A few months into my current relationship my now-husband started to do this. He'd note when I went back for seconds, would want to have discussions about "Which body part we'd change about each other if we could," which was a thinly veiled excuse to complain about my belly. This culminated with him wanting to have a discussion about my eating habits (which was really about my weight, because I fill up quickly and eat small portions, but I'm a bit of a grazer) and fears I'd end up like his father, who is morbidly obese.

Mind you, we'd been together about 3 months at this point, I'd fluctuated around ~5 lbs back and forth over that period, which is pretty normal for me.

I told him to go fuck himself. I mean, that's what I said. The relationship was new and he could accept me and my body for what it was right now and I'd do my best to maintain it but I'm not some fucking improvement project where I'm going to be made to feel like shit in my own relationship. I told him he had to accept me as I am or I'd leave and I meant it.

He apologized. It honestly took me quite a while to internally get over it. Years later he admitted that he actually preferred me body type and size but he was ashamed (yeah, I'm a big girl, not huge, but not skinny). Now, 11 years later he's obsessed with my big ass and owns his attraction to the cushin'.

Now this is a little different than your case b/c your bf knew you when you were really, really skinny but regardless you guys got together NOW. If he's got a problem with how you look now, you should tell him to find the door. It's not blowing it out of proportion to call this BS. Honestly - and I don't mean to hurt your feelings here - but I get the sense from your story that your BF preferred your looks in HS. So either he can a) deal with how you are now (which is 100% hot I am sure) or b) fuck off.