Time-restricted eating without calorie counting was as effective as a calorie restriction diet for weight loss and cardiometabolic risk reduction in obese adults, according to findings published in Annals of Internal Medicine.
More than 40 percent of U.S. adults are clinically obese and obesity disproportionately affects individuals from underrepresented groups, according to recent data from the Centers for Disease Control and Prevention.
Weight management strategies can help reduce the risk of developing long-term health issues, including heart disease, stroke and type 2 diabetes. These strategies include calorie restriction diets and more recently, time-restricted eating, which involves only eating during a specified time frame. However, few studies have compared the efficacy of these strategies, which for many individuals can be difficult to maintain.
“People tend to burn out on those calorie counting strategies after a few months. Compared to calorie restriction, time-restricted eating is simple because you’re only keeping track of the clock. This could mean that time-restricted eating is an easier diet to stick to compared to calorie counting,” said Shaina Alexandria, PhD, assistant professor of Preventive Medicine in the Division of Biostatistics and a co-author of the study.
In the current study, the investigators aimed to determine whether time-restricted eating was more or less effective for weight loss and reducing cardiometabolic risk compared to a calorie restriction diet or no weight management strategy at all.
For 12 months, 90 adults who were clinically obese were randomly assigned to an eight-hour time-restricted diet (eating exclusively between 12 p.m. and 8 p.m. without calorie counting), a calorie restriction diet (involving a reduction in daily caloric intake by 25 percent based on weight), or no dietary intervention (control group).
“The literature has shown that people who are doing these types of diets tend to adhere to them more or tend to enjoy them more when they’re still able to enjoy dinner time with their friends and families, so the window of noon to eight was chosen so that people could still live their social lives and have dinner with their friends and families. After the first six months, participants transitioned into a weight maintenance phase where rather than an eight-hour window, participants were allowed to eat during a 10-hour window,” Alexandria said.
Of the participants, 46 percent were Hispanic, 33 percent were Black and 21 percent were white. Participants were asked not to change their amount of daily physical activity during the study period.
At the end of the study period, the investigators found that time-restricted eating for weight loss was as effective as calorie restricting. Participants in the time-restricted group also demonstrated a similar reduction in energy intake compared to the calorie restriction group and also lost 10 pounds more than the control group.
“The average reduction in energy intake was 425 calories in the time-restricted eating group and 405 calories in the calorie restriction group, which reaffirms that time-restricted eating is a natural calorie restriction technique. The weight loss seen in the time-restricted eating group was similar to the weight loss seen in the calorie restriction group, which also indicates that time-restricted eating might be as effective for weight loss as the classic calorie restriction strategy,” Alexandria said.
Participants in the time-restricted eating group also had larger reductions in their waist circumference and body fat mass compared to control participants, as well as an increase in insulin sensitivity.
“Whether time restricted eating could be an effective strategy for weight loss and glycemic control in people who are overweight or obese and have diabetes is worth exploring. We’ll be studying that next,” Alexandria said.
Krista Varady, PhD, professor of Kinesiology and Nutrition at the University of Illinois Chicago, was senior author of the study.
This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.