A man believed to be the world's most obese passed away on Friday in Mexico, barely two months after undergoing a weight-loss surgery.

Andres Moreno, 38, died of a heart attack and peritonitis (inflammation of the abdominal lining) in Ciudad Obregon, in Sonora state, his family said.

Moreno, who at one time tipped the scales at 450 kilos, had bariatric surgery on October 28, in Guadalajara, Jalisco state, in hopes of shedding the excess weight and leading a normal life, Xinhua news agency reported.

The surgery involved removing three-fourths of his stomach and reshaping what was left into a tube to "prevent him from eating too much", the Medical Daily reported in October.

While the operation was considered a success, the ex-policeman complained of feeling ill on Christmas Eve, "and his family called on firefighters to help stabilize him", state news agency Notimex reported.

Early on Christmas Day, he was having difficulty in breathing and family members decided to have him taken to the hospital in an ambulance, but he died on the way.

The "Most Obese Man in the World" had shed 100 kilos to be able to undergo the surgical procedure in October.

On November 19, Moreno had emergency surgery at the local State General Hospital (HGE) in Ciudad Obregon, due to severe peritonitis.

He then returned to Guadalajara to convalesce under the supervision of the same medical team as before, and had returned home a few days ago, Notimex said.