Well fed by what standards? IMHO, rice hardly counts as food. It has to be the most useless foodstuff cultivated by man. Sure it's plentiful, but when bleached, etc. it's lacking in nutrients. All it does is take up space in your stomach. Well, enough of my anti-rice rant.
While well fed in comparison to their civilian brethren, I'm confident that NK soldiers are not receive the proper amounts of nutrients.