A common myth is that working out on an empty stomach will help you burn fat, as there is no remaining fuel in your body to burn. As it turns out, this is not entirely true. The calories burned when you do not eat before a workout comes from the protein in your body, and this includes your muscle mass. Essentially, it means you are decreasing your muscle mass during your workout – when in fact, you should be maintaining or conditioning it!
Also, according to sports nutritionist Barbara Lewin, not fueling your body before a workout could mean that your body won’t be working out as hard. It’s similar to driving a car on an empty tank – it just won’t last as long as a car with a full tank.
The best time to stock up on energy is about 30 minutes to an hour before your workout. Your ideal pre-workout snacks should be loaded in carbohydrate, protein and fibre, for maximum energy and sustenance throughout your exercise.