Which of the following physiological variables increases with age?

As individuals age, it is common for body fat to increase as a physiological variable. This change is often influenced by several factors, including hormonal changes, a decrease in muscle mass, and a reduction in physical activity levels, which can result in a higher proportion of body fat relative to lean body mass.

Unlike muscle mass, which typically decreases with age due to factors like decreased physical activity and hormonal shifts, body fat tends to accumulate, particularly around the abdomen. This change in body composition can impact health risks and overall wellness, as increased body fat is often associated with various health issues such as cardiovascular disease and metabolic syndrome.

Bone density generally decreases with age, especially post-menopause in women, due to changes in hormones and calcium retention. Stamina, or aerobic capacity, typically declines with age as well, largely due to decreased cardiovascular efficiency and a decline in muscle mass. Thus, among the given choices, body fat is the physiological variable that is known to increase with age, making it the correct answer.