Both body fat and glycogen are used for energy in the absence of food, but they aren’t used equally or at the same time. The body prefers to use glycogen for energy rather than body fat. This is logical because it is easier to burn glycogen—in terms of our analogy, it’s much easier to get food from the refrigerator in the kitchen than to trek all the way down to the freezer in the basement. And as long as there is food in the fridge, we won’t retrieve any from the freezer. In other words, if you need 200 calories of energy to go for a walk, the body will get that energy from glycogen as long
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