Changes in circadian and obesity-related gene expression were responsible.

During the past decade, several studies have shown an association between late mealtimes and obesity. In a new study from Brigham and Women’s Hospital in Boston, researchers examined possible mechanisms behind this phenomenon.

Sixteen overweight or obese young adults agreed to have their meals and physical activity controlled by the study protocol for several months. During the ‘early-meal’ study period, participants ate meals at about 9 a.m., 1 p.m. and 5 p.m., whereas in the ‘late-meal’ period, they ate at about 1 p.m., 5 p.m. and 9 p.m. Importantly, the total amount of calories and physical activity during the two study periods was identical; only the mealtimes were different.

Late eating had the following effects: it decreased levels of the appetite-reducing hormone leptin and greatly increased hunger; it increased storage of fatty acids and decreased burning of fatty acids in adipocytes; and it decreased waketime energy expenditure. Changes in the expression of genes involved in cellular circadian rhythms and genes known to control the storage and burning of fatty acids were clearly responsible.

Comment: Our cells have circadian rhythms that can alter biological processes within cells according to the time of day. Therefore, the results of this study are plausible. They also could be very important, if moving toward earlier mealtimes helped to deal with the growing global burden of obesity.

ANTHONY L. KOMAROFF, MD
Professor of Medicine, Harvard Medical School, Boston, USA.

Vujović N, et al. Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity. Cell Metab 2022; 34: 1486-1498.

This summary is taken from the following Journal Watch title: General Medicine