Why do people keep telling me to gain weight?

I'm 165 cm and 53 kg. That's actually pretty healthy and I don't think I look scarily thin. Sure I'm thin but I eat normally and that's how I've always been.

People keep telling me to gain weight though which is annoying as fuck. I feel like they wouldn't tell me I need to do that if it wasn't for the fact that I wear a 32A so I look thinner than average when it comes to my upper torso. Also, why is it okay to tell me to gain weight if it's offensive to tell people to LOSE weight? Aren't those questions virtually the same? Lol rant over.
Why do people keep telling me to gain weight?
Post Opinion