How Helpful Is Early Time-Restricted Eating?

We are not done with the notion of time-restricted eating. Two new studies tell us that it might be helpful. One is specifically about weight loss with early time restricted eating. The other is a simple test of the metabolic effects of limiting the window for eating to ten hours in the day – all before 6:00 p.m.

Though these two studies each show the potential for benefits, the net benefit of early time-restricted eating remains an open question.

Metabolic Benefits: A Ten-Hour Limit

The first study was a crossover study. That means a group of 14 adults with type 2 diabetes each tried each of the study’s two eating patterns for three weeks. They followed one pattern for three weeks and then switched to the other. The order was random. Some started with ten-hour window for eating their usual meals. Others started with a 14-hour window. On either schedule, they were asked to eat whatever they typically ate in a day. The difference was the length of time over which they spread their eating. Plus, for the ten-hour eating schedule, the study required them to finish eating by 6:00 p.m.

The researchers, led by Charlotte Andriessen, found that the shorter, earlier window for eating resulted in better control of blood sugar. It did not, however, produce any improvement in insulin sensitivity or glycogen levels in the liver.

Weight Loss with Early Time-Restricted Eating

The newest study suggests that limiting a person’s eating pattern to no more than eight hours per day and finishing with it by 3:00 p.m. can produce a real benefit for weight loss. This was an RCT of 90 adults with obesity lasting 14 weeks. The window for eating in the control group was an average of 12.3 hours, while it was 7.6 hours for the early time-restricted eating group. So that nets out to a restriction of 4.8 hours per day.

Both groups were on the same calorie-restricted diets for weight loss and both groups lost weight. But people in the early time-restricted eating group lost about 50 percent more weight than the control group. That meant they lost about five pounds more of their starting weight.

Different Studies, Different Results

That new study from the University of Alabama at Birmingham (UAB) stands in contrast to a similar but slightly different study from Guangzhou, China. The Guangzhou study asked people to limit their eating pattern to eight hours per day versus their baseline pattern of eating over a bit more than ten hours per day. So in the Guangzhou study, the time restriction was not so great as in the UAB study. And thus, the Guangzhou study produced no discernable difference in weight loss.

So what are we to think about time-restricted eating? The simplest take away might be that we have more to learn. It seems likely that time restricted eating – just like any well-studied dietary strategy – might be helpful for some people and not for others. Many dietitians will add that getting your bigger meals earlier in the day is often beneficial.

Eating is a complex behavior and a very different experience for every one of us. If you want to find a healthier pattern for your eating, your best bet is to work with a smart dietitian who can find a strategy that works for you. This is the very essence of personalized nutrition.

Click here for the Andriessen study, here for the UAB study, and here for an invited commentary on it. For more on the Guangzhou study, click here, here, and here.

Ascet, painting by Pablo Picasso / WikiArt

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August 9, 2022