I don't know if Jones is 100% accurate. I believe something like that is served to inmates who act up with regard to the food in the mess hall. If you throw your food, complain about it, refuse to eat it then you get all the foods composited together in a loaf.
What he's doing is the old time equivalent to bread and water. That, was used as punishment in days gone by.

Putting all that aside and considering his own words, let him eat that and nothing but that for an extended period.