watch on kim's appearance, specifically his weight. side by side video comparisons indicate kim appears much thinner now than he was last year. last fall, south korean intelligence officials told lawmakers they believed kim's weight had ballooned to over 300 pounds in 2020. but photos of kim's $12,000 wristwatch show in the most recent picture on the right, it is now fastened on a tighter notch than in previous sitings. why is kim's weight such a priority for intelligence agencies? >> because we know so little about the north korean leadership and their intentions, we don't know who would succeed him if he were to die suddenly. >> reporter: if kim jong-un were to die suddenly, most analysts say his younger sister, kim yo-jong, believed to be about 33 years old, would take power. her stature and responsibilities have increased in recent years. could she survive? as one analyst points out, each time there's been a succession with the kim dynasty, north korea watchers have predicted it would fail. and more than 70 years in, the