Scientology. Kirstie Alley. Weight loss. A triumvirate of more exciting phrases is rarely uttered. Tuesday night, the former 'Cheers' star sat down with David Letterman to speak out on her famous struggle on the scales and to promote her upcoming reality show 'Kirstie Alley's Big Life.' "I think other people are stuggling with my weight more than I am," she told the host. But it was what the actress said Tuesday morning on 'The Today Show' that should get the headlines.