I still wonder how a prisoner Will choose to engage himself into gambling with his food when they berely eat, isn't that foolishness!! When their major concern is supposed to be on how they're going to feed well rather than gambling with the little that is given to them.
Of course the food that they will bet on are not the food they only have or their food ration for that day. It's usually food that their relatives or friends that visit them bring.
Prison food is not good as we know and hey taste very bland from what I've read. It's a luxury for them to have eat something that is from outside the prison like chips, chocolates, and even the taste of homecooked meals so using it as a bet on gambling inside the prison is worth it for them as long as both parties agree.