Experimenting in their own kitchen, he and his wife devised recipes and menus, writing the best-selling cookbook and guide "Eat Well and Stay Well." They followed that with "The Benevolent Bean" in 1967 and "How to Eat Well and Stay Well the Mediterranean Way" in 1975.
The couple used their royalties to buy a home on the coast of southern Italy, where they could easily maintain their recommended diet.
Keys, 5 feet 7 and 155 pounds, practiced what he preached. Nevertheless, given his lack of confidence in anecdotal evidence, he was reluctant to attribute his own longevity to his diet.
"Very likely," he told the news media at his 100th birthday last Jan. 26. "But no proof."
Born in Colorado Springs, Colo., and the nephew of actor Lon Chaney, Keys grew up in Berkeley and demonstrated a proclivity for science early in life. He was given a chemistry set on his 8th birthday, which led to an uncharacteristic experimental failure: Trying to chloroform a fly, he keeled over.