Well, maybe it's not so bad. The main character discovers that his weight decreases a little every day even if his appearance doesn't. His beginning weight is 240 pounds and he looks no different when he dips under 200, 150, 100 pounds, etc.
He also weighs the same naked or clothed. If the scale shows 200 pounds when he's fully dressed, it will still register 200 pounds when he's naked.
It seems Thinner-ish, but it's interesting.
Unfortunately, it's dumb aside from that.