Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Time-restricted feeding, where you try to squeeze the same amount of eating into a narrow evening window, has benefits compared to eating in the evening and earlier in the day—but also has adverse effects, because you’re eating so much so late.

The best of both worlds was demonstrated in 2018—time-restricted feeding into a narrow window earlier in the day. Individuals randomized to eat the same food, but just in an 8 a.m. to 3 p.m. eating window, experienced a drop in blood pressures, oxidative stress, and insulin resistance— even when all the study subjects were maintained at the same weight. Same food, same weight, but with different results. The drops in blood pressures were extraordinary: from 123/82 down to 112/72 in five weeks—comparable to the effectiveness of potent blood-pressure drugs.

The longest study to date on time-restricted feeding only lasted 16 weeks: a pilot study with no control group that only involved eight people. But the results are still worth noting. Overweight individuals who, like most of us, were eating more than 14 hours a day, were instructed to stick to a consistent 10- to 12-hour feeding window of their own choosing. On average, they were able to successfully reduce their daily eating duration by about 4.5 hours, and within 16 weeks they had lost seven pounds. They also reported feeling more energetic, and sleeping better. This may help explain why all participants voluntarily expressed their interest in continuing the time-restricted feeding on their own, even after the study ended. You don’t often see that after weight loss studies. Even more remarkably, eight months later, they retained their weight loss and improved energy and sleep. At the one-year point, maintained their boosted energy and sleep, and kept the weight off, all from one of the simplest of interventions: just telling people to stick to a consistent 10- to 12-hour feeding window of their own choosing

How did it work? Even though they weren’t told to change nutrition quality or quantity, they appeared to unintentionally eat hundreds of fewer calories a day. With self-selected time frames, you wouldn’t necessarily think to expect circadian benefits, but because subjects were asked to keep the eating window consistent throughout the week, “metabolic jetlag could be minimized.” The thinking is that because people tend to start their days later on weekends, that’s disrupting their circadian rhythm. And, indeed, it is like they flew a few time zones west on Friday evening and flew back east on Monday morning. So, some of the metabolic advantage may have been due to maintaining a more regular eating schedule.

Early or midday time-restricted feeding may have other benefits as well. Prolonged nightly fasting with reduced evening food intake has been associated with lower levels of inflammation and better blood sugar control, both of which might be expected to lower the risk of diseases such as breast cancer. So, data was collected on thousands of breast cancer survivors to see if nightly fasting duration made a difference. Those who couldn’t go more than 13 hours every night without eating had a 36 percent higher risk of cancer recurrence. These findings have led to the suggestion that efforts to “avoid eating after 8 pm and fast for 13 hours or more overnight may be a beneficial consideration for those patients looking to decrease cancer risk and recurrence,” though we’d need a randomized controlled trial to know for sure.

Early time-restricted feeding may even play a role in the health of perhaps the longest living population in the world, the Seventh-Day Adventist Blue Zone in California. Slim, vegetarian, nut-eating, exercising, non-smoking Adventists live about a decade longer than the general population. Their greater life expectancy has been ascribed to these healthy lifestyle behaviors, but there’s one lesser known component that also may be playing a role. Historically, eating two large meals a day, breakfast and lunch, with a prolonged overnight fast was a part of Adventist teachings. Today, only about 1 in 10 Adventists surveyed were eating just two meals a day, but most—over 60 percent—reported breakfast or lunch was their largest meal of the day. Though this has yet to be studied with respect to longevity, front-loading one’s calories earlier in the day with a prolonged nightly fast has been associated with significant weight loss over time, leading the researchers to conclude that eating breakfast and lunch five to six hours apart, and making the overnight fast last 18 to 19 hours may be a useful practical strategy for weight control. The weight may be worth the wait.

Please consider volunteering to help out on the site.



Please enter your comment!
Please enter your name here