Go further back- Kings were heavy in size. Art showed fat curvy woman. Being large meant wealth. It was admirable and attractive

. A big women meant she was stronger and could work more. She was sought out.

The idea of of changing it to gluttony and weak was probably because the peasants were complaining, that they were hungry, and frail while the kings feasted. So let's change the concept around.

Just about anything that comes from an organized religion is basically meant to keep you suppressed.