London, Dec. 7 (PTI): A 444.5kg British man, believed to the fattest man in the world has died.

Keith Martin, 44, died from pneumonia following a lengthy battle with his weight.

The death happened just eight months after Martin underwent a successful gastric sleeve surgery, which removed three-quarters of his stomach, The Daily Telegraph reported.

If he had lived, he would have lost hundreds of pounds and regained his ability to walk and live a normal life, according to head surgeon Kesava Mannur who operated on Martin last year.

Mannur supported new guidelines which encourage doctors to suggest weight-loss surgery for anyone with a BMI over 30 and type 2 diabetes.