If a person were fasting and hadn’t eaten for several days in a row, which source of energy would the body use as a last resort?

After several days without food, the body has largely used its stored glycogen and relies mainly on lipids (fat) for energy. Protein can be broken down for energy when other reserves are insufficient, but doing so also breaks down body tissues, so protein is considered a last-resort source. The correct choice is protein.

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