Turns out you’re not just what you eat. You’re when you eat. Because a new study in mice suggests that, in the battle of the bulge, the timing of meals influences the piling on of pounds.

In the experiment, researchers gave groups of mice either standard feed or a high-fat diet for 100 days. Some ate at random intervals, day and night. Others were restricted to feeding only during eight-hour windows in every 24-hour period.

Mice on the high-fat but time-restricted diet gained less weight and suffered less liver damage than the mice who ate around the clock. And they had improved nutrient utilization and glucose tolerance, among other markers of metabolic health. Both groups ate the same food in the same amounts, so the only difference was the timing. The study was published in the journal Cell Metabolism. [Megumi Hatori et al., "Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet"]

The researchers say when mice eat regularly all day and night, it throws off their metabolic cycles. Like if we don’t sleep well, we don’t function as well cognitively during the day. They suggest the same may be true for human metabolism. Which means that when we eat could play a role in controlling obesity.

—Cynthia Graber