What to eat and how much to eat before a workout are highly dependent on how what you have already eaten during the day, what you plan to eat after your workout, how hard you’re training, and personal tolerance. For instance, some people do well exercising on a full tank, while others become nauseous if they exercise too soon after eating.
Energy to burn
Regardless of personal tolerance, it is important that you have something in the tank. If it’s been longer than two hours since your last meal or snack, it’s likely that your workout will drag because it does not have a readily accessible energy source to draw from. It’s easiest for your body to digest carbohydrates soon after consumption. If your body is forced to burn stored fat, the result is a slower, more fatiguing process that can leave you feeling zapped halfway through a set.