John Brower Minnoch (1941-1983) of Bainbridge Island, Washington, weighed 976 pounds (443 kilograms) in 1976 and was estimated to have weighed more than 1,387 pounds (630 kilograms) when he was rushed to hospital in 1978 with heart and respiratory failure. Much of his weight was due to fluid retention. After two years on a hospital diet, he was discharged at 476 pounds (216 pounds). He had to be readmitted, however, after reportedly gaining 197 pounds (87 kilograms) in seven days. In 1983 when he died, he weighed 798 pounds (362 kg).

Source: The Handy Science Answer Book