Scott, who is 60, could not understand why he kept slowly gaining weight. He was eating the same amount of food that he had each day since he was 20, and he got regular exercise. What could explain his weight gain

Slower metabolism.

Explanation: Our body's metabolism, its chemical processes that support life, starts to slow as we age. This means less efficient use of the energy contained in food which, if unused, gets stored as fat.  

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