The door to the dining area of the AlcobaƧa monastery in Portugal was made narrow so that monks who got too fat were forced to go into fasting. 
Discussion
The monks need to put down the fork
Go in, just about fit through the door.
Eat.
Can't get out now.
Stuck in the kitchen, getting fatter and fatter.
Never getting out.
I went to a monastery in Crete once, dude there was large.