Jonathan Z. Long, a professor of pathology at Stanford University, said the study has practical implications if you want to avoid overeating on Thanksgiving, whether you should “do the turkey trot” or break out in a sweat. “This suggests that we may need to start making quick moves first,” he said. A medical doctor who studies the effects of exercise and hunger on cells.
Exercise intensity affects appetite
The effects of exercise on appetite are powerful, but strange. Exercise requires energy. Appetite helps feed it by eating. So it makes intuitive sense that exercise makes you hungry. And often it is.among many the studyPeople who exercise moderately, such as by walking, end up getting hungry quickly.
But not when you push yourself. Most people “do not feel hungry even after intense exercise,” Long says.
But why and how? Long, himself an avid runner and scientist, wondered if molecules that circulate in the bloodstream after exercise might be involved. These molecules likely travel to the brain and other organs, where they begin processes that cause hunger and dimming.
To find out, he and more than 20 colleagues took a deep look inside mice before and after they sprinted to exhaustion on a small treadmill.for studyThe scientists used a process called mass spectrometry to enumerate all the molecular-level changes involved in metabolism in the animals’ bloodstreams after exercise.
They found a lot. However, after the animals ran, one in particular appeared in large numbers. It was an obscure molecule that scientists had never named or classified before. Researchers have now determined the chemical composition of this molecule and found that it is a mixture of lactate, a substance produced in abundance by cells during intense exercise, and phenylalanine, an amino acid. The scientists named this “lac-phe,” and their data showed that the more lactate a mouse excretes during exercise (i.e., the harder it runs), the more lac-phe it has in its blood. I noticed that the amount was increasing.
Molecules that reduce appetite after exercise
Next, to see if lac-phe affected hunger, they injected lac-phe into inactive mice that normally enjoy eating. The animals quickly “cut their food intake in half in 12 hours,” Long said. Similarly, when we bred mice that couldn’t produce lac-phe and made them run intense races on a treadmill, the animals filled up afterwards compared to mouse runners who had higher levels of lac-phe. . Without this molecule, intense exercise stimulated appetite.
Finally, they checked for increases in lac-phe in people’s bloodstream after either gentle cycling, weightlifting, or sprinting for high-intensity intervals. “We found that sprinting produced the highest levels of lac-fe,” Long said, “followed by weight training and then aerobic exercise.”
In other words, intense exercise produced more appetite-suppressing molecules than light exercise.
The study caused a scientific stir, with some commentators speculating that: other paper Lacfee may eventually be refined into a medicinal product that can dampen people’s appetites without the need for strenuous exercise first.
Exercise doesn’t help you “earn” food
However, most exercise scientists believe that the effects of exercise on hunger extend far beyond the effects of single molecules. Studies have shown that exercise also has a profound effect on various hormones that help regulate how much you eat. In general, moderate or easy activity increases levels of hormones that make you want to eat more, especially a hormone called acetylated ghrelin (or simply ghrelin).
Tom Hazell, a professor of kinesiology at Wilfried Laurier University in Waterloo, Ontario, who has extensively researched exercise and eating behavior, said, “Exercise-induced suppression of ghrelin was demonstrated in our study using intense exercise. It’s consistent throughout.”
in new research A paper from his lab published last May found that nine middle-aged participants had significantly lower ghrelin levels almost immediately after intense training that involved repeating 1-minute or even 15-second intervals. It is said that he did.The results mirror his group’s previous results work, They also found that ghrelin levels plummeted immediately after a hard workout, and that ghrelin levels remained low for as long as two hours.
Interestingly, ghrelin levels in people in some of his group’s studies tracked inversely to blood lactate levels, similar to the lac-phe study. When exercise is intense and lactic acid levels rise, ghrelin tends to fall, which can suppress hunger.
A surprising variety of other body processes and parts, including the brain, are involved in movement and appetite as well.In modern animals the studyFor example, strenuous exercise temporarily alters the firing of hunger-specific neurons, increases the activity of neurons that appear to reduce appetite, and increases the activity of other neurons that suppress hunger. 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 sexes and between women. different stages of the menstrual cyclebetween the old and the young, between the heavy and the thin, or between the rats and us.
Perhaps most fundamentally, “thinking about exercise as a way to ‘earn’ food is a bad idea,” says Glenn Gaither, a professor of exercise physiology at Arizona State University in Phoenix who studies physical activity and weight management. says.
First, exercise burns very few calories. “In one of our studies, we had subjects eat two donuts,” he says, for a total of 520 calories. “It took him less than five minutes to eat the donut, but it took him nearly an hour or more to burn the donut.”
More importantly, like a Thanksgiving buffet, exercise has immense rewards, and weaponizing one to keep the other from cannibalizing can dull the enjoyment for both.
Still, if you’re looking to partake in a Turkey Day workout and cut back on your intake a bit, “high-intensity workouts like high-intensity interval training are best,” says Hazell.
Have fitness questions? Email YourMove@washpost.com I may answer your question in a future column.