Early bird, in fact, gets the worm. New research in animal models indicates that late-morning exercise is more effective in boosting metabolism and burning fat than an evening workout.
Researchers at Karolinska Institute and the University of Copenhagen examined adipose tissue, also known as body fat, of mice after a high-intensity exercise session performed late in the morning and another session late in the evening.
The researchers studied various markers for fat metabolism and analyzed which genes were active in adipose tissue after physical activity.
Exercising in the late morning was associated with a higher metabolic rate, as it increased the expression of genes involved in the breakdown of adipose tissue, thermogenesis (heat production), and mitochondria in the adipose tissue. 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 from the Department of Molecular Medicine and Surgery and the Department of Physiology and Pharmacology, Karolinska Institutet.
Further research is necessary to determine whether these findings apply to humans, the study authors say.
Research in humans from 2022 compared the effects of exercising early in the morning, between 6 a.m. and 8 a.m, and in the evening, between 6 p.m. and 8 p.m. Women working out in the morning saw their total body fat decrease an average of 3% more than those exercising in the evening.
The morning exercisers also had abdominal fat drop an average of 7% more than the evening group, and their blood pressure decreased significantly.
“Based on our findings, women interested in reducing belly fat and blood pressure, while at the same time increase leg muscle power should consider exercising in the morning. However, women interested in gaining upper body muscle strength, power and endurance, as well as improving overall mood state and food intake, evening exercise is the preferred choice,” said principal investigator Dr. Paul J Arciero, a professor at the Health and Human Physiological Sciences Department of Skidmore College.
For substantial health benefits, the U.S. Department of Health and Human Services Physical Activity Guidelines for Americans recommend at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic physical activity a week for adults.