Circadian Rhythm Influences How Many Calories Your Body Burns After Eating: Study

Researchers have found that the body's internal biological clock directly influences how many calories are burned after eating, helping explain why meal timing may play an important role in weight management. The study, published in Metabolism, showed that diet-induced thermogenesis (DIT)—the energy the body uses to digest, absorb, and process food—follows a natural circadian rhythm that peaks in the biological morning and reaches its lowest point in the biological evening.

Previous research has suggested that people who eat later in the day may be more likely to gain weight. Scientists had also observed that DIT tends to be higher in the morning than in the evening, but it was unclear whether this difference was driven by daily behaviors such as sleep, activity levels, and light exposure, or by the body's internal clock itself.

To answer this question, researchers used a highly controlled method known as the Constant Routine protocol. This approach minimizes the influence of environmental and behavioral factors, allowing scientists to isolate the effects of the body's circadian system. Participants remained under carefully controlled conditions while researchers measured metabolic responses after eating.

The results revealed a clear circadian pattern in DIT. Calorie burning after meals was highest in the biological morning, around 7 a.m. for the participants, and lowest in the biological evening, around 7 p.m. This finding suggests that the body's internal clock naturally supports greater energy expenditure earlier in the day.

The researchers believe these findings provide a biological explanation for why late eating may contribute to weight gain or make weight loss more difficult. By showing that meal-related calorie burning varies according to circadian timing, the study supports the idea that consuming a larger proportion of daily calories earlier in the day could improve energy balance.

The findings may help guide future meal-timing recommendations aimed at supporting metabolic health, weight management, and long-term disease prevention.

REFERENCE: Vujović, N., et al. (2026) Constant-routine protocol reveals an endogenous circadian rhythm in diet-induced thermogenesis with a peak in the biological morning. Metabolism. DOI: 10.1016/j.metabol.2026.156655. https://www.metabolismjournal.com/article/S0026-0495(26)00165-4/abstract