By 2000, when Dunkin' Donuts celebrated its 50th anniversary and opened its 5,000th outlet in a chain spanning the U.S. and 37 other countries, Rosenberg was curtailing his own intake of its baked products because of weight problems and diabetes. But he continued to have a cup of the chain's fresh coffee every morning, and he served the doughnuts in his home, joking that, when nobody was looking, he could inhale two dozen.