Harold Katz, the founder of the first Nutrisystem center in Willow Grove and a former owner of the 76ers, died on Friday, January 24. He was 87. According to his obituary in The Philadelphia Inquirer, Mr. Katz invested $20,000 to open the first Nutrisystem center in Willow Grove in 1972 and went on to create the Nutrisystem franchise. By the time he sold it in 1986, the business had grown to become the nation’s largest medically supervised weight control company…