What is kind of sickness is this? and how can one prevent it?

MONTERREY, Mexico (AFP) - A Mexican tipping the scales at 560 kilograms (1,234 pounds) will be listed as the world's fattest man by the Guinness Book of Records, while a loss of 200 kilos (440 pounds) may make him the man who lost the most weight.
"I'm glad to be in the Guinness Book as the fattest man. I am also happy to have lost 200 kilos," Manuel Uribe, 41, told AFP.
Uribe was able to leave his home in Monterrey, northern Mexico in March aboard a trailer to celebrate his weight loss.
Guinness has recognized his weighty achievement with a glass plaque.
"They gave it to me, I have it in my hands," said Uribe, who founded an organization to help overweight people.
Uribe's photograph appears in the 2008 Guinness Book of Records alongside a description of the treatment he has had and offers of surgery he has received.
Uribe said the editor of the book had promised to visit him next year, and held out the possibility of appearing in the 2009 edition as the man who had lost the most weight.
Uribe appeared on television in 2006 seeking help for his excess weight, which has plagued him for more than 20 years, most of which he has spent in bed.