In terms of metabolism, what change occurs as one ages?

As individuals age, changes in metabolism are observed, and it is well-documented that metabolism generally slows down. This slowing is attributed to several factors, including a loss of muscle mass, hormonal changes, and alterations in cellular function. Muscle tissue is metabolically more active than fat tissue, so as muscle mass declines with age, the overall metabolic rate decreases. Additionally, hormonal shifts, particularly decreases in growth hormone and sex hormones like estrogen and testosterone, also contribute to the reduced metabolic rate. Therefore, it is understood that aging leads to a gradual decline in metabolic processes, making the correct choice clearly reflect the biological changes associated with aging.