Fit2fat2fit. Personal trainers have to gain 50+ pounds, then lose it with their clients. Both male and female trainers do it. I saw the last week's episode with a trainer named Katie, it was pretty cute seeing her gain that belly fat. Next week is a girl named Karrie who gains a big jiggly belly too.
Although it's an hour show, the first 20 minutes focuses on them gaining the weight. (Personally I love working out so the whole show is a treat)
I don't think that this site has a large fanbase around weight gain inflations, it's usually pretty rare. It's generally inflations with air or water, and not food to gain weight. You might want to try talking about that on a site like fantasy feeder (but it's certainly not unwelcome here, you just not get much of a response to that sort of sub-genre).
(Not on here too often, replies might be slow.)