I Am Naturally Thin and People Think I Am Anorexic

I get criticized for it. Even my mom's friend thought I was too thin. It's like just because I'm thin they think I need to eat. My mom's friends thought I was looking too thin. She said, "You're looking a bit too thin sweetheart. Let me fix you something to eat." I told her no thanks. But she insisted that she does. That irritated me so much. I said NO THANK YOU. I had just ate. I'm naturally slim okay? I'm 5'5 and 124lbs. I'm slender built. Now if someome was anorexic I understand but I'm it anorexic. Is being naturally thin a bad things nowadays?