General

It really won't help to get an opinion here, because everyone is different. One of my fondest memories was a relationship with a woman who was short, thin, had short hair, and was older than me. The break up had nothing to do with anything physical.

But, at the same time, attraction is important. If he is hanging around waiting for you to change, you are both wasting your time. It is a shame to waste your thinness on someone who likes big woman, and it is a shame for him to waste his FAness on a thin woman.

If time is not important, I would go with the flow and see how it goes. If you are looking for a longer term committment, and don't want to waste a lot of time on something that might not work out, I'd have a serious conversation with him.

Best Advice.

For all you know, he's been wanting to bring it up for ages but just never knew how to, this could be great for both of you and your relationship.

Not to mention, if it was such a big issue for him he probably wouldn't have stuck by you for so long.

Don't take it personally either, this sort of thing is more about him than you.