If you could tap into >40,000 calories of your fat fuel during endurance exercise instead of relying on your maximum 2,000 calorie storage of carbohydrate fuel, would you do it? What if it meant no more liquid gels, sugar-containing sports drinks or bananas to give you that energy boost when you're on the verge of exhaustion? If LeBron James did it. Was it really a wise choice based on current science?