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Hint: It's better to earn that hearty breakfast. 

Elisabeth Sherman
Updated April 17, 2019

If you’re an exercise fanatic, a devotee of #fitspo, or a self-identified “gym rat” you’ve probably wondered if it’s better to eat breakfast before you work out or afterwards. Some people worry they’ll suffer cramps if they eat a big meal before hitting the gym, while others swear by feasting beforehand as a way to boost their energy. Confused yet? Not to worry, science has finally weighed in with an answer.

In order to unravel this mystery, researchers at the University of Bath had 60 overweight male volunteers walk for 60 minutes on an empty stomach, and then again two hours after eating a carb-rich breakfast. They then took blood and fat (or adipose) tissue samples. They found that stored fat fueled the volunteers' metabolism, rather than the carbs from the breakfast – which means that even if you did enjoy a hearty meal before your workout, your body probably won’t even use it to sustain you during exercise. 

GQ reports that the researchers were not messing around with the meal they gave to their volunteers: It consisted of thick white bread—covered in a layer of butter and jam—cornflakes, skim milk and orange juice. 

The study went even further to discourage people from eating before a workout. Turns out, adipose tissue is “busy responding to the meal and a bout of exercise at this time will not stimulate the same [beneficial] changes in adipose tissue,” Dylan Thompson, one of the authors of the study wrote. “This means that exercise in a fasted state might provoke more favorable changes in adipose tissue.”

So there you have it: If you do choose to eat before a session at the gym, your body will be more focused on processing the meal, basically distracting it from exercise. There’s a big “however" attached to the study, though: It doesn’t cover the effects of eating a big meal before lifting weights, which means that if you’re trying to bulk-up, this new information is probably not relevant to you. 

But for the rest of you out there just trying to get trim for the summer months, the verdict is: Wait for that big meal until after you’ve earned it at the gym.