To maximize the benefits of physical activity, even the time in which we practice it seems to be of considerable importance. In particular, doing physical activity in the morning burns more fat than when it is done in the evening. This is what emerges from a very recent scientific research published in the journal PNAS by a group of scientists from Karolinska Institutet, Sweden, and the University of Copenhagen, Denmark (Pendergrast et al, PNAS, Feb 2023).
The benefits of physical activity
A sedentary lifestyle and obesity are associated with an increased risk of developing type 2 diabetes, but also cardiovascular disease, cellular degeneration and depression. On the contrary, an active lifestyle with moderate physical activity improves insulin sensitivity and the use of glucose, favors the reduction of body fat, stimulates the metabolism and counteracts inflammation, with benefits for all organs. But is it possible that the time at which physical activity takes place can maximize its benefits? This question is legitimate since the biological processes within our body depend on the circadian rhythm, which is our internal biological clock. So is it possible that physical activity done when the body is awake and active, such as in the morning, could have a different impact than the physical activity in the evening, when the body begins to enter the resting phase? To answer this question and shed light on this fascinating topic, scientists have developed the research we are discussing today.
Physical activity, when it would be better to practice it, the study
The study was carried out in the laboratory on a population of mice, which are a model widely used to analyze the effects on humans. Indeed, mice and humans share most of the basic biological functions. The scientists thus studied what happens in mice after they have undergone a session of physical exercise at the beginning of the activity phase of their sleep-wake cycle, which corresponds to the morning for humans, and at the beginning of the resting phase, which corresponds to the evening for humans. What emerged is that physical activity carried out at the beginning of the activity phase, namely in the morning or even late morning for us humans, stimulated the activation of the genes involved in lipolysis, which is the process by which the body breaks down fats for energy. Not only that, thermogenesis, which is the production of heat, and the activity of the mitochondria, which are organelles responsible for producing energy for the cell, have also increased. This was only observed following physical activity at the beginning of the activity phase and was independent of food intake. The findings suggest that morning physical activity is more effective for humans than evening exercise in terms of metabolism acceleration and fat burning.
Practicing moderate physical activity is always a healthy choice, regardless of the time at which we do it. Brisk walking, jogging, swimming or cycling help fight inflammation, diabetes, cardiovascular disease and cellular degeneration. In the case of overweight and obesity, however, we now know that extra help can come from the time of physical activity. To get the maximum benefit and burn more fat, it may be useful to prefer the hours of the morning until late morning rather than the evening, in order to adapt the circadian rhythm.