I accidently made my friend feel bad

I was at school, and me and my other friends joke around-in a way were rude to each other. So the other day (Friday) we were on the bus, and me and my guy friend are both gym people (love working out). And he's called me fat before, but it was a joke, and I never took it seriously. But when we were on the bus I told him " I had almost visible abs but I got depressed and gained weight" cause I got super depressed a few years ago and it kinda comes and goes every now and then. 

    I could tell He kinda felt bad when I said that, and I only thought about t after we left the bus, but we changed the conversation almost immediately after that cause who wants to talk about depression with the unserious friends, like that is something for my other friend group.