Is it endorphins that increase appetite after physical exercise? The debate was not settled, including on the reality of this “post-sport” hunger. Some will tell you that they are ravenous after a ten-minute walk, others have their appetite cut by an effort exceeding an hour.
- Endorphins are responsible for the feeling of happiness that comes from prolonged physical exertion.
- The results of various scientific studies support physical activity as an appetite suppressant, particularly through the modification of the food reward circuit.
- However, the impact of physical exercise on hunger also depends on each person’s personality, the quantity and repetitiveness of the effort.
The discovery of the role of endorphins in sport dates back to the 1980s. They are hormones secreted by the brain. The ending “orphine”, which recalls the word “morphine”, is not there by chance. Our body is in fact a large-scale “dealer”. Endorphins have a dual role: it is, above all, a painkiller.
Endorphins are addictive, but do they increase appetite?
Prolonged physical effort, which man’s adaptation to his environment has required, is done in a painful context, particularly for the muscles and joints. Endorphins are there to reduce its intensity. Since life has undoubtedly become more comfortable, at least in industrialized countries, it is the second role of these hormones that is now the most important. Endorphins participate in what is called the “reward circuit”. Like real morphine, which, by calming, creates an exceptional feeling of well-being, endorphins are responsible for the feeling of happiness caused by prolonged physical effort. In fact, it takes at least a good hour to start feeling its effects.
But, like morphine, they would induce a phenomenon of dependence! A high-level athlete easily tolerates pain during exercise, but intensive training can turn into a real drug addiction: overtrained athletes often have an irrepressible need to do sport, with a frequent escalation of the daily “dose”, to obtain the best secretion of this hormone.
Is it endorphins that increase appetite after physical exercise? The debate was not settled, including on the reality of this “post-sport” hunger.
Research has provided a scientific answer, thanks to MRI techniques. We know perfectly well the areas of the brain that control the pleasure of eating and manage the quantity necessary for the disappearance of the feeling of hunger. MRI allows us to “see” in the brain what is called the reward circuit. The results are in favor of physical activity, which limits appetite.
Exercise can curb cravings for fatty and sugary foods
It seems that physical exercise modifies the food reward circuit by reducing the quantity needed but, above all, by favoring less fatty, less rich foods.
The experiment consisted of taking two groups of volunteers. The first stayed in front of the television; the other was given an hour of physical activity. Then everyone was put in front of an “all you can eat” buffet. The inactive ones spontaneously went for foods rich in sugar and fat. The “athletes”, which was confirmed by the MRI study of their brain, saw their reactivity to food signals significantly reduced. The areas managing quantity and the reward circuit remained calm, even in front of desserts, while they woke up in the idlers! The only criticism that can be made of these results is that they only concern people of so-called “normal” weight. Studies on obese people are not as clear, probably because the mechanism of overconsumption in them is more complex and the sight of food increases the feeling of hunger tenfold, making physical exercise a very useful pretext.
However, if a few years ago scientists thought that everything was under the control of hormones, we now know, and this is important news, that the brain is sensitive to exercise and can in response change the hunger message by reducing it. The enemies of sport may come out with arguments like: “45 minutes of walking for a 70 kilo man represents an expenditure of approximately 300 kilocalories, the equivalent of a butter croissant with a little jam”, summarizing exercise as a simple reduction in caloric intake is reductive and only presents a very partial version of the interest of daily practice.
In conclusion, the impact of physical exercise on hunger depends on each person’s personality, the quantity and the repetitiveness of the effort.
