How meal timing may reduce obesity and improve metabolic health

Scientists have revealed a mechanism behind why eating late at night can be linked to weight gain and metabolic disease in a study in mice. The connection between meal timing, sleep, and obesity is well-known, but poorly understood. Research shows that eating during inactive periods (at night for people and during the day for nocturnal mice) can disrupt the body’s internal molecular “clock,” leading to an impairment of numerous physiological processes across the day/night cycle, including energy (calorie) intake and energy expenditure. This mistimed feeding can also alter fat tissue and contribute to weight gain. Understanding how meal timing affects metabolism could help the development of interventions for obesity.

To explore the reasons behind mistimed feeding and weight gain, researchers fed male mice a high-fat diet either exclusively during their inactive or their active period. Within 1 week, mice fed during their inactive period gained more weight and experienced decreased energy expenditure compared to those fed only in the active period, replicating what has been previously shown. This result led the team to investigate whether fat tissue metabolism differed based on the meal timing. Using mice that were genetically altered to have enhanced thermogenesis—or heat released by fat cells burning calories—they found that the mice fed during the inactive period did not gain weight and had improved glucose (sugar) tolerance, a measure of metabolic health, compared to mice without enhanced thermogenesis fed the same food during the same time of day, suggesting that thermogenesis protects against weight gain resulting from inactive period meals. Next, they sought to determine the specific metabolic underpinnings of this protection and identified the molecule creatine, which the body stores to use as energy, as the likely metabolic mechanism through which restricting feeding to the active period improves health. Indeed, genetic disruption of creatine synthesis in fat cells reduced the metabolic benefits of feeding restricted to the active period.

Taken together, these results expand upon our knowledge of the mechanisms that underlie the benefits of restricting eating to active periods. Time-restricted feeding in people is a promising approach to decrease body weight and improve metabolic health with few side effects. However, given that many people are unable to maintain this schedule for reasons including shiftwork, sleep loss, and the social aspect that people tend to dine in the evening, more research could help inform the design of behavioral and therapeutic interventions.