It makes the fat person who has the cash feel better? So they come to your gym instead of a YMCA or Bally's? Shit, sounds like a good plan to me.
They could have something like a Jared at Subway, but who hasn't heard of someone losing weight at the gym? People losing weight eating fast food is completely different.
I'm sure they could come up with something inspirational, but it is appealing to the fat masses to go to a gym where they fit in, and people in good shape aren't around.
Think of it this way. How often do you guys go to the gym? 3-6x a week? You pay the same amount as everyone else at the gym yet you probably do 10x the wear and tear to the equipment than anyone else (through natural use).
If they can get more people (fatties) to sign up and pay the same amount as you, and then not come to the gym - they make money and don't have any wear and tear on their equipment. Win-Win.