A morning workout could hack your circadian rhythm and boost metabolism, science says

Taking high intensity exercise in the morning may help to boost the metabolism and burn more body fat, mice study suggests.

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Published: February 13, 2023 at 8:00 pm

Got a stubborn few pounds that you are struggling to shift? Move your workout to late morning.

Working out in the morning rather than the evening could help to burn more body fat, a study in mice carried out by researchers from the Karolinska Institutet in Sweden and the University of Copenhagen in Denmark has found.

Many biological processes going on within our bodies vary according to our circadian rhythm – the 24-hour cycle that is part of the body’s internal clock. To test how this affects the body’s ability to burn fat, the team had groups of mice undergo sessions of high-intensity exercise at one of two points of their daily cycle - an early active phase and an early rest phase. This corresponded to a late morning session and a late evening session in humans.

The team found that exercising earlier in the day increased the expression of mice's genes involved with the breakdown of body fat and boosted their metabolic rates. This meant that the mice not only burned more body fat during the morning workouts but also continued to burn more calories throughout the rest of the day.

”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,” said Prof Juleen Zierath from the Department of Molecular Medicine and Surgery and the Department of Physiology and Pharmacology, Karolinska Institutet.

As mice and humans share many physiological features, the finding suggests that a similar effect may be seen in humans, the researchers say. However, there are several key differences, such as the fact that mice are nocturnal, so further research is needed to firm up the link between exercise time and fat loss in humans.

”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,” said Zierath.

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