42-year-old Mexican Manual Uribe, weighed 570 kilograms before starting to diet.
He is currently 325 kilograms, but is determined to slim down to around 120 kilos by 2010.
If he succeeds, he will beat the weight-loss record held by American Rosalie Bradford, who lost 333 kilograms in the early 1990s.
Mr Uribe had to live in a reinforced bed for the last six years, being looked after by his mother and fiancée.
But two years ago he started cutting junk food out of his diet, with the help of a US doctor, opting instead for fruit, vegetables, fish, chicken and omelettes.
Mr Uribe says he reached his original record-breaking weight in the US where he worked as a computer repairman, eating pizzas, burgers, chips and soda.
After returning to Mexico, he only added to his weight by eating tacos and fried food.
But since starting his diet, Mr Uribe has shed over 200 kilograms and even knocked-back an offer of gastric bypass surgery, because he wanted to lose the weight through health living.