You've watched the one you love take up channel surfing as a sport and set world records on eating the sport's official snack foods: Doritos and Ho Hos. You know it's unhealthy, but it's a sensitive issue and you don't want to hurt anyone's feelings. "You can't make someone change if they're not ready to," says James Rosen, Ph.D., professor of psychology at the University of Vermont, and the director of the university's Weight Control Program, "but you might be able to help motivate them." How do you drop the hint that it's time to drop some pounds? Rosen offers some advice…