So you want to "burn fat?"
Potential for Improving Endurance Performance through Substrate Conservation We know skeletal muscle needs ATP to contract and there are different pathways from which ATP can be synthesized. During endurance exercise, inevitably, some combination of glucose/glycogen and fatty acids will be used for substrate. Utilizing fatty acids for ATP synthesis could be beneficial for endurance athletes because humans have a virtually unlimited supply fatty acids, whereas stored carbohydrate is relatively limited - demonstrated below: 135,000 Cal from stored fat is roughly enough energy for a 65 kg person to run 2000 km (R. Margaria et al, 1963). A decreased reliance on carbohydrate and a subsequent increased reliance on fatty acids during exercise should help to "spare" muscle glycogen. Accepting the well documented theory that low muscle glycogen causes fatigue, one can see how glycogen sparing can potentially extend performance or allow for an acceleration late in a race. &q