My body must defy science or something because I swear, when I work out really, really hard, I’m pretty much starving afterwards. But pay no attention to me, I guess, and listen to the findings of the latest study on appetite and exercise—namely, that intense exercise actually suppresses appetite.
Here’s why: Researchers at the University of Western Australia took 17 overweight but otherwise healthy men and had them hang out at the lab on four separate days. The first day, really, all the did was hang out: The men read or rested for 30 minutes. On the other three days, the men completed workouts that ranged from moderately demanding to slightly more demanding to very demanding. All of the workouts lasted for 30 minutes.
Before and after their time in the lab, researchers drew some blood to record the levels of certain hormones and other substances that have been shown to influence appetite. They also fed the men a so-called “liquid breakfast” (I’m thinking a smoothie) right after their workouts, and 70 minutes later, offered them a “sweetened but bland porridge,” according to the New York Times. “The researchers wanted to avoid rich aromas or other aspects of food that might influence the men’s desire to eat; they hoped to isolate the effects of pure appetite—which needs to be robust to make porridge enticing,” it explains.
Now for the kicker:
As it turned out, gruel was quite appealing to the men after resting or pedaling moderately; they loaded their bowls. But their appetites were noticeably blunted by each of the interval workouts, and in particular by the most strenuous 15-second intervals. After that session, the men picked at their porridge, consuming significantly less than after resting or training moderately.
They also displayed significantly lower levels of the hormone ghrelin, which is known to stimulate appetite, and elevated levels of both blood lactate and blood sugar, which have been shown to lessen the drive to eat, after the most vigorous interval session than after the other workouts.
After the high-intesity workout, the men also continued to eat less through the following day, which means the appetite-suppressing effect had at least some longer-term effect. Researchers caution, however, that the effect on appetite of high-intensity workouts over time hasn’t yet been studied or determined, so it’s too early to say if doing a lot of HIIT workouts would translate into a measurable weight loss—but it does stand to reason.
If you’re looking for some high-intensity workouts to get you started, check out our BeWOW series for some good ideas. Many of the workouts we’ve posted weekly for over the past year are fair game.