It's bad to be a glutton.
Karen is at a buffet selecting food to eat.
Karen wants a satisfying meal that tastes good.
Karen eats sensible portions of food.
Karen loads several plates with more food than it takes to make a person full because it's the same price.
Karen feels full, but not ill, and everyone around has enough to eat.
Karen makes herself sick, and others around KAren have less food and see that KAren is greedy and piggish.