-At the beginning of exercise, your body uses carbs at a very high rate since fat metabolism can not keep up up with producing ATP (energy) fast enough, so early in a workout. Carbs are quick energy makers but we know that utilizing fat for fuel can be a sustainable energy source so long as the intensity and duration are reasonable. (This is why a warm-up is very important before you begin your actual workout to help lower your HR and taking short walk breaks fr equently in the first 2-3 miles of a long run or race. To help your body metabolize the right fuels for your workout, wait around 10-15 minutes into your workout/race to start fueling (ex. on the bike and on the run but do not wait any longer than 20 minutes to ensure that your body receives the fuel it needs to help last the duration of your race/workout). But did you know that carbs are a rate limiting fuel? In order to continue to burn fat for fuel, you need carbohydrates during your workou
3x Author, Board Certified Sports Dietitian, Master of Science in Exercise Physiology, 2017 IM CHOO Amateur Female Champion, 19xIronman finisher including 6xIM World Championship finisher, Triathlon Coach, 30-year Vegetarian.Trimarnicoach.com