Everyone knows the camera adds 10 pounds. But apparently if you stand next to Calista Flockhart it adds something like 50. Now actress -- and former ''Ally McBeal'' costar -- Courtney Thorne-Smith is following up a Self magazine story she wrote last fall about the pressures of being photographed next to, as she put it, ''extraordinarily petite female leads.'' Her as yet untitled book will be ''about finding the plan that works for you,'' says Hyperion editor Jennifer Lang.
