Manuel Uribe, from Monterrey, was awarded the Guinness World Records title of heaviest man - living in January 2006, after making a television appeal for help with his condition.
At that time Manuel weighed 560 kg.
After receiving medical assistance following his TV appearance, Manuel slowly started to lose weight and by 2007 was reported to have lessened to 381 kg.
Nevertheless, he remained morbidly obese and was unable to stand up on his own, having been bed-ridden since 2002.
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The spokesperson went on to confirm that Manuel had been taken to hospital earlier this month because of an abnormal heartbeat. Doctors have yet to confirm the cause of death.
Craig Glenday, Guinness World Records Editor-in-Chief, said: "I had the pleasure of meeting with Manuel at his home in Monterrey when he first agreed to be weighed. Despite being bed-bound, he had a redoubtable spirit and vowed to do all he could to lose his world record status.
"Although his record remained unchallenged, it was inspiring to see him succeeding in his subsequent weight-loss efforts and face his challenges with a smile. He'll be a much-missed member of the Guinness World Records family," Glenday said.