Time of day may determine how much fat you can burn in exercise

Credit: Alora Griffiths / Unsplash

In a study from Karolinska Institutet in Sweden and elsewhere, scientists found physical activity at the right time of the day seems able to increase fat metabolism, at least in mice.

They found that mice that did exercise in an early active phase, which corresponds to morning exercise in humans, increased their metabolism more than mice that did exercise at a time when they usually rest.

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 the time of day at which exercise is done affects the burning of fat, researchers studied the body fat of mice after a session of high-intensity exercise performed at two points of the daily cycle.

The two points included an early active phase and an early rest phase, corresponding to late morning and late evening sessions, respectively, in humans.

The researchers examined various markers for fat metabolism and analyzed which genes were active in adipose tissue after exercise.

They found that physical activity at an early active phase increased the expression of genes involved in the breakdown of adipose tissue, thermogenesis (heat production) and mitochondria in the adipose tissue, indicating a higher metabolic rate.

These effects were found only in mice that exercised in the early active phase and were independent of food intake.

These 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.

Mice and humans share many basic physiological functions, and mice are a well-established model for human physiology and metabolism.

However, there are also important differences, such as the fact that mice are nocturnal.

The team says the right timing seems to be important to the body’s energy balance and to improve the health benefits of exercise.

But more studies are needed to draw any reliable conclusions about the relevance of our findings to humans.

If you care about weight management, please read studies about diets that could boost your gut health and weight loss, and 10 small changes you can make today to prevent weight gain.

For more information about weight loss, please read studies that avocado could help you lose weight and belly fat, and a keto diet for weight loss can cause flu-like symptoms.

The study was conducted by Professor Juleen R. Zierath et al and published in the journal PNAS.

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