You know that feeling after you’ve spent a ridiculous amount of time working on something and your brain is totally fried? The one where you’re so mentally exhausted, the only thing you can think about isplowing through a plate of greasy nachos, or a ginormous burger, or a cookie the size of your head?
Of course you do. It’s no secret that demanding work drives plenty of us to reach for junk food. It’s delicious, it’s distracting, it’s comforting, and most of all, it’s rewarding. (Report done—you just earned yourself a brownie.) It can also be pretty fattening, since 99% of us find ourselves buried under a brain-draining to-do list on a near-daily basis.
The good news is that science may have found The Thing that can stop you from wanting to eat junk when you’re burnt out from work. The bad news is, you probably aren’t going to like what The Thing is.
It’s exercise, according to findings published in Medicine & Science in Sports & Exercise. Researchers treated two groups of participants to an all-you-can-eat pizza lunch, where they tracked how many calories the participants ate. Then, the participants came back for another pizzafest the following week.
But this time, there was a catch. Before eating, both groups had to complete a mentally draining test. Then, participants in the first group had to sit and rest for 15 minutes before they could finally start chowing down. And participants in the second group were forced to complete 15 minutes of high-intensity exercise before they were allowed to eat.
Here’s where it gets interesting. Participants who rested after taking the test ate around 100 more calories’ worth of pizza than they did the week before. But participants who exercise after taking the test ate around 25 calories less. (Not to mention the fact that they burned additional calories from working out.)
Hard mental work forces your brain to eat up a lot of energy—and when the brain senses that its running low on juice, it wants to make sure that energy gets replenished, explains lead study author William Neumeier, PhD. Hence, your urge to steal the family-size bag of Cool Ranch Doritos from the break room.
But when you work out, your muscles release lactic acid into your bloodstream. “That readily available lactate would be an easy source of energy in the brain,” Neumeier says. Since your brain’s energy needs are replenished, you no longer have that overpowering desire to put food in your mouth.
Other factors could be at play, too. Exercise can stimulate hormones that temporarily suppress appetite. There’s also the psychological aspect: “Having a distraction like exercise could be the buffer [between mentally draining work and snacking] that you need,” Neumeier says.
Which all sounds great! Except, 15 minutes of intense exercise isn’t something that most of us desk-bound folks can pull off in the middle of a crazy day. So could you get away with something less, uh, sweaty—like a quick stroll around your building?
Neumeier wants to find out. But in the meantime, there’s no reason you can’t give it a try. “Perhaps if you’re aware of the findings and the strategy, maybe it doesn’t have to be 15 minutes of high intensity exercise,” he says. “Maybe going for a short walk first could be enough of a distraction or buffer to keep you from snacking.”