But the research also raises the question of whether eating less is really what you want from Thanksgiving and exercise.
Exercise intensity affects appetite
The effects of exercise on appetite are powerful but strange. Exercise requires energy. Appetite helps supply it by encouraging eating. So it makes intuitive sense that exercise makes you hungry. And in many cases, yes.in many the studyPeople who exercise moderately, for example by walking, are thirsty afterwards and ready to nod.
But not when they push themselves. Most people “don’t feel hungry after a hard workout,” Long said.
But why and how? Long, a scientist and avid runner, suspected that molecules circulating in the bloodstream after exercise might be involved. These molecules probably travel to the brain and other organs, where they activate processes that drive or dampen hunger.
To find out, he and more than 20 colleagues looked deep inside mice before and after they sprinted on a small treadmill.for study Scientists published in Nature this summer used a process called mass spectrometry to enumerate every molecular-level change involved in metabolism in the bloodstream of post-exercise animals.
they found a lot. But after the animals ran, one in particular jumped out in large numbers. It was an obscure molecule that scientists had never named or typed before. Upon examining the chemical composition of the molecule, researchers discovered that it is a mixture of lactic acid, a substance abundantly produced by cells during strenuous exercise, and phenylalanine, an amino acid. Scientists named it lacquer, and from the data they noticed that mice excreted more lactate during exercise, meaning that the harder they ran, the more lacquer appeared in their blood.
Molecules that dampen post-exercise appetite
Next, they set out to see if lacquer affected hunger, injecting it into sluggish mice that normally enjoyed a meal. “We cut the amount in half,” Long said. and the animals then stuffed themselves. Without the molecule, strenuous exercise stimulated appetite.
Finally, they checked for increases in lacquer in the bloodstream after gentle bike riding, weight lifting, or sprinting at high-intensity intervals. It turned out to produce rakufe,” Long said.
In other words, vigorous exercise produced more appetite-suppressing molecules than lighter exercise.
The study sparked a scientific stir and prompted some commentators to speculate other paper That lacquer was eventually refined for use as a medicinal product, and could blunt people’s appetites without the need for hard training first.
Exercise won’t help you “earn” food
However, most exercise scientists believe that exercise’s effects on hunger go far beyond the action of a single molecule. Studies have shown that it has a profound effect on hormones.In general, moderate or light activity increases levels of a hormone specifically called acetylated ghrelin (or simply ghrelin) that makes you want to eat more.
According to Tom Hazel, Professor of Kinesiology at Wilfried Laurier University in Waterloo, Ontario, who has extensively studied exercise and eating behaviour.
In a new, as-yet-unpublished study from his lab, he found that nine middle-aged participants experienced a significant drop in ghrelin levels almost immediately after a workout that repeated vigorous 15-second sprint intervals. said. The results mirror previous results for his group. work, We also found that ghrelin dropped sharply immediately after a hard workout and remained low for as long as two hours.
Interestingly, people’s ghrelin levels in several studies in his group were tracked inversely to blood lactate levels, similar to the lac-phe study. ghrelin tends to decrease, and hunger can be suppressed.
Similarly, various processes and parts of other bodies are involved in exercise and appetite, including our brain.in modern animals the studyFor example, strenuous exercise temporarily altered the firing of specialized neurons dedicated to hunger, increased activity in neurons that appear to reduce appetite, and increased activity in other neurons that suppress hunger. rice field. This process has not yet been seen in humans.
It also remains a mystery how all these systems and processes interact, and whether they differ between males and females, young and old, heavy and slim, or mice and us. .
Perhaps most fundamentally, “It’s a bad idea to think of exercise as a way to ‘earn’ food,” says Glenn Gaither, an exercise physiology professor at Arizona State University who studies physical activity and weight management.
For one thing, exercise burns very few calories. “In one of our studies, he had subjects eat two donuts,” he said, adding up to 520 calories. “It took less than five minutes to consume the donuts, but over an hour to burn them down.”
More importantly, just like the Thanksgiving buffet, exercise has immeasurable rewards, and weaponizing one to keep the other from digging can dull the joy of both. There is
Still, if you want to join your Turkey Day workout and burn a little less, go for the Activestrength training It’s like high-intensity interval training,” Hazel says.
Have a fitness question? e-mail [email protected] I may answer your question in a future column.
