing meals to our body clocks. To give you a taste: Did you know that calories are eaten at dinner are significantly more fattening than the same number of calories consumed at breakfast? See the table below and at 3:08 in my video. 
Calories is consumed in the morning cause less weight gain than the same calories consumed in the evening. A diet with a longer breakfast causes more weight loss from the exact same diet with a bigger dinner as you can see in the chart below and at 3:21 in my videoand evening snacks is more fattening than the same snacks if eaten during the day. Thanks to our circadian, metabolic rhythms decelerationhunger, carbohydrate intolerance, triglycerides and tendency to gain weight is all things that go bump in the night.
What about the fasting component of time-restricted feeding? There is already the dual benefit of taking in fewer calories and avoiding eating at night. Does it matter if you fast for 11 or 16 hours a day, considering the average person can only go about 9 hours a day without eating? How would you design an experiment to test this? What if you randomized people into two groups and had both groups eat the same number of calories per day and also eat late at night, but one group fasted even longer, for 20 hours? That’s exactly what researchers at the USDA and the National Institute on Aging did.
They were men and women randomized eat three meals a day or fit all those same calories into a four-hour window between 5:00 p.m. and 9:00 p.m., then fast the rest of the day. If the weight loss benefits from the other two time-restricted feeding studies were due to passive calorie restriction or avoidance of late-night eating, then presumably both of these groups should end up the same because they both eat the same quantity and they both eat slowly. That didn’t happen, though. As you can see below and at 4:49 in mine videoafter eight weeks, the time-restricted feeding group it is done with less body fat, almost five pounds less. They took in about the same number of calories, but lost more weight.
As shown below and at 5:00 on mine videoa similar study with an eight-hour eating window resulted in another three pounds of fat loss. So there seems to be something that gives your body daily breaks from eating around the clock.
Because this four-hour eating window in the study was at night, however, the participants suffered the chronobiological consequences—significant increases in blood pressure and cholesterol levels—despite weight loss, as you can see below and at 5:13 in my video. It was the best of both worlds turned out in 2018: early time-limited feeding, eating with a narrow window earlier in the day, which I covered in my video The benefits of early limited nutrition.
Isn’t that what’s confusing about the circadian rhythm? Morning calories count less and are healthier than evening calories. So, if you’re going to skip a meal to extend your daily fasting window, skip dinner instead of breakfast.
If you missed any of the other videos in this fasting series, check out the related videos below.
