The study found no benefit to restricting the diet to some time of day

The idea of ​​losing weight is very attractive: reduce your food intake for six to eight hours every day, during which you can get what you want.

Studies in mice seem to support so-called time-restricted eating, a common form of intermittent fasting. Small studies in people with obesity have suggested that it may help lose pounds.

But now, strict One year study When the subjects followed a reduced-calorie diet between 8 a.m. and 4 p.m. or consumed the same number of calories at any time during the day, they found no effect.

“There is no point in eating in a narrow window,” said Dr. Ethan Weiss, a diet researcher at the University of California, San Francisco.

The study, published in the New England Journal of Medicine, was led by researchers at Southern Medical University in Guangzhou, China, and included 139 obese people. Women eat 1,200 to 1,500 calories per day, and men consume 1,500 to 1,800 calories per day. To ensure compliance, participants were asked to photograph each portion of the food they ate and to keep a food diary.

Both groups lost weight — an average of 14 to 18 pounds — but there was no significant difference in the amounts of weight lost in any of the diet strategies. There are also no statistically significant differences between the two groups in the measurements of waist circumference, body fat and lean body mass.

Nor did the scientists find any differences in risk factors such as blood glucose levels, insulin sensitivity, blood lipids, or blood pressure. Dr. Weiss and colleagues conclude, “These findings indicate that calorie restriction explained most of the beneficial effects observed with the time-restricted eating regimen.”

The new study was not the first to test time-restricted eating, but previous studies were mostly smaller, of shorter duration and without control groups. This research tended to conclude that people lost weight by only eating within a limited amount of time during the day.

Dr. Weiss used to be a true believer in time-restricted eating, and said he only ate for seven years between noon and eight in the evening.

in a previous searchHe and his colleagues asked some of the 116 participants to eat three meals a day, with snacks if they felt hungry, and the others were instructed to eat whatever they wanted between noon and 8 p.m. Participants lost a small amount of weight—an average of 2 pounds in the time-restricted eating group, and 1.5 pounds in the control group, a difference that was not statistically significant.

Dr. Weiss said he could hardly believe the results. He asked the statisticians to analyze the data four times, until they told him that more work wouldn’t change the results. “You have been faithful,” he said. “This was a difficult thing to accept.”

That experiment only lasted 12 weeks. Now, it appears that even a one-year study has failed to find a benefit in time-restricted eating.

Dr. Christopher Gardner, director of nutrition studies at the Stanford Center for Prevention Research, said he wouldn’t be surprised if time-restricted eating sometimes worked.

“Almost every type of diet available works for some people,” he said. “But what this new research supports is that when subjected to a properly designed and conducted study – a scientific investigation – it is no more beneficial than simply reducing daily caloric intake for weight loss and health factors.”

Weight-loss experts have said that time-restricted diets are unlikely to go away. “We don’t have a clear answer yet” about whether the strategy helps people lose weight, said Dr. Courtney Peterson, a researcher at the University of Alabama at Birmingham who studies time-restricted eating.

She suspects that the diet may benefit people by limiting the number of calories they can eat each day. “We just need to do larger studies,” Dr. Peterson said.

According to his experience, some people who have problems with a calorie-counting system do better if they are simply told to eat only during limited periods of time each day. “While this approach has not been shown to be better, it does not appear to be worse” than counting calories, he said. “It gives patients more options for success.”

The hypothesis behind time-restricted eating is that circadian genes that are thought to increase metabolism are turned on during daylight hours, says Dr. Caroline Apovian, associate director of the Center for Weight Management and Wellness at Brigham and Women’s Hospital in Boston. “If you eat less during daylight hours, would you be able to burn those calories rather than store them?” she added. Dr. Abovian said she would like to see a study comparing a group of people who eat excessively throughout the day to a group of time-restrictive eaters who also binge eat.

She said she still recommends patients eat time-restricted food, even though “we have no evidence.”

As for Dr. Weiss, he said he was convinced by his own study and said the new data reinforced his conviction that time-restricted eating offers no benefit. He said, “I started eating breakfast.” “My family says I’m much nicer.” – This article originally appeared in The New York Times

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