Actress Kirstie Alley has a no-holds-barred conversation with Larry King about weight, fame, success and failure in Hollywood. Watch "Larry King Live," tonight, 9 ET.
Los Angeles, California (CNN) -- Kirstie Alley describes herself as "that fat actress who gained weight and then lost it, and then gained it again."
The former "Cheers" star told CNN's Larry King, in an interview to air Thursday, that she's "really hard-headed," so it always takes her two times to kick a bad habit.
Alley is promoting a new diet that she said she created with "greatest scientific minds on the planet" and a TV reality show about her struggles with her weight.
She overcame a cocaine addiction in 1979 on her second try, she said.
"It's the same with cigarettes," she said. "I quit smoking a couple of times. Now I haven't smoked for five years."
Alley stepped into controversy Tuesday when she was asked on NBC's "Today Show" if her diet program, Organic Liaison, was aligned with the Church of Scientology.
She denied a connection, but she told King that Scientology, her faith for three decades, has helped her lose weight.
"Oh, yes, God knows what I'd be if I hadn't changed the things that I have changed," she said.
The 59-year-old actress said she's been overweight for only three years of her life, starting when she was 55.
Her first major weight loss happened after she became the celebrity spokeswoman for Jenny Craig in 2005.
"Kirstie Alley's Big Life," which debuts Sunday night on A&E Network, is her second television series about her obesity.
She also starred in the scripted series "Fat Actress," which lasted for just one season in 2005 on Showtime.