There was a picture floating around on the internet. It was an old photo from a meeting between the US and both Koreas. There were three Soldiers in the photograph. There was a typical American Infantryman, over 6' and looking like a badass. Then there was a South Korean soldier almost as tall that looked like he could probably kill a dozen people with his bare hands. Then, there was a young boy, looking about 8 years old and maybe 4' tall, in a military uniform. It was an adult in the North Korean military. Now, when countries get together like this, they send Soldiers who they feel will best represent them, so you have to consider the fact that this on-the-verge-of-death little kid was one of the best that the North Koreans had.
North Korean soldiers on the DMZ, which is the most important place, get about 800 calories a day. Before they joined the military, they got much less. North Koreans frequently have stunted growth and all sorts of development issues because their shit-bag leader spends all of their money developing weapons that even the most hard-up revolutionaries wouldn't be caught dead with.