He died of heart failure because he didn't listen to his doc when he told him to lose about 20 pounds.
here is a bit more for you.....
Hill's health began to decline in the early 1990s. Weighing 238 lbs (108 kg) at 5 feet 10½ inches (1 m 79 cm) tall, he suffered heart problems related to his obesity. On February 11th, 1992, doctors told him that he needed to lose 28 pounds, and recommended a heart bypass. He declined, and was diagnosed a week later with renal failure.
Benny Hill died on or about 20 April 1992 (Easter weekend), alone in his flat at 7 Fairwater House, Twickenham Road, Teddington, at the age of 68. On 24 April, concerned neighbours had called the police, who then found the deceased Hill sitting in his armchair in front of the television. On the day that Benny Hill died, a new contract arrived in the post to him from Central Independent Television.
The cause of death was listed as coronary thrombosis. (His death closely coincided with that of another British comedy icon, Frankie Howerd, who died on 19 April aged 75.)