Time-restricted eating is not a magic bullet for metabolism.

This transcript has been edited for clarity.

welcome to impact factora weekly commentary on new medical research. I'm Dr. F. Perry Wilson of Yale School of Medicine.

One in three American adults, or about 100 million people in this country, have metabolic syndrome. I'm giving you the official criteria here, but essentially this is the syndrome: insulin resistance Visceral fat accumulation makes you more susceptible to many chronic diseases such as diabetes, heart disease, and even dementia.

Metabolic syndrome is basically a lifestyle-related disease. There is a direct relationship between our diets, the wide availability of carbohydrate-rich and highly processed foods, and the rise of this syndrome in the population.

It reminds me of something I learned from one of my epidemiology teachers. “Lifestyle-related diseases require lifestyle re-intervention.” But did you know? I don't really understand anymore.

I've seen multiple diets come and go with varying effects. I grew up in the low-fat era. This era was perhaps the most detrimental to the nation's health, as food manufacturers began replacing fat with carbohydrates, causing many of the problems we face today.

But I was also part of the Atkins diet and low-carb craze. All things being equal, it's a healthier approach. And I've seen these variants. The Paleo diet (basically a low-carbohydrate, high-protein diet with minimal processed foods) and the Mediterranean diet, which seeks to replace some of the fat with healthier fats.

And of course, there are time limits for eating.

Time-restricted eating, a type of intermittent fasting, has the advantage of being very simple. There are no cookbooks or recipes. Eat whatever you want, but limit it to certain times of the day, ideally within 10 hours from 8 a.m. to 6 p.m.

When it comes to weight loss, effective diets tend to work because they reduce calorie intake. I know, people will get anger In this regard, thermodynamics is not just a good idea, it is also a law.

But losing weight isn't the only reason you need to eat healthy. What we eat can affect our health in many ways. Certain foods have more benefits atherosclerosisincreases inflammation, increases strain on the kidneys and liver, and can affect glucose homeostasis.

So when I saw this article, I was very interested. ”Time-restricted eating in adults with metabolic syndromeAppears in “ Annual report of internal medicine This week we investigated the effects of time-restricted eating on metabolic syndrome itself. Can this lifestyle-related disease be cured with this lifestyle intervention?

In the study, 108 people, all of whom had metabolic syndrome but did not have full-blown diabetes, were randomly assigned to usual care (basically nutrition education) and time-restricted eating. In that group, participants were instructed to reduce their eating time by at least 4 hours to achieve an 8- to 10-hour eating time. The group was followed for 3 months.

Now, before we get to the results, it's important to remember that the success of lifestyle intervention trials is highly dependent on how well people adhere to the lifestyle intervention. Time-restricted eating isn't as simple as taking a pill once a day.

The researchers had participants track their intake using a smartphone app to see if they were adhering to a diet period.

Broadly speaking, they did. At baseline, the eating window for both groups was approximately 14 hours per day. Think 7 a.m. to 9 p.m. The intervention group cut that to just under 10 hours, leaving 10% of their days outside the target period.

A lifestyle change has been achieved. The main results are: Hemoglobin A1c At 3 months old. A1c integrates serum glucose over time and is therefore a good indicator of intervention success in terms of insulin resistance. However, to be honest, the effect was disappointing.

Specifically, the time-restricted eating group had a 0.1 percentage point greater change in A1c than the control group. On average, the baseline A1c of 5.87 went from a 3-month A1c of 5.75.

Other metabolic syndrome markers were similarly lackluster, with no differences in fasting blood glucose, mean blood glucose, or fasting insulin.

There was a slight change in weight. The control group that received the nutritional education lost 1.5% of their body weight over three months. The time-restricted eating group lost 3.3% more weight, or about 7 pounds. This is a reasonable number.

That weight loss resulted in small, but statistically significant, improvements in BMI, body fat percentage, and body fat percentage. LDL cholesterol.

Interestingly, and encouragingly, although the intermittent fasting group had greater weight loss, there was no difference in muscle mass loss.

In summary, we can say that, indeed, time-restricted eating seems to help you lose weight. This is essentially due to the fact that time-restricted eating results in lower calorie intake, as seen here.

But at the end of the day, this trial was about whether this relatively simple lifestyle intervention made a difference in terms of metabolic syndrome, and the data are not convincing to support that.

This graph shows how many of the five metabolic syndrome factors participants in this study had from start to finish. Over a three-month period, seven people in the time-restricted eating group moved from three criteria to two or one. In other words, you are “cured” of metabolic syndrome. Nine people in the standard group were cured according to that definition. Remember, they had to have at least three to have this syndrome and therefore be eligible for the trial.

So the question remains: There's nothing metabolically magical about time-restricted eating. If it simply leads to weight loss by forcing people to reduce their calorie intake, we need to acknowledge that there may be better ways to achieve the same goal. Ten years ago, I would have said that the only way to end the metabolic syndrome epidemic in this country was through lifestyle changes. Today, we live in a world of GLP-1 weight loss drugs. It's a completely different world now. Yes, it's expensive. Yes, there are side effects. But you need to compare and evaluate them. And for now, lifestyle changes alone don't compare at all.

F. Perry Wilson, MD, MSCE, is an associate professor of medicine and public health and director of the Clinical and Translational Research Accelerator at Yale University. His science communication work can be found on the Huffington Post, NPR, and here at Medscape. he tweets @fperrywilsonand his book, How drugs work and when they don't work, currently available.