Ditzy:
Most of the guys I dated were in the 300 350 range.None gained or lost during the relationship.
I dated one guy who was very athletic and I got him to gain 20 lbs or so but he didn't like gaining on himself.
When we met I was 115 and when we split I was 250 ish.
He had no problem with me gaining and if it was what I wanted he was fine with it.
How long did it take to double your weight?
Has anyone been in a relationship where you are both gaining?