Is obesity (over eating) a sin?

A friend and I got in a silly debate about Christians and what we identify as the "Tier of Sin". How most Christian communities value "major" sins (Homosexuality, Adultery, Murder, etc.) over the "lighter" sins (Lying, Fornication, Gossip, etc.). Personally, I believe God is disgraced by all sins equally, but I can't help to notice that congregations seem to rebuke some sins more aggressively than others. Anyway, I threw over eating onto the tier. And Jay says, "I can't imagine someone squeezing through the gates of heaven only to be told they have to leave because they were fat." Still, gluttony is a sin? Aren't the people that over eat their way to obesity committing the sin of gluttony? Is it a sin? If so, why do we hardly talk about it in church?