In short the answer if no. It really makes no difference in the amount of fat you burn in a workout, but . . . it can cause you to be more sluggish, making your workouts less effective. Why do we want the fat loss formula to be more complicated than it is?! I believe the key is eating when and how much you need to maximize your energy, hunger satisfaction, and sanity. While the body is a complex organism – very, very complex – there is a benefit for weight loss when we keep it simple. For more, check out the research results.