“She was into healthy eating.” Prince William, Princess Diana, and Prince Harry on a skiing holiday in 1993Credit: GettyThe GistPrincess Diana was a health-conscious eater, but she liked to “spoil” Prince William and Prince Harry when they returned home from boarding school.There was one surprising food item that she only ate when her sons were around, according to her former chef.Royal chef Darren McGrady cooked for Diana from 1993 until her de…