- New research indicates there’s no significant difference in weight loss between time-restricted diets and other diets.
- Experts interviewed by Healthline say there’s still plenty of merit to restricting eating to certain hours of the day.
- They say there’s no one-size-fits-all approach to weight loss and healthy living, and time-restricted eating works well for some people to control unnecessary eating.
- For weight loss and healthy living, the age-old advice still applies: Stick to mostly plant-based, unprocessed foods, don’t overeat, and drink lots of water.
New research shows that one common weight loss strategy — time-restricted eating — isn’t more effective than eating throughout the day.
A team of researchers from the University of California San Francisco and other institutions released their findings last week.
For their study, they created two groups comprising 116 participants.
One group ate 3 structured meals per day, while the other ate nothing between 8 p.m. and noon the following day.
“Time-restricted eating, in the absence of other interventions, is not more effective in weight loss than eating throughout the day,” the researchers wrote.
Despite the study’s conclusions, experts interviewed by Healthline say there’s more than meets the eye when it comes to time-restricted diets and individualized weight loss.
Not so clear-cut
Dr. Jamie Kane, chief of the section of obesity medicine and director of the Center for Weight Management at Northwell Health in New York, told Healthline that the study’s findings aren’t necessarily in line with what he and his colleagues have observed in practice.
“In our practice, and with a lot of my colleagues, time-restricted eating has worked out,” Kane said.
“When you’re dealing with these controlled trials, how you set up your controls can be very important,” he said. “So when I read it, I was a little bit disappointed, and then I saw that there are some issues involved that might elucidate why we’ve had some success whereas this study didn’t.”
Kane explained that many people respond particularly well to time-restricted eating.
“We recommend not going beyond 12 hours of eating in a day,” he said. “If someone’s not really willing to make wholesale dietary changes, we try to get them to at least time-restrict. There may be metabolic benefit based on animal models — we’re not sure. But at the very least, you’re not going to overeat.”
Dr. Minisha Sood, an endocrinologist with Northwell Health who is affiliated with Lenox Hill Hospital in New York, told Healthline that the study didn’t record or report the macronutrient composition or caloric intake of the two groups, which makes it difficult to draw definite conclusions.
“The baseline metabolic conditions of the cohorts should also be clearly delineated,” she noted. “Also surprising to me, to some degree, is that the patients following time-restricted eating lost more lean muscle mass than is usually lost with other weight loss methods. We don’t know if this is due to lower protein intake or another factor.”
Time-restricted eating 101
Healthline spoke to Michelle MacDonald, a registered dietitian/nutritionist and clinical dietitian supervisor at National Jewish Health in Denver, Colorado.
She said that time-restricted eating can work well for some people.
“There is no one-size-fits-all approach for weight loss — or health for that matter — if you’re trying to improve metabolic parameters,” she explained.
MacDonald said that the clear parameters of time-restricted eating can curb the binges that often contribute to an unhealthy lifestyle.
“Many patients tell me that they tend to eat a lot at night mindlessly, go for long periods of the day because they’re too busy, and then forage from late afternoon into the evening,” she said. “This is a pattern that is very common in people that I counsel. If there’s a rule that they can’t eat after a certain time, and they’re happy adopting it, it can be an easier pill to swallow than being told what to do.”
“Just getting people to get on board in a way that they’re happy with, and they don’t feel miserable and deprived about, is important. I think mindset is huge,” MacDonald added.
Kane said time-restricted eating is often recommended for people with issues with their circadian rhythms — for example, those who work nights or have irregular work schedules.
“If you eat at night and don’t sleep at night, then you become very insulin resistant, in addition to other hormones that govern appetite and energy use, they all get kind of flipped,” he said. “So we say, ‘OK, we can’t change the fact that you’re working all night, but let’s just eat for 6 to 8 hours during the day.’ It can help regulate your rhythms.”
“We have no evidence, hormonally, what’s happening, but it seems to work better than just eating willy-nilly, whenever you want,” Kane added.
Kane did caution that, while time-restricted eating can yield results, it doesn’t mean that the hours when someone is eating can be a free-for-all.
“If you’re just eating from 12 to 8, and otherwise restricting your eating, don’t expect miracles. If you’re eating two burgers and donuts and ice cream, foods that we know cause metabolic and inflammatory damage and weight gain, don’t expect to lose extensive weight,” he pointed out.
While time-restricted eating can help with weight loss, there are some basic tips that can lead to a healthier lifestyle — whether you’re restricting eating times or not.
“It’s not any particular diet in terms of low-carb or low-fat,” said MacDonald. “It has to do with whether a person can stick to it. So this kind of goes along with why you have to individualize your plan. You kind of have to suss that out. Ideally, the person knows themselves well enough to know whether or not a given approach is going to work.”
Sood said a helpful benchmark is to use the 80/20 rule. Essentially, 80 percent of the time, try to stick to your health goals, leaving the other 20 percent for deviations from those goals.
“Aim for no caloric intake within 3 hours of bedtime, choose a plant-rich diet low in processed foods, refined flours, and sugar,” she recommended.
“Stop eating at meals when you’ve reached about a 6 or 7 (out of 10) on your hunger scale. If you’re doing time-restricted eating, be mindful to keep protein intake intact and invest time in resistance training. Drink plenty of water and sleep at least 7 to 9 hours per night,” Sood said.
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