Chinese weightlifter Long Qingquan lifted a world record combined total of 307 kg to take Olympic gold in the men s 56-kg category in Rio on Sunday.
Turkey's Halil Mutulu had set the previous world record total of 305kg at Sydney 2000, and defending champion Om fell just two kilos short of that score himself in finishing second.
Om, who stands at only 1.5 meters, has won three straight world championships since taking London by storm four years ago.
In the snatch segment, Beijing 2008 victor Long matched the 16-year-old Olympic record of 137kg.
The pressure was back on the Chinese lifter, but he responded with a second effort of 166kg to move ahead by five kilograms, and Om, under even greater pressure, found the Olympic record weight of 169kg too much for him as his legs wobbled and buckled under duress.
"I am really happy". "I'm disappointed and there's nothing more I can really say about it", a dejected Om told reporters when asked about the end of his long reign at the top. I came to this competition with two dreams: "to win the competition and break the world record and I did both", Long said after winning on Sunday. "With the help of my family I made it through", he said.
The 2008 Summer Olympic gold medalist produced a spectacular display to get the better of the reigning titleholder Om Yun Chaol of the Democratic People's Republic of Korea. "I was still a boy eight years ago".
"I'd like dedicate this medal to my baby who is going to be born soon", he said, smiling.
Olympic rookie Sinphet Kruaithong finished a relatively distant third, posting a total of 289kg.