Late Meals Boost Hunger, Decrease Calories Burned, and Promote Fat Building: Study

Blood sugar. (Shutterstock)

In the United States alone, 42 percent of adults are affected by obesity, while an estimated 650 million adults are affected worldwide.

An obese adult is at higher risk of developing diabetes, cardiovascular disease, certain cancers, and COVID-19 morbidity. Historically, the recommendation for targeting obesity has been to reduce dietary intake and to increase physical exercise. However, the effects of these measures have been found to be only temporary.

In a new study published by Cell Metabolism, researchers from Brigham and Women’s Hospital found that late eating has an impact on the three players in body weight regulation and in turn, obesity risk: regulation of calorie intake, the number of calories burned, and molecular changes in fat tissue.

"We wanted to test the mechanisms that may explain why late eating increases obesity risk," said one of the leading researchers, Frank Scheer. "Previous research by us and others had shown that late eating is associated with increased obesity risk, increased body fat, and impaired weight loss success. We wanted to understand why."

Scheer added that when all other factors are kept consistent, eating just four hours later “makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat."

In the study, 16 patients with a body mass index (BMI) in the overweight or obese range each completed two separate routines: one with an early meal schedule, and the other with the same meals, each scheduled about four hours later in the day. Throughout the study, researchers took blood samples and fat tissues from participants. They also measured energy expenditure from the patients and had them document their hunger and appetite during the course of the study.

Results showed that eating late had a massive impact on hunger and appetite-regulating hormones, which control our drive to eat. Participants who ate later were found to burn calories at a slower rate and had fat tissues genetically switched to promoting fat tissue production and decreasing fat breakdown at the same time. The hormone leptin, which tells us when we’re full, also decreased in the 24 hours in the late eating group, compared to the early eating group.

While researchers controlled for confounding variables like caloric intake, physical activity, sleep, and light exposure in the study, Scheer said that, in reality, many of these factors may themselves be influenced by meal timing.

"In larger scale studies, where tight control of all these factors is not feasible, we must at least consider how other behavioral and environmental variables alter these biological pathways underlying obesity risk,” Scheer added.