She was born Jean Evelyn Slutsky in Brooklyn on Oct. 12, 1923, the daughter of David and Mae Rodin Slutsky. Her father was a cabdriver and her mother a manicurist. Jean and her younger sister, Helen, grew up chubby, and struggled physically and emotionally to control their weight problems. But Jean was a talker and popular in a circle of overweight friends. She graduated from Girls High School in Brooklyn, and joined the Internal Revenue Service as a clerk in 1942. In 1947, after a two-year courtship largely spent gourmandising, she married Mortimer Nidetch. They had two children, David and Richard. Richard died in 2006. The marriage ended in divorce in 1971. She was married again, for a few months, to a bass player she met on a cruise in 1975. Survivors include her son, David, and three grandchildren. After several years in Tulsa and Warren, Pa., the Nidetchs settled in a modest apartment in Little Neck, Queens, in 1952 and Mortimer became an airport bus driver. Mrs. Nidetch raised funds for charitable groups, including the North Hills League for Retarded Children, and was its president for two years. In October 1962, Mrs. Nidetch reached her goal of 142 pounds, and vowed to undertake a mission to help others lose weight. With Felice and Albert Lippert, an overweight couple she had helped, she and her husband formed a corporation, and Weight Watchers was born in a loft over a movie theater in Little Neck in May 1963. The business boomed. Hundreds of franchises were organized around the world. By 1968, five million people had enrolled. Mr. Lippert handled the business, and Mrs. Nidetch was its public image. Weight Watchers went public in 1968, turning its founders into multimillionaires, and in 1978 the company was sold to H.J. Heinz for $71.2 million. Mrs. Nidetch, who had been president in its early years, was in charge of public relations until 1984, traveling widely and making public appearances for Weight Watchers International, one of the world’s most successful weight-loss businesses. Mrs. Nidetch established scholarship programs at the University of California at Los Angeles and the University of Nevada. In 2006, she moved to Florida to be near her son, David.