I don't know if it was just a coincidence that the need for a new saddle was accompanied by weight loss or not, but I'm thinking you are right. I was perfectly happy with the saddle that came with my bike (I don't even know what it was) until I lost some weight and even the shape of my butt changed. I suddenly needed a wider saddle, 'cos the old one just wanted to slither into places that it didn't used to--and that was rather painful. But it also could have been that the saddle had broken down... I don't know.