Exercising in the morning can burn more fat than at other times of the day, new research suggests.
Biological processes work differently depending on the time of day, due to each cell’s circadian rhythm – the natural cycle of changes in our body over each 24-hour period.
A new study by researchers at Sweden’s Karolinska Institute and the University of Copenhagen found that mice who exercise in an early active phase of their daily cycle have a higher fat metabolism than in an early resting phase.
This suggests that people may see more fat when working out late in the morning, rather than late in the evening, according to the scientists.
“Our findings suggest that late morning exercise may be more effective than late evening exercise in terms of boosting metabolism and fat burning, and if so, may be of value to people who too heavy,” said Professor Juleen. Zierath, of the Karolinska Institute.
The scientists set mice on high-intensity exercise at two points a day, and studied the effect on their fat tissue, otherwise known as body fat.
They looked at the genes that were active in white tissue, and found that those involved in boosting metabolism were more abundant in the morning slot – regardless of how much food the mice ate.
The researchers found that the earlier exercise increased the expression of genes involved in breaking down fat through heat and producing mitochondria – indicating a higher metabolic rate.
“Right timing appears to be important for the body’s energy balance and for enhancing the health benefits of exercise, but further studies are needed to draw any reliable conclusions about the relevance of our findings to humans,” said Professor Zierath.
Mice are a well-established model for studying human physiology and metabolism.
However, the researchers say that their comparison, published in the Proceedings of the National Academy of Sciences magazine, limited by the fact that mice are nocturnal.
Previous studies have suggested that working out early in the morning on an empty stomach can help speed up weight loss and increase energy levels.
Exercising early in the morning, when insulin levels are lower after an overnight fast, is thought to prompt the body to tap into its fat reserves for fuel rather than focusing on recently ingested calories.
Additional reporting from the SWNS