The rationale behind this widely accepted myth is that forgoing food before exercise will force your body to burn more fat during your workout. This is a big, fat lie: Starving yourself before exercising can actually be detrimental to your body. You need sugar to exert energy — and you need energy to perform at high intensity. I suggest eating a healthy snack 45 minutes to an hour before training. Aim for something with carbohydrates and protein like a whey shake, low-fat yogurt with berries, or a banana or apple with natural almond butter.