No matter whether you start out as an apple or pear, your overall body shape will likely change as you age. This metamorphosis is due to a lot of factors that fall into two main categories: the ones that you can't control, and the ones that you can. The rate of these changes is connected to lifestyle factors like exercise, smoking, and the diet you consume. Here are the factors:The skeletal system that dictates the broadness of the pelvis, the width of shoulder bones, the distance between the pelvis and rib cage, and the shape of the rib cage deforms as you age. When a woman is pregnant, the rib cage widens because of the relaxing hormones. This is one of the reasons why post pregnancy, women lose their defined waist.