Blair River was the 6-foot-8, 575 pound, 29-year-old spokesman for the hospital-themed Chandler restaurant, which prides itself on selling "Quadruple Bypass" hamburgers, "Flatliner Fries" cooked in lard, unfiltered cigarettes, and alcoholic beverages, among other "treats."
River contracted pneumonia after he was in a hospital for four days with the flu earlier in the week, but his exact cause of death is yet unknown.
ABC News reports that River's obesity could have placed him at an increased risk for nearly every acute health problem.
In 2010, River was hired to be the Heart Attack Grill spokesperson at a rate of $100 per hour.
His first YouTube video for the eatery offered anyone weighing more than 350 pounds a free meal.
River apparently was the brains behind several of the promotion techniques from the restaurant, and was even planning a musical relating to the restaurant.