I have always said in the past many time that how well you take care of your self in your 20's will depict how eay it is to take care of your self in your 30's and how well you take care of yourself in your 30's will depict how easily your body responds in your 40's ect, ect. It also important to remember though that this can go both ways. People who have alot of body fat useually have a much harder time keeping it off over the long haul as ( And I guess the yo-yo syndrom can apply here) the body remebers what it is use to. I have always heard that your body has a set number of fat cells that are developed during your adolesscents. Once grown, your fat cells simply increase in size not number. Unless one has had some form of lipo suction this number does not go down they just simply deflate. Thus the reason for many to yo--yo after returning back to their old way of life.
Tobey