It's rude to insult a person's physical appearance.
John is travelling inside a bus and an overweight woman boards the bus and sits next to him.
John wants to sit comfortably.
John switches to the back seat where there is plenty of space.
John asks the overweight woman to choose another seat because her huge body invades his space.
The overweight woman thanks John for being helpful and understanding.
The overweight woman feels embarrassed and leaves the seat.