Responses
its kinda ironic because back in ancient china (and the west as well) slim/skinny people were considered lower class poverty and were disliked. whereas "fat"/bigger people were considered part of higher class. it also meant u had a lot of money (enough to buy a lot of food, etc.) which is why a lot of people back in the days stuffed themselves.
and now everything is the other way around (in most ways) and people are trying so hard to follow beauty standards.

I think reading this arc with some awareness of Chinese beauty standards helps (thin : beautiful and alluring, fat: overweight and lazy), especially in ancient times. The concept of 'everyone is beautiful no matter what your body shape' is more prevalent in West, and is completely different in Asia. This is primarily a Chinese manhwa with it's intended audience being Chinese.
Chinese artists would never create an 'overweight' heroine with this. Villains and second female leads, yes, but not the main characters, sadly.