Anyone remember those pants they had in the 80s with an elastic at the back half of the waist and no elastic at the front half? What was the point of those? I know that personally the front part of my waist expands and contracts as I eat and breathe (sometime I think I would be a lot more comfortable in my clothes if I hadn't done five years of intensive music stuff in high school, which drilled diaphragm breathing into me so much that I have to make a conscious effort to breathe from my chest), but I can't think of any factor that would cause the back of my waist to expand.