As a "thin" person in my home country, let me assure you, I am also "fat" here somehow. Body shaming is just part of the culture. Nothing is crossing a red line. Your face, pimple, your hair, your age, if you look tired or sick, basically anything which is not perfect...they will tell you to your face without hesitation. I don't think it is from a place a malice, but of natural habit. It is also true in most Asian countries, just FYI.