Why do adolescents require higher energy expenditure compared to young adults?

Adolescents have higher energy expenditure compared to young adults primarily to support normal body function and higher activity levels. During adolescence, individuals are experiencing significant physical growth and development, which includes increases in muscle mass, bone density, and overall body size. This growth necessitates a greater caloric intake to fuel the processes of development and to supply the energy needed for daily activities, including both structured exercise and general daily movements.

In addition to growth, adolescents often have higher levels of physical activity than young adults, which contributes further to their energy needs. Engaging in sports, recreational activities, and other forms of exercise can significantly elevate energy expenditure. Thus, the combination of physiological changes and higher activity levels means that adolescents require more energy to support their overall health and well-being.

This is why the option related to normal bodily function and higher activity levels is the most accurate representation of the needs of adolescents during this critical stage of growth and development.