Q: What's the best snack to eat and how long before my workout should I eat it?
A: In general, you don’t need to eat before exercise unless you tend to run low on energy during your workouts or it's been more than a couple hours since your last full meal.
The best time to eat is about 30 minutes before you begin to exercise, and the best snack is one that combines carbohydrates and protein (with an emphasis on the carbs). And you don't need a lot of food. Protein isn't a fuel for exercise, so you don't want to overdo it. For carbs, aim for the equivalent of a half bagel or a large banana; for protein, consider a couple tablespoons of peanut butter or a small cup of yogurt.
To get both if fresh food isn't an option, look for energy bars with 25 to 40 grams of carbohydrates and about 10 grams of protein. Steer clear of caffeine and warm fluids, which tend to speed food through your intestine, as well as dairy and high-fat or high-fiber foods, all of which can upset your stomach, slow down the absorption of carbs, and leave you feeling sluggish.
You should also stay well hydrated and avoid super-high-calorie snacks because you might end up consuming more calories than you burn off.
Rich Weil, MEd, CDE, WebMD Fitness Expert