Paul Mason, 48, of Ipswich, England, who recently said he requires emergency surgery to reduce his weight, was sent to jail in 1990, when he weighed 420 pounds, and lost 140 pounds during his year of incarceration, The Daily Telegraph reported Friday.
Mason was in Norwich Prison for stealing cash from mail while working as a mail carrier.
"There were no fish-and-chip suppers or Chinese takeaways in prison," his sister, Louise, 43, told the newspaper The Sun. "He got down to about 20 stone (280 pounds) -- it was unbelievable. But that's because he had no option but to eat healthily,"