Help making my GF more comfortable with herself.

My girlfriend is a skinny girl that has gained a tiny bit of weight over the holidays. Nothing huge, just enough that she now has a mini-roll when she leans forward. She comes from a household where any amount of fat is demonized, so I'm hoping someone can give me a few tips on how to make her more comfortable with the idea of having a little extra poundage. It'd be cool if I could convince her to keep the weight or even gain a little more, but my first priority is ensuring that she is completely happy with her body as it stands now. I'm not looking for devious ways to fatten her up or brainwash her. I just want some day to day techniques that will let her love her starter roll as much as I do.

Once I get her comfy with that, it'll be a lot easier to talk to her about being an FA. Discussing fat with a perpetually skinny girl is like talking sex with a virgin. They turn it into weird theoretical physics after a while. I'd like to express my eternal gratitude in advance to anyone who can sound off on my dilemma.