So I have these two friends that are girls that I met at the beginning of the year. Kept my distance from them at first but throughout the year I've become closer and closer friends with them. Anyway, earlier tonight we were discussing how I wanted to get down to less than 10% body fat because you're more defined. They saw this as unhealthy and we went back and forth on this issue for a bit. Summary of conversation:

*Me: I realize you need body fat, but 7% is still a healthy amount.

*Them: No it's not.

*Girl A: I'm at like 20% and I'm an athlete. It's normal.

*Girl B: Me too.

*Me to girl A: That's rough (nonchalantly and in a jokingly manner)

Girl A: That's so rude! *Storms off followed by girl b

Fast forward 10 minutes I pass them in the hallway while getting a drink.

*Girl A: I want an apology that was so mean to say to a girl

*Me: No, why would I apologize? I've done nothing wrong

*Girl b: You degraded her and attacked her self-esteem. You don't say that to women.

*Me: I didn't mean it personally. You both have known me. When am I not jokingly mean?

*Them: It doesnt matter.

*Me: You're overanalyzing what I said. You're both beautiful women, you shouldn't have self-esteem issues. Get over it

*Girl A: I've lost all respect for you. Don't talk to me. Have a nice summer

*Them: Apologize

*Me: Fine, I'm sorry "Girl A". Are we done?

*Girl A: That's all I wanted. We could've saved 10 minutes

Post drama I see that even sparing the time to argue with them in the first place was a mistake and that they had absolutely no logic. I came into their frame, unfortunately. I find girl A attractive and she somewhat knows this but I've never confirmed it to her although I've never thought too much of her because her and girl B are inseparable and she has a boyfriend. Stil, I believe that's what led me to cave. What I'm confused by though is why girl A reacted with such hostility and emotion to one petty comment? Also, any feedback on how I could've handled the situation better would be greatly appreciated.