Researchers from Oregon Health and Science University in the United States explored how body weight influences daily energy use. Their findings suggest that individuals with a healthy weight tend to burn more calories during daylight hours, while those with obesity show higher energy expenditure at night. The results appeared in a peer reviewed journal focused on obesity and metabolic health.
In the study, thirty adults participated, including individuals with and without obesity. They spent six days inside a clock controlled circadian research facility where daily schedules shifted to alter wake and sleep times. The protocol kept participants awake and asleep at varying hours to examine how circadian rhythms shape energy use across a 24 hour cycle.
During the experiment, volunteers were awakened at the end of their allotted rest period and given time to eat, undergo blood tests, and take part in a range of assessments. A key component involved training with a special mask linked to an indirect calorimeter, a device used to measure energy expenditure by monitoring gas exchange.
Indirect calorimetry estimates metabolic rate by tracking airflow and the levels of oxygen consumed and carbon dioxide produced. From these measurements, researchers can determine the basal metabolic rate, the baseline energy requirement for sustaining life at complete rest. This method provides a window into how the body uses energy under controlled conditions and over the course of the day and night.
Results indicated that individuals with a healthy body weight tended to burn more calories during daylight. In contrast, those with obesity showed rising insulin levels as the day progressed, a sign that the body was actively managing glucose uptake. The same group also exhibited greater energy expenditure during the night, suggesting complex interactions between circadian timing and metabolic regulation in obesity.
While the exact mechanisms behind these patterns are still under investigation, scientists note that altered energy use across the day could be connected to how obesity develops or persists. It is not yet clear whether reduced daytime energy expenditure contributes to weight gain or arises as a consequence of obesity itself.
These findings may help inform weight management strategies and emphasize the importance of aligning daily activities with circadian biology. They also highlight the potential value of personalized approaches that consider how an individual’s weight interacts with their internal clock and energy needs over 24 hours.