So, I've never actually READ this story, just seen it rec-ed. Of course, now that I WANT to read it, I can't find it anywhere. I'm just going to write what I remember from the summary.
Jensen's slightly overweight. His ex writes a story in a magazine about dating someone who's obese. This inspires Jensen into some sort of action.
Hopefully, that vague description will strike someone and I will FINALLY be able to read this story!