New York — Why are we so annoying after some workouts and not interested in eating after others?
In a new study published in Nature on June 15, an international team of scientists suggests that the answer is partly due to the action of a single molecule produced after exercise to slow down hunger. .. Molecules in the bloodstream of mice, humans, and racehorses appeared much larger than simple exercise after strenuous exercise. This suggests that strenuous exercise may be the key to controlling subsequent dietary intake.
The relationship between fitness and diet is a well-known thorn. Studies show that people who start exercising without controlling their calorie intake usually lose weight and gain weight over time.
Many factors affect the outcome, including someone’s current fitness, weight, diet, gender, genetics, metabolic rate, and even the timing of exercise. Some experiments (but not all) suggest that a morning session can burn more fat than the same exercise later in the day.
Appetite is also important. If you feel greedy in the hours after training, you may burn more calories than you burned. But what caused us to feel hungry after we exercised was a bit of a mystery. For decades, scientists have encouraged various substances, such as the hormones leptin and ghrelin, to move to the brain and become more or less interested in eating.
Studies show that exercise changes levels of these substances, but it also changes diet and sleep habits. Some researchers have begun to suspect that there may be some exercise-specific reactions that affect appetite.
As a result, scientists at Stanford University School of Medicine, Baylor College of Medicine, and the University of Copenhagen have used newly developed technologies to look for molecules that appear more often in the bloodstream after exercise. They started with mice and placed them on a small treadmill to run at increasing speeds until they were exhausted. They collected blood before and after and compared the levels of thousands of molecules in rodent blood.
One stands out and is more than any other molecule. Although previously pointed out in several studies of metabolism and exercise, its chemical and biological role remained unclear. Scientists have discovered that this new molecule, a mixture of lactic acid and the amino acid phenylalanine, was clearly produced in response to high levels of lactic acid released during exercise. Scientists have named it lac-phe.
Researchers speculated that lac-phe might be related to post-exercise energy balance. This is because blood and other cells that produce lac-phe are widely involved in energy intake and body weight. Maybe they thought it would affect their appetite. To find out, they gave obese mice a kind of lac-phe. However, their kibble intake was reduced by more than 30 percent. They were obviously less hungry with extra lac-phe.
After that, the researchers returned to the movement. They raised mice that produced very little lac-phe and did their best on the treadmill five times a week for several weeks. After each run, the animals were allowed as many high-fat kibbles as they wanted. Running usually helps mice stop weight gain, even on high-calorie diets. However, the animals were unable to inflate many lac-phes, ate more kibbles, and gained about 25 percent more weight than the control group.
Lac-phe seems to have been the key to how strenuous exercise helped avoid weight gain in mice. Without it, the same exercise would have been overeating.
Finally, the researchers checked the lac-phe of other moving creatures. They first found it in the bloodstream of racehorses at a much higher level than before after a hard run. Next, we asked eight healthy young men to exercise three times. One time I cycled at a leisurely pace for 90 minutes, another time I lifted the weights, and the third time I did several 30-second sprints on an exercise bike.
Blood levels of lac-phe peaked after each type of exercise, but peaked after the sprint, followed by weight training. Gentle exercise for long periods of time was the least.
In other words, the more intense the exercise, the more lac-phe was produced, and at least in mice, more appetite appeared to be reduced.
“The results are fascinating and add a new dimension to our thinking about exercise and weight regulation,” said a professor of biochemistry at the University of Washington, Seattle, in neurobiology of behavior, which was not part of it. Expert Dr. Richard Palmiter said. Of new research.
“Always that the current menu of molecules that appear to regulate appetite and food intake, such as leptin and ghrelin, is incomplete and that this new metabolite / signaling molecule is a potentially significant addition to that list. I knew, “says Dr. Barry. Brown is an executive director of the Human Performance Clinical Research Lab at Colorado State University, Fort Collins, studying exercise and weight management. He was not involved in new research.
Assuming this process works like a mouse, the discovery of lac-phe provides a useful lesson. Dr. Jonathan Z. Long, a professor of pathology at Stanford University School of Medicine and senior author of the new study, said that if you want to avoid binging after training, you may need to increase your intensity.
He added that this idea has intuitive and evolutionary implications. “When sprinting from rhinos and other threats, the autonomic nervous system yells at the brain to shut down digestion and other unwanted processes.”
However, in his study, how lac-phe interacts with brain cells to affect appetite, how intense exercise is required for goose lac-phe formation, and the effects of molecules. I don’t know how long it will last. Also, the human activist was a healthy young man. That is, I don’t know if lac-phe exists or works the same for everyone else.
Still, if you want to reduce your hunger after exercising, you may want to increase your pace. Throw on some hills or sprint on the corners of distant streets during your next walk. “Data show that intensity is important” for exercise and appetite control, Dr. Long said.
This article was originally published in The New York Times.
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