I think it was the third season

I think it was the third season
I think it began right off the bat in the first season.

Here's another thing that was interesting about the fat jokes to me it was a double standard. Carol was not overweight and I believe the fat jokes got worse and worse each season to a point it went full tilt that she went into her problems. Good she got help for it and is recovered. Talking about anyone being overweight how about Ben and the way he eats. That does not make a good statement nor set an example for the children when we are encouraging them to be healthy and eat healthy. Ben was an unhealthy eater on the show.