A Mexican man, once touted as the world's heaviest at 600kg, has gone under the knife to lose weight. Juan Pedro Franco successfully underwent a gastric bypass surgery, which was intended to reduce his weight by half, and is under observation.

"The surgery was quite successful. But now we have to wait and see how he responds to the (systemic) change. Let's hope everything goes well," his surgeon Jose Castaneda said on Tuesday, 9 May. If all went well, Franco would have to undergo another surgery, which will focus on his stomach's size and modification of his intestines.

Before surgery, Franco was told to lose a large amount of his initial mass to avoid complications during the process. He was also asked to get his diabetes and blood pressure under control in order to be eligible for surgery.

Franco, who was bedridden for several years, followed a strict diet regimen and instructions, before he got the nod for his weight-loss surgery.

The process has left Franco "quite delicate", Castaneda said and warned "the entire thing will fail" if the patient failed to progress on the psychological and nutritional fronts.

The case of Franco is similar to the story of Egyptian Eman Ahmed Abd El Aty, who also underwent gastric bypass surgery at an Indian hospital under the supervision of surgeon Dr Muffazal Lakdawala.

Abd El Aty, once believed to be the world's heaviest woman at 500kg, now weighs 172kg. She is currently at Burjeel Hospital in Abu Dhabi and is expected to receive a year-long treatment there.

World's heaviest man to have bypass surgery to save life
Juan Pedro Franco is believed to be the heaviest man in the world Reuters