Being skinny does not mean that a person is not a glutton. Their body may burn it off. But they are taking more than their fair share of food perhaps at meal time or when a guest a someone's house.
There is one sister at the hall who was known at every gathering for eating or taking home all the extra food. She was not thin per se but not very large either, she just had decent metabolism.
But nope since I still haven't made the final cut from the borg there is no one I know of who has been df'd or had a jc for it. Ironic isn't it.
The only time I go to buffets is when my rents want to go somewhere fairly cheaply.