Friends of Blair River, who became spokesman for the Chandler restaurant last year, said the cause of death is currently unknown but he recently fell ill with pneumonia after contracting the flu, The Arizona Republic reported Friday.
Jon Basso, founder of the Heart Attack Grill, which bills itself as celebrating the "glorification of obesity," said he first got to know River as a customer before he was hired as spokesman.
"Cynical people might think this (River's death) is funny," Basso said. "But people who knew him are crying their eyes out. There is a lot of mourning going on around here. You couldn't have found a better person."
River, who lived in Mesa, worked as a financial adviser at the University of Phoenix. He played football for Mesa Community College after being declared the 1999 state heavyweight wrestling champion when he was a senior at Payson High School.