Human beings have been getting remarkably fat since prehistoric times (to judge by such artifacts as the celebrated Venus of Willendorf), and accurate weighing is mostly a twentieth-century phenomenon, so the heaviest man or woman ever must always remain a matter of conjecture. Every age and culture has a tale of some remarkable heavyweight, but how much these Paul Bunyans of bulk have grown in the telling is impossible to say. A few such stories have come down to us from classical times. The Roman physician Galen, writing in the first century, cites the case of one Nichomachus of Smyrna, who was so heavy that he could neither move nor be moved from his bed. Other authors tell of a Roman senator who was able to walk only when two slaves carried his belly for him, and of a latter-day Egyptian pharaoh whose belly was broader than the span of a man's outstretched arms.
You can read the sad stories of the 10 World's Heaviest People, Most of whom have been exploited by other people, with the promise of getting help. Only to have people like jerry Springer do nothing after making his money.