You should eat before and after the gym. An hour(or two) before going to the gym you should eat something healthy that give strentgh to your body considering you will be sweating, burning calories, doing things that will tire your body and eating will give you the energy to be able to work yourself.f you eat right before going to the gym it might hurt your stomach. I would try eating something small an hour or two before going and then after drink lots of water and wait maybe a half an hour then eating a regular meal. fizzgig037 · 8 years ago. Thumbs up.