Scientists have discovered a new molecule produced in high quantities after strenuous physical activity (but not after walking). The hypothesis that it is capable of reducing appetite
Those who train often ask themselves the question: why do you feel hungry after certain exercises and not at all after others? In particular after high-intensity work the desire to eat seems to disappearyet one would expect the opposite. The relationship between fitness and appetite has been debated for years and a study published in the journal Nature has tried to investigate the link. According to American and Danish researchers, the answer must be sought in one particular new molecule identified inThe blood flow of mice, racehorses and humans is much higher after strenuous physical activity compared to other milder ones.
It is well known, and everyone may have proved it, that immediately after high intensity exercise, particularly of the aerobic type, one does not feel hungry while, conversely, a mild exercise such as a walk can lead to an appetite, says Gianfranco Beltrami, vice president of the Italian Sports Medicine Federation. However, the temporary effect – warns the specialist – and the mechanism linked to a delicate hormonal balance: numerous studies have documented the drop in grelin
aa hormone produced by the fundus of the stomach and pancreas cells that stimulates appetite and a contemporary increase in a peptide produced by the mucous membrane of the intestinal cells, which instead reduces the appetite. And that also comes into play leptin another protein that increases the sense of satiety. However, the hormonal alterations described are also linked to diets and sleep habits. So the scientists wondered if there was something more specific affecting hunger after exercise.
Esercizi sul treadmill
To figure this out, the researchers placed mice on small treadmills and made them run at increasing speeds, untilexhaustion. Before and after the activity they took blood from the rodents and compared it with levels of thousands of other molecules found in the bloodstream, discovering a new molecule, a mix of lactate, an enzyme produced by the body after intense physical effort and phenylalanine, a amino acid, created in response to the high levels of lactate released during exercise. The new molecule was named lac-phe. To clarify whether lac-phe actually affects theappetite the researchers administered the molecule to obese mice, which typically eat heartily. Their consumption of kibble decreased by more than 30%. Apparently the mice were less hungry with an extra dose of lac-phe. As a counter test, mice capable of producing only minimal amounts of lac-phe were bred and ran on treadmills five times a week for some time. After each run the animals were given the opportunity to eat as many high-fat kibble as they wanted. Running usually helps mice avoid weight gain even if they are on a high-calorie diet. But the animals capable of producing only a little lac-phe got puffed up, ate more kibble, gaining about 25% of the weight compared to the control group. Without this molecule, the same exercise drove the mice to consume excess food.
Research on men
Finally, the same researchers were able to identify the new molecule also in racehorses after an intense gallop and in eight healthy young men who performed three different types of exercises on different days: they cycled slowly for 90 minutes, lifted weights, performed running sprints followed by weight training. Lac-phe has always been produced, but in very small quantities after prolonged exercise. In conclusion, the more intense the physical activity, the more lac-phe was produced and, at least in the mice, appetite seemed to decrease.
The study, while presenting very interesting insights, has some limitations. It is difficult to establish which proteins actually increase the sense of satiety and the concentration of all the other substances already known should be evaluated to evaluate the effects of the new molecule, comments Beltrami. The research does not explain how lac-phe might interact with brain cells to affect appetite, however the mechanism may be evolutionary, the authors speculate. If you’re running away from a threatening animal, the autonomic nervous system quickly tells the brain to stop digestion or any other unnecessary process. It is also unknown how strenuous the exercise would have to be to produce enough of the molecule to stave off hunger, and it is unclear how long the effects would persist. Finally, the male athletes were all healthy: it is not known whether lac-phe is also produced by overweight people.
December 3, 2022 (change December 3, 2022 | 15:08)
© breaking latest news