Janet Jackson on Paris Joining the Family Business, Her Life-Long Weight Battle and Conrad Murray's Conviction

Dec. 15, 2011— -- No one understands the dark side of fame better than the Jackson family, and as a new generation of Jacksons seeks the spotlight, Janet Jackson said she cautioned her niece about joining the family business.

In her first interview since Michael Jackson's physician, Dr. Conrad Murray, was convicted of involuntary manslaughter in Jackson's 2009 death, Janet Jackson talked about her feelings on Michael's daughter, 13-year-old Paris Jackson, signing on to do her first movie.

"I'm happy for her," Jackson said with a knowing sigh. "I told her, I said, 'You should really take your time to enjoy your youth to the upmost, to the fullest, and enjoy that.' She wants to really give it a go. I mean, you lose so much of your childhood in this industry."

Being a child star is something Aunt Janet is all too familiar with. While her decades-long music and acting career has brought her international fame, Jackson said the experience left her emotionally scarred for life. Even with abs of steel, Jackson said she has felt insecure about her body for years. Her newly released paperback, "True You: A Journey to Finding and Loving Yourself," shares her lifelong battle for self-acceptance.

"If it isn't our arms, it's our thighs, it's our butt, it's our stomach," she said. "I could easily pick myself apart. That's what I would do, that's what I did."

The youngest of nine children in a household that lived and breathed fame, Jackson said her body issues began when she was a little girl, and her older brother Michael would tease her about her body.

"It was about my butt being too big," Janet Jackson said. "I carried it with me through my adult life."

At age 8, Janet Jackson was already belting out tunes on "The Carol Burnett Show" and holding her own alongside her brothers, who made up the enormously popular Jackson 5. But the scrutiny she received about her body at a young age, not just from her brother but from television producers, she said fueled a bad self image.

"I was 10 when I did 'Good Times,'" Jackson recalled. "I remember them asking me, my first show, the wardrobe woman said, 'We are going to bind your chest.' I was developing at a very young age. Then the following season they told me I need to lose weight."

"I look back on those episodes and I go, 'Oh my gosh, I'm not a heavy kid by any means,'" she continued. "I internalized it and I never told anyone about it, and kept it inside for years."

While Jackson's anthem became "Control," the title track off of her third album, released in 1986, she said she felt anything but, and would often turn to snack food for comfort.

"Ice cream sandwiches, chips, cookies -- sometimes healthy food, but not much," she said.

By 2005, her weight had ballooned. Jackson's book "True You" details her painful journey that she said made her want to help others. In a surprising move, Jackson has now stepped out into a new role as a spokeswoman for Nutri-System.

"It has to be something I truly believe in," she said. "I have struggled. I have had issues with this all my life. I am not just someone speaking out about it or hired to endorse it. I lived it. I understand it."

Jackson completes the trio of other divas who have signed up to sell competing diets in the roughly $60 billion weight loss industry. Mariah Carey said she lost her baby weight after having twins with the Jenny Craig program. Broadway star Jennifer Hudson touts Weight Watchers, which is the brand leader in diet programs, followed by Nutri-System.

Visit Nutri-System's Facebook page for more information.

"I tasted the cheese puffs and, oh my gosh, and they are 8 grams of protein in cheese puffs?" Jackson said, adding that she understood the love-hate relationship that people can have with food. "You crave it at that moment and once you do it, you hate yourself and hate ... that you have gone there and done that."

Jackson said she is proud that the Nutri-System is committed to donating $10 million in food contributions to the hungry.

Still, research suggests 80 percent of most dieters re-gain the weight on national weight loss plans.

"It is a matter of learning how to keep it off," she said.

It has been a year of a "great deal of happiness, some sadness," Jackson said. In November, the Jacksons were forced to relive the trauma of Michael Jackson's death during the trial of Conrad Murray, who is serving a four-year sentence.

At the time of the conviction, Janet Jackson posted on Twitter, "justice has been served," and she said not a day goes by that she doesn't think about her brother, Michael Jackson.

"Even though it doesn't bring my brother back -- that would be the ultimate -- but the best was done at that moment," she said. "It was difficult for all of us. It wasn't easy sitting there every single day."

But 2011 also has been Jackson's year of new beginnings. Aside from her new spokeswoman role, she has a deal to direct a new film project and an international concert tour. Jackson, who once collaborated with her brother Michael Jackson on many projects, said she wanted her brother's legacy to be how much he loved others.

"His love for children, his love for people, his love for music, his love for the fans -- just love, period," she said.

ABC's Lauren Effron contributed to this report.