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!