Question

how do nutritional needs change from young adulthood through old age?
fewer calories are needed.
fewer vitamins are needed.
more water is needed.
more protein is needed.

Explanation:

As people age from young adulthood to old - age, their metabolic rate generally decreases. This results in a lower energy requirement, so fewer calories are needed. Vitamins requirements may not necessarily decrease, water needs remain relatively stable, and protein needs do not increase.

Answer:

Fewer calories are needed.