By the way, if you want to be 'correct' about archaic/Middle English, it's "Art thou a glutton?" if you're asking a single person, or "Are ye a glutton?" if you're addressing a group of people, like in this post. "Is" is incorrect in Middle English for the same reason it's incorrect in modern English, and "thee" is the singular objective case (and you want the nominative).
Personally, I feel often like I eat an enormous amount of food, but I'm still pretty skinny. And as for gluttony, I feel that being addicted to food and not trying to recover (or not trying much) is worse than being addicted to drugs while attempting recovery. Many fat people, from my experience, stay fat and blame their condition on everything from genetics to not having enough free time, and there's plenty of support out there encouraging fat people to be 'proud' of their bodies and whatnot, and not worry about what they're eating. Addicts to alcohol and cigarettes act similarly, making every excuse one can think of, though there's less social support for them. Addicts to 'hard' drugs, though, I think are typically much more concerned and tend to make more of an effort to quit their vices, because of the more severe consequences (and perhaps the ones who don't just die).