Here's a real shot in the a--

Depending on whether you want to get your meds delivered via your fanny, there may be yet another reason to try to reduce your size:

The expanding size of people's bottoms is presenting doctors with a new medical challenge: how to get injectable drugs to where they are needed.

[...] For drugs to be effective, injections must be delivered into muscle which is supplied with microscopic blood vessels, to maximise absorption of the medicine. But the larger size of the average backside means the muscle is now covered with a layer of fat and the standard needles fitted to syringes are not long enough to penetrate it.
-- Independent Online Edition > Health Medical

So will health care costs rise because of the increasing sizes of needles needed to deliver the goods?

Whatever happened, by the way, to the whole Star Trek method of injecting via molecular mist through the sleeve of your uniform? What's with this nineteenth century sharp pointy objects in the butt, thing, anyway?