Funny tees with sayings like "I run for pizza" or "I run because I really like beer" goofily sum up the way many of us think about the relationship between food and exercise. Who among us hasn’t pictured the delicious snack waiting for us after a killer workout, for example? But what happens when our exercise routines cause us to consistently overeat? Many of us typically associate a regular fitness practice with healthier eating choices and maybe even a svelte physique, but the relationship between working out and overeating has both biological and psychological roots that may surprise you.

But I Need to Refuel My Muscles... Right?!

Beginning a new exercise regimen or adding new challenges to your current routine may require that you up your caloric intake in order to recover from workouts and keep energy stores full. And our bodies usually tell us as much, naturally bumping up our appetites after workouts. But can exercise make us eat more than we truly need?

For every 10 calories we burn, we’re expected to crave at least three—a biological compensation mechanism that ensures we remain properly fueled Cross talk between physical activity and appetite control: does physical activity stimulate appetite? Blundell J.E., Stubbs R.J., Hughes D.A., et al. Proceedings of the Nutrition Society. 2003 Aug;62(3):651-61. . But some people tend to overcompensate for the number of calories lost through physical activity and exercise-improved metabolic rate, consuming eleven or more calories for every ten burned, says endurance trainer Matt Fitzgerald, author of Diet Cults and Racing Weight. The reason? A combination of physical and psychological forces—some of which we're entirely unaware.

In many cases, “it’s reward psychology at play,” Fitzgerald says. “You see this more with beginners who aren’t intrinsically motivated to exercise; they simply don’t love it. Newer people, for whom an activity itself isn’t rewarding, may choose to reward themselves with a food treat—eating more than they normally would, or eating foods they’d otherwise avoid.”

It’s one thing to use that delicious post-workout snack as motivation to finish a run, but when working out is a straight-up brutal slog, we may find ourselves seeking comfort or reward through food.

When Exercise Makes You Overeat

Even if you've sidestepped the pitfall of food rewards, there's another common mistake: overestimating the number of calories burned during exercise while underestimating the calories taken in. This can happen whether we’re prone toward overeating or not. As one study showed, subjects trying to lose weight reported eating 47 percent less and working out about 51 percent more than they actually ate and exercised, meaning we might be regularly overcompensating for what we've burned Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. Lictman S.W., Pisarska K., Berman E.R. New England Journal of Medicine. 1992 Dec;327(21):1893-8. .

The Biology of a Post-Workout Binge

Research into how exercise might trigger urges to overeat pegs the blame on biological factors. For certain people, especially the obese, challenging bouts of exercise cause massive neural activity upticks in brain regions responsible for food reward and craving Low fat loss response after medium-term supervised exercise in obese is associated with exercise-induced increase in food reward. Finlayson G., Caudwell P., Gibbons C., et al. Journal of Obesity. 2011;pii:615624. . That said, the more lean you become and the more accustomed your body grows to regular workouts, the less powerful those urges may feel. Studies investigating the brain activity of fitter, leaner folks show their food-reward centers respond less aggressively to images of tasty edibles. That leads researchers to believe that while upping physical activity may initially provoke urges to indulge amongst newbies working out, over time those urges wane as healthier habits become the same ol' same ol' Aerobic exercise reduces neuronal responses in food reward brain regions. Evero N., Hackett L.C. Clark R.D., et al. Journal of Applied Physiology. 2012 May;112(9):1612-9. .

Registered dietician and Greatist Expert Erica Giovinazzo reminds us that letting ourselves get too hungry is a guaranteed setup for a binge. And that might go double for those newbs adjusting to the increased caloric burn of regular exercise, which triggers the need for a few extra post-workout calories.

“Whether you’re working out or not, you never want to be completely starving at any point in the day. When that happens, we tend to eat a lot more than we normally would—mainly because eating is as much mental as it is physical.” Being ravenous makes us eat faster, leading us to miss out on satiety cues which normally take 15 minutes or more to kick in.

Giovinazzo’s advice? Eat more mindfully (try putting down the fork a few times during your meal or chewing a little longer), portion out your meal like you would if you weren’t famished (chances are, the amount you normally eat should still satisfy you), and stand up mid-meal if you can (sometimes we don’t register how full we are until we get up from the table).

The Takeaway

Hunger is the body’s way of asking to be refueled, so don’t ignore a rumbling stomach, particularly if you've recently started working out or ramped up your exercise routine. Stronger hankerings than usual may be a sign your body and brain are adapting to a new set of physical challenges, but craving tons of treats may also be the mind’s way of asking for equal attention in the form of rewards and comfort food. Try to tune in to the difference between physical hunger and the emotional desire to eat, and hang in there as you learn to accommodate new habits. Opting for more fruits and veggies will promote feelings of fullness, and staying fueled and hydrated throughout each day could stave off binges.

When it comes to getting a handle on emotional eating, it's worth remembering that forcing ourselves to do workouts so torturous that we look to food treats as rewards will likely only fuel an unhealthy cycle of emotional overeating. So find the activity you love, hit your favorite classes, work out with a pal, or create a killer playlist to fuel your cardio sessions. Once we get fitter and exercise becomes its own reward, the physical and emotional need to overeat falls by the wayside.

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