A Answers (2)
Eating prior to exercise will depend on the type of exercise you are completing. Are you focusing on strength training, cardiovascular training, or both? Prior to exercise you should be sure to eat some form of a carbohydrate. This might consist of something starchy or something such as a fruit. Much will depend on how your body responds so experiment with a few varieties of food and have something with you in case what you choose did not seem to stick.
American Diabetes Association answered
What foods you use depends on three things - the type of exercise you are doing, the duration and intensity, and your blood glucose level before exercising. If your blood glucose is below 150 mg/dl before you exercise, it is probably a good idea to eat about 15 grams of carbohydrate. This could be a serving of starch, fruit, or milk. You might also consider using foods that you really like, but usually don't eat because they have a negative impact on your blood glucose levels. One athlete we know enjoys eating a Snickers bar before his workouts. As he says, "I know there are better sources of energy, such as sports drinks, but I really like Snickers. So the way I see it, if I need to scratch my chocolate itch, I might as well do it when I know that the exercise will burn up most of the glucose!"