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Time Restricted Eating Study Result Surprises Weight Loss Experts

Timothy Boyer Ph.D.'s picture
When you eat may not really matter when it comes to losing weight.

Eating breakfast like a King is an oft-repeated dieting advice that promotes eating your biggest meal early in the day. So what happens if you carry it further by eating almost all of your daily calories before the work day is even half over? Here are what some weight loss experts discovered that surprised even them.

New Study Supports Eat Breakfast Like a King Adage


According to an American Heart Association Scientific Sessions 2020 news release, a study that addresses whether time-restricted eating really works toward weight loss put it to the test by comparing two dieting groups who differed only in the time of the day they consumed their daily allotted number of calories.

This study comes in light of continual interest—and confusion—over whether choosing your meal times with an eye toward some variation of intermittent fasting, is a dieting method that may work for some dieters.

Choosing Your Fasting Diet Time Limit

In a relatively recent study published in the journal JAMA Internal Medicine, a 12-week study comparing a consistent meal timing (CMT) group against a time-restricted eating (TRE) group was determined to show no statistically significant differences in weight loss between the two groups. However, not all weight loss experts were convinced that the data was analyzed correctly to merit the conclusion that when you eat does not matter.

New Study Saying Time-Restricted Eating Doesn’t Work, Raises Skepticism

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In the American Heart Association Scientific Sessions referenced study, the researchers designed their experiment so that there would be no question as to the number of calories consumed when comparing meal consumption time differences.

“We have wondered for a long time if when one eats during the day affects the way the body uses and stores energy,” said study author Nisa M. Maruthur, M.D., M.H.S., associate professor of medicine, epidemiology and nursing at Johns Hopkins University in Baltimore. “Most prior studies have not controlled the number of calories, so it wasn’t clear if people who ate earlier just ate fewer calories. In this study, the only thing we changed was the time of day of eating.”

According to the news release the study was performed as follows:

Maruthur and colleagues followed 41 overweight adults in a 12-week study. Most participants (90%) were Black women with prediabetes or diabetes, and average age of 59 years. Twenty-one of the adults followed a time-restricted eating pattern, limiting eating to specific hours of the day and ate 80% of their calories before 1 p.m. The remaining 20 participants ate at usual times during a 12-hour window, consuming half of their daily calories after 5 p.m. for the entire 12 weeks. All participants consumed the same pre-prepared, healthy meals provided for the study. Weight and blood pressure were measured at the beginning of the study; then at 4 weeks, 8 weeks and 12 weeks.

Weight Loss Results from the Study

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What the study showed was that the participants in both groups lost weight and had decreased blood pressure—regardless of when their calories were consumed.

“We thought that the time-restricted group would lose more weight,” Maruthur said. “Yet that didn’t happen. We did not see any difference in weight loss for those who ate most of their calories earlier versus later in the day. We did not see any effects [differences between the two groups] on blood pressure either.”

The significance of the study is that it supports the common sense dieting advice that when it comes to losing weight, counting your calories remains the primary rule to follow for successful weight loss.

Counting Calories in Your Café Latte

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Another significance of the study is that it is also examining the effect of time-restricted meal consumption with respect to blood sugar, insulin and other hormones that could be affecting blood pressure and thereby our heart health. The researchers stated that they will perform follow-up studies focused on collecting more detailed information on blood pressure recorded over 24-hour time periods.

“Together, these findings will help us to more fully understand the effects of time-restricted eating on cardiometabolic health,” Maruthur said.

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Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Today, with an eye on the latest news, Timothy continues writing about science with a focus on what you need to know for healthier living. For continual updates about health, you can also follow Timothy on Twitter at TimBoyerWrites.

Image Source: Courtesy of Harald Funken from Pixabay


Calories by the clock? Squeezing most of your calories in early doesn’t impact weight loss” American Heart Association newsroom 9 Nov. 2020.

P805 - The Effect of Time-restricted Feeding on Weight: A Randomized Feeding Trial” Nisa Maruthur et al. American Heart Association Scientific Sessions Nov. 2020.