Those who exercise in a fasted state experience a lower level of performance. Without fueling your body, you might not be able to exercise as long or as intensely, or you may have less energy or even dizziness if your blood glucose level drops. You may also tend to overeat after you exercise or later on in the day.
Your body breaks down the food you eat into glucose in your blood, or as stored energy called glycogen in your liver and muscles. Having glucose provides you with energy production for your workout. It can also prevent you from experiencing low levels of glucose, called hypoglycemia, which can lead to dizziness and fainting. Drinking fluids or eating foods that contain water before you exercise is also beneficial to avoid dehydration, which also impairs performance.
Small meals or snacks should be eaten one to two hours before exercising, so this may be your best bet for your pre-workout meal. While these guidelines are helpful, everyone's digestion is different. You may find that you need to eat earlier or later. Experiment with the timing of your morning snack or breakfast to allow for enough time for digestion to avoid gastrointestinal discomfort but still feel energized.
Stick to foods that you know will not cause gastrointestinal problems, trying new foods might cause problems. If you find eating before exercise uncomfortable, try a liquid drink, like a shake. Your pre-exercise meal should contain mostly carbohydrates, with some protein. Select food options that are low in fat and fiber.
Eat a low calorie meal (snack) to get yourself started. Drink water too, to stay hydrated.
Better leaving the heavier meal for post workout.
Eat before as you need energy to excersise, eat something healthy that can fill you up