Liam Johnston died on Thursday morning and 12 firefighters were needed to transport him.
They also had to remove part of a door and fence panels from his home in Livingston, West Lothian.
Mr Johnston was 21 stone at the age of 18, but this had almost doubled to 40 stone by the time he was 21.
His post-mortem found that his final weight was 66 stone, one of the highest ever recorded.
Mr Johnston spoke in an interview nine months ago about how he wanted help.
He said: “I’m trying to get rid of this weight once and for all. I don’t want to put my family through the ridicule. I’m doing my best to sort my life out.
“I’ve hid myself away from the outside world, ashamed at the size I had become. You’ve no idea how difficult it is to go through something like that. To know that no one was there to talk to, for well over a year,” reported the Daily Mail.
Mr Johnston would rarely leave his home and only saw family.
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A Police Scotland spokesman said: “We can confirm that officers were called to assist the Ambulance and Fire Services at an address in Livingston where a 22-year-old man was taken ill on Thursday morning.
“A report surrounding the circumstances of his death – which are not being treated as suspicious – will be sent to the Procurator Fiscal at Livingston. His next of kin has been notified.”
Mr Johnston went to court last year after ordering four pizza meals worth £30 using stolen credit card details.
He said: “I felt disgusted with myself. I had shamed myself and my family.”
He was ordered to pay the money back to Dominos Pizza in Bathgate.
Yesterday, at her home in Livingston, his mother, Mary, 41, who also has a daughter, Allana, 20, was too upset to speak of her son’s death.
More than a quarter of adults in Britain are obese and it is estimated that this could reach as many as half by 2050.