NEW YORK (CBS) Lydie Langevrn is training to be a personal trainer, so she's extra careful about what food she puts into her body before her feet hit the treadmill.
"It matters. It gives you more energy, gives you fuel to work out," Langevrn said.
Her coach and celebrity trainer Harry Hanson says eating the wrong foods right before you get your sweat on can drag you down.
Of course, fried or fatty foods are a big no-no, but high fiber foods such as vegetables can also cause problems.
"You don't want to eat anything that's going to sit in your stomach trying to breakdown while you're training, especially if it's an intense training session," said Harry Hanson, a personal trainer.
Spicy foods can cause heartburn or cramping, and carbonated drinks can leave you feeling gassy or full. Experts say nuts are another food you may want to avoid right before a workout. That's because nuts have a high fat content and it takes longer to digest foods high in fat.
Hanson recommends his clients eat a banana 20 minutes before a workout.
"Because it's a light carbohydrate, a complex carbohydrate which will sustain insulin into your, or sugar into your system over a long period of time," Hanson explained.
Dimitri Ouattara says he avoids anything that leaves his body feeling heavy before he trains.
"I like to feel light when I work out because I can do more. I feel more free. I'm more mobile," Ouattara said.
And what you eat after the workout is just as important.
Hanson says having a protein bar or lean meats and veggies will help your body recover and repair itself.