Why do energy needs often decrease with advancing age?

Our bodies aren't working as hard to constantly replace cells as we age, thus we require less energy.

Explanation:

In a novel study comparing healthy cells from people in their 20s with cells from people in their 80s, researchers at the Johns Hopkins Kimmel Cancer Center say they have documented that cell division rates appear to consistently and markedly slow down in humans at older ages

well when looking at this if you think about it   negativley and positivley   react with each other and when the first layer gets full they add layers it starts with 2 on the first layer and it constantly goes on until the official number is there

answer normal force;