Most people probably think you should avoid eating directly before a gym workout. Not only because morning workouts can feel more effective, or because all that vigorous movement on a full stomach could leave you feeling nauseous; but also because some people believe if they don't carb-up pre-gym, the exercise will burn excess body fat instead of the stuff you've just put in your system.
And that way of thinking definitely makes sense where both logic and science are concerned; there have, after all, been studies carried out which indicated participants burned an average of 20 percent more body fat by exercising in a fasted state.
But as LifeHacker quite rightly points out, there are actually a few really big catches to this. They spoke to sports dietetics specialist Kelly Pritchett, Ph.D., R.D., who explained that when you start to burn fat rapidly—as one would if they exercise on an empty stomach—your body starts to adapt, adjusting your metabolism so it's in line with the fat burning. Essentially, it'll start going into "survival mode," slowing your metabolism right down and causing you to burn fewer calories. Exactly the opposite of what you're trying to do if you're exercising to lose weight.
There's also another benefit to fueling your body with food before you hit the gym; it's likely to suppress your appetite afterwards, so you'll eat less and save calories that way. As one study published in the journal Appetite revealed, the participants who had eaten pre-workout reported less of an urge to eat large portions of food later on in the day.
And if the motivation of your gym-going is all about building lean muscle, then working out on an empty stomach could be holding you back there, too. Fasted exercise can apparently lead to the shedding of muscle as well as the burning of fat. This could happen if your body has burned through its store of glycogen fuel and it's desperately seeking out energy to burn elsewhere—it'll look to the muscles. It's worth noting that this usually only occurs if a person seriously intensifies the amount of exercise they're doing, though.
Then there's the obvious: The less energy you give yourself for the workout by starving yourself of food, the less energy you'll have to really push yourself, hindering your progress.
So while it's usually recommended that people work out in a way that works best for them, it could be worth keeping this information in mind next time you're trying to plan a gym session.
This article originally appeared on Cosmopolitan.com/uk. Minor edits have been made by the Cosmo.ph editors.