Two constant threads that have run through the history of North Korea: Rule by the Kim dynasty, and speculation about the health of its secretive leaders.

The latest incident took place this week when US officials said Monday they were unsure of Kim Jong-un’s health after they were told he was in critical condition after undergoing cardiovascular surgery.

South Korea’s presidential office subsequently said Kim was conducting normal activities in a rural part of the country.

Trump Says ‘We Don’t Know’ How Kim Jong-un Is Doing 

Heavy smoking, bulging waistlines and mysterious ailments have passed from state founder Kim Il-sung to his son Kim Jong-il and then to his grandson, fueling countless speculative reports about their treatments and prognoses.

Their actual health condition has been known only by a small circle of their most-trusted aides, with the outside world in the dark.

Here is a rundown of some of their health scares:

Kim Il-sung, 1912-1994

One of the biggest health concerns for the man North Korea has enshrined as its eternal president was the almost tennis ball-sized growth on the back of his neck, which was caught in photographs on international trips over the years. His propaganda machine made sure it was never shown to his public.

While Kim Il-sung passed away in 1994 at the age of 82, rumors that emerged about his death in the 1980s weren’t about his health.

Rather, messages blasted from North Korea through a loudspeaker at the heavily militarized border with South Korea said he was killed in an assassination, prompting reports of his death to travel the world.

Two days later, state-run media showed him very much alive at Pyongyang airport to meet a delegation from Mongolia.

Kim Jong-il, 1942-2011

The man dubbed by state propaganda as the “Dear Leader” died in 2011 of a heart attack at the age of 70 after a life of hard drinking, heavy eating and decades of chain smoking.

During his 17 years in power, he was once the world’s largest purchaser of Hennessy Paradis cognac, and reports said he sent aides to Beijing to pick up McDonald’s Big Macs.

South Koreans who met him in 2000 at the first summit of the leaders on the divided peninsula said he had a penchant for rich and greasy food.

Kim Jong-il’s tendency to disappear for weeks combined with his poor habits led to years of speculation about an imminent demise. In 2007, he returned from a prolonged absence looking thinner around his waist and with less hair in his trademark bouffant, giving rise to speculation that he suffered a heart attack. Another prolonged absence in 2008 triggered rumors of a stroke.

Kim Jong-un, 1984-?

The 36-year-old leader was conspicuously absent from a major celebration on April 15 to celebrate the birthday of his grandfather, triggering the latest round of speculation.

Kim Jong-un has ballooned in size since taking power in 2011, and has been seen puffing away on cigarettes in public appearances, as well as on the sidelines of summits with US President Donald Trump.

South Korea’s spy agency believes he also suffers from high blood pressure and diabetes, the Yonhap News Agency reported.

In 2014, Kim Jong-un went missing for six weeks and came back walking with a cane and a limp during a visit to a new residential block. In a rare bit of candor, North Korea’s state media said during his absence said he was experiencing “discomfort” in his body.

Outside of North Korea, media reports offered conjecture that he was suffering from gout due to a diet of rich food as he put on weight to more closely resemble his father and grandfather. (Bloomberg)