South Koreans are typically taller and weigh more than North Koreans, with the average North Korean adult being as much as 5 inches (about 12.7 cm) shorter and about 14 to 27 pounds (about 6 to 12.5 kg) lighter than their South Korean counterparts. This is thought to be because South Koreans are more likely to have good nutrition as children. They also generally are less poor than North Koreans, which means that they often have better access to healthcare.
More facts about North and South Korean heights and weights:
The average new recruit in the North Korean army is about 4 feet, 6 inches (about 129 cm) tall. In 2010, the military lowered its height requirement of 4.5 feet (about 140 cm) by about 1 inch (2.54 cm), apparently because of the difficulty in finding enough recruits who meet the height requirement.
The average height of graduating high school seniors in North Korea is about 4.3 feet (about 134 cm), while the average height of a graduating senior boy in South Korea is about 5.6 feet (about 172 cm) and the average height of a graduating senior South Korean girl is about 5.25 feet (about 160 cm). The reason the height difference is more dramatic among teens than adults is that adults who were undernourished as children tend to hit their growth spurts later than those who had enough nutrition.
Being short of stature actually used to be considered a good thing in South Korea, because shortness was associated with determination. After Western culture became more popular in South Korea, being tall came to be associated with being successful.