Seriously- why do people insist on humiliating themselves in this way?
Seeing as they're obviosuly having fun, I wouldn't go as far as to say "humiliate" - a lot of stuff folk do everyday in the name of fun could be classed as humiliating, it's very much in the eye of the beholder - but I do wonder at the expense and effort for such a shite result. And mainly because of the weight issues.
If for some reason you really wanted to look like Starbuck, Batman or a Clone Commando or whatever, surely you'd achieve a better effect putting the time into diet and exercise (and frequently orthodontistry, though obviously not for the Stormtroopers). As an on-off borderline-fatty myself, I kniow that it's not that complicated improving your physique (eat less shite, take more exercise - duh) - the problem is finding the motivating factor that keeps you going over the months - and surely if you're going to spend 100's of bucks on costuming yourself and prancing aound conferences, you have the motivation right there. You want to look a certain way - so do it.