pig out

Definition: (verb phrase) overeat
Example: Elvis loved to pig out on fried banana and peanut butter sandwiches.
Quote:
"Oh my God, it's insane-she has the most beautiful figure. And I heard she pigged out on Chinese food right before we shot."
- Drew Barrymore, talking about Demi Moore in the new Charlie's Angels
movie
Though we say pigging out for "eating too much" we don't generally use pig to mean a fat person. (Pigs are usually unpleasant or selfish people.) However, porker (like "pork") can be used to describe someone larger than average, as can cow (to describe women only) or whale. Hopefully, your manners are too good to use any of these.