Aug. 3, 2007 — -- She was the enchanting little girl adopted into a life of luxury and indulgence by Lionel Richie.
She thrived in her privileged surroundings, playing classical piano and figure skating competitively. Then Nicole Richie hit her teens and skidded out of control.
There were early bouts with cocaine, heroin and recently, the prescription drug Vicodin. The image of her emaciated body dominated the tabloids, sending a message to young girls that her body and lifestyle were the epitome of glamour.
Watch Nicole Richie's exclusive interview with Diane Sawyer tonight on "20/20" at 10 p.m. EDT
Richie said that she now understands the consequences of being a public figure and that she was sending a negative message to impressionable young girls. "I'm really sorry for not accepting that earlier. It just — it took me a while."
While Richie apologizes for the message her thin body sent, she denies ever struggling with an eating disorder.
"No, I do not have an eating disorder. I've never had an eating disorder, ever," Richie said. "It's anxiety, it's stress, it's just — it's just not being careful."
Richie's much-hyped weight loss is now still an issue, not just for her, but for her unborn child.
She admits to having been self-destructive, careless and reckless, explaining that her extreme weight loss may have happened in conjunction with her drug problem.
That problem, Richie says, is now behind her.
"I eat all the time, especially now. I'm constantly hungry. I'm eating at least every hour," she said. "And just like any mother, you want to take the best care of yourself, especially while you're pregnant. I'm definitely eating healthier now."
She's been playing by the rules — no caffeine, no sushi, no alcohol or drugs. Even her boyfriend, Good Charlotte's Joel Madden, the baby's father, has quit smoking.
"I had to quit smoking and I was a smoker, a pack and a half a day. That was hard. That was a rough week," Madden said.
With pregnancy comes weight gain and Richie says she's prepared for it, saying she has already gained 10 pounds.
"It's what my baby needs and to me, numbers don't mean anything. If I gain 40 pounds, if I gain 50 pounds, then that's obviously what my body needs to do. I'm totally OK with that," she said.
Madden and Richie say they're just two people ready for the next chapter of life.
Richie said she recognizes her errors of the past and is dedicated to changing her ways.
"I'm here now and you know I can only control the future. I can't change the past. And you know, I plan to live a very healthy and respectable life and be a good example for little girls that are looking up to me."