Light people must eat as much as possible to become heavy so when they die they may achieve eternal peace, those who dont are reincarnated as lesser lifeforms, and they must continue to work until they achieve eternal peace by becoming heavy
The Book of Weight states that over 250 pounds is what the Supreme Peace judges as acceptable, and those who are naturally heavy are eligible to become Preachers of the Weight
The Book of Weight also states each crime deducts your overall pound rating by a number depending on the severity, for example, lying deducts you by 0.25 pounds, murder deducts you by 50 pounds.