Aerobic exercise is the most effective way to burn fat calories.
When the exercise begins, it is primarily fueled by carbohydrate. As time goes on, carbohydrate as a fuel source decreases and fat use increases. Another relevant item is that fat is preferentially utilized in moderate intensity exercise. High intensity exercise requires energy to be supplied at a rate faster than fat metabolism will allow and, therefore, high intensity aerobic exercise will preferentially try to use carbohydrates.