North Korean leader Kim Jong-un is currently suffering from insomnia, as well as diseases caused by obesity, South Korea's intelligence agency said Friday, adding he has gained 40 kilograms over the past four years.

The National Intelligence Service said in its report to a meeting of the parliament's intelligence committee that Kim is presumed to weigh 130 kilograms, a jump from 90 kilograms when he took office in 2012.

Rep. Lee Cheol-woo of the ruling Saenuri Party, who chairs the committee, said Kim is currently under great stress due to his safety, which has led to excessive binge eating and drinking.

Kim also fears that overseas media reports on his childhood may spread throughout Pyongyang, which may hurt his legitimacy as the leader of North Korea. 

During his childhood, Kim would stop eating for long periods of time when his mother scolded him, which reflects his stubborn character, Lee quoted the NIS as saying.

Kim Kyong-hui, who was once a powerful aunt of Kim Jong-un, meanwhile, is currently living in the outskirts of Pyongyang, after suffering from alcoholism since her husband Jang Song-thaek was killed, the NIS added.

The former vice chairman at the all-powerful National Defense Commission was unexpectedly executed in 2013 on treason charges.

The agency said while Kim Kyong-hui is currently fragile both mentally and physically, she is not in critical condition. (Yonhap)