Physical Activity at Different Times of the Day Can Affect the Body in Different Ways

Physical activity at the right time of the day seems able to increase fat metabolism, at least in mice. 

Physical activity at different times of the day can affect the body in different ways since the biological processes depend on the circadian rhythms of the cells. To ascertain how, researchers studied the adipose tissue of mice after a session of high-intensity exercise performed at two points of the daily cycle, an early active phase and early rest phase (corresponding to a late morning and late evening session, respectively, in humans). The researchers studied various markers for fat metabolism and analysed which genes were active in adipose tissue after exercise.

The researchers found that physical activity at an early active phase increased the expression of genes involved in the breakdown of adipose tissue, indicating a higher metabolic rate. These effects were independent of food intake.

“Our results suggest that late morning exercise could be more effective than late evening exercise in terms of boosting the metabolism and the burning of fat, and if this is the case, they could prove of value to people who are overweight,” says Professor Juleen R. Zierath.

“The right timing seems to be important to the body’s energy balance and to improving the health benefits of exercise, but more studies are needed to draw any reliable conclusions about the relevance of our findings to humans,” says Professor Zierath.


Logan A. Pendergrast, Leonidas S. Lundell, Amy M. Ehrlich, Stephen P. Ashcroft, Milena Schönke, Astrid L. Basse, Anna Krook, Jonas T. Treebak, Lucile Dollet, Juleen R. Zierath. Time of day determines postexercise metabolism in mouse adipose tissue. Proceedings of the National Academy of Sciences, 2023; 120 (8) DOI: 10.1073/pnas.2218510120

Karolinska Institutet. “Time of day may determine the amount of fat burned by exercise.” ScienceDaily. ScienceDaily, 13 February 2023. <>.

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