Mexico City: A Mexican man once regarded as the world's most obese has died of heart failure at the age of 38, two months after bariatric surgery to lose weight.

Andres Moreno Sepulveda, who had weighed as much as 450 kilograms, died en route to hospital in the northwestern state of Sonora on Christmas Day, a friend told DPA.

A still from a YouTube video showing Sepulveda before surgery in October. Credit:Screengrab

"He was doing well, but he had had two previous heart attacks. He became short of breath, and died in the ambulance," said Carmen Palacios, who had been helping him during his rehabilitation process over the past year.

The former police officer had been confined to a bed for four years. He had slimmed down to 320kg before undergoing gastric bypass surgery to reduce his stomach.

His doctor said following the procedure that they hoped to get him down to about 85kg eventually.

DPA