Lose weight or gain muscle: The best time of day to reach your goal

New “Atlas of Exercise Metabolism”: Losing weight or building muscle: This is the best time of day to reach your goal

Exercise in the morning or in the evening – does it make a difference? Definitely. An international research team uses the “Atlas of Exercise Metabolism” to show when you should train to effectively achieve your goals.

It is now an undisputed fact that sport is important for staying healthy, fit and efficient in the long run. However, researchers have now found that physical exertion has different effects on our body, hormones and thus potential fat burning and muscle building depending on the time of day.

Using the so-called “Atlas of the movement metabolism”, which records the various phases of the human biorhythm, it should be possible in the future to create even more effective sports therapies for people with obesity and type 2 diabetes. But what exactly does this atlas mean? The results at a glance.

Sport has an impact on hormones, metabolism and well-being

While some do sports in the morning to start the day fit and full of energy, others use their evening training to balance a long day at work and to be able to switch off. “The most important thing is sports” one or the other may be thinking now. That in itself is true, but the training can be adapted even more effectively to personal goals – if you turn a lot of screws. At least that is what the study led by Helmholtz Munich and the Karolinska Institute in Sweden suggests. In a study with mice, they investigated how sport affects the organism depending on the time of day.

“This is the first study to describe metabolism as a function of exercise and time of day across multiple tissues. We now better understand how exercise can alter disrupted circadian rhythms associated with obesity and type 2 diabetes,” explains Dominik Lutter, who led the study for Helmholtz Munich and at both the Helmholtz Diabetes Center and the German Center for Diabetes Research (DZD) researcher. . “Our results will enable new studies exploring the proper timing of training for therapies and disease prevention.”

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The study focuses on health-promoting signals that have far-reaching effects on human health. They affect, for example, sleep, physical performance, memory and our metabolism.

Do you want to lose weight or build muscle?

To better understand the effects of the so-called circadian rhythm, the research team conducted a sports experiment with mice. The circadian rhythm is defined as a biological rhythm that lasts about 24 hours, during which almost all body cells regulate their biological processes.

Previous studies have already recognized that the health-promoting effects of the sport can be optimized if the movement is coordinated with the human circadian rhythm – because the sensitivity of different tissues changes during the day.

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“Atlas of kinetic metabolism” explains signaling molecules in the body

The mice trained either in the morning or in the evening. Blood and tissue samples from the brain, heart, muscles, liver and fat were constantly taken from them, using which the researchers recorded dozens of different metabolic products and hormone signaling molecules and recorded their changes depending on the time of day and training.

The created “Atlas of exercise metabolism” shows which signaling molecules are found in different tissues depending on the time of day after physical exertion: In the morning, the mice extracted their energy primarily from the body’s fat stores.

This is because the energy reserves in the liver are empty after the night’s fast. Normally, the body provides sugar supplies to the muscles when there is no glucose in the stomach and intestines. This is how the metabolism of the ketone body was activated during the morning training. It causes the body to use ketones instead of glucose as an energy source – and thus switch to fat metabolism earlier. In addition, cortisol levels, the so-called stress hormone, are at their highest in the morning, further promoting the breakdown of endogenous substances.

Weight loss: What speaks for sports in the morning

According to the researchers, anyone who wants to lose weight purposefully is best served with morning exercise on an empty stomach. Another study from the University of Bath shows that fasting exercise can also improve the body’s ability to respond to insulin – and thus inhibit insulin resistance. This can reduce the risk of diabetes.

A study from the University of North Carolina provides another argument for people who want to lose weight to exercise in the morning: Exercise in the morning should effectively alleviate the feeling of hunger.

Muscle building: What speaks for sports in the evening

If, on the other hand, you want to actively build muscle, you should postpone your training until the afternoon or evening. By eating all day, the body has enough energy available that it can provide quickly and in high doses during exercise. In particular, strength athletes are dependent on food or liver glucose. As the liver’s glucose stores are only completely filled up in the late afternoon or early evening, the optimal training effect is only achieved then. The body is able to push itself to its individual limits.

In addition, studies show that humans – due to the body’s biorhythm – most often only gain strength, mobility and endurance during the day. The body has on average 20 percent more strength than in the morning.

Last but not least, the hormone level also has an impact on the success of the evening workout. As body temperature and the level of numerous messenger substances – including the male sex hormone testosterone – tend to be higher, muscle growth is specifically promoted. Due to the increased body temperature, the muscles are more flexible and less susceptible to injury.

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Background for the meaningfulness of the study

As this is a mouse study, the results cannot be extrapolated to humans. It should also be noted that different forms of training such as endurance, strength or high intensity were not taken into account in the studies – the mice only ran on the treadmill and trained their endurance in this way. Significant factors such as gender, age and any previous illnesses must therefore be included in the assessment. In particular, hormone levels in men and women show significant differences and can thus lead to different training effects and body reactions.

Last but not least, the study itself emphasizes that in humans, nutrition is another major influencing factor on the physical processes during morning and evening exercise, which can be investigated further in further studies.

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