Janet Jackson arrives during the opening day of Dr. Conrad Murray's trial in the death of pop star Michael Jackson in Los Angeles
Janet Jackson arrives during the opening day of Dr. Conrad Murray's trial in the death of pop star Michael Jackson in Los Angeles September 27, 2011. Reuters

It's no secret that Janet Jackson has battled weight issues her entire life, but what her fans may not know is that even when the singer is on tour, sweating every night, she still has problems staying slim.

So Jackson joined the ranks of Nutrisystem users on Thursday to become the new face of the weight-loss program, promoting a new SUCCESS diet plan even as she uses it to help raise money to feed the world's hungry.

The Rhythm Nation singer and member of the famous Jackson family, wrote fearlessly about self-image issues in her book, True You, documenting a period in 2006 when she put on weight for a movie and ballooned to 180 lbs, only to become fodder for fat jokes in the tabloid press.

But Jackson said it's not only working as an actress that can cause her to put on pounds. Rather, it is everyday life that gets her. And even after dancing and singing nearly every night on her Number Ones, she still battles weight gain.

Your body gets used to different exercises, and I've been performing for so long that my body's just used to it. Actually, I have to work a little harder while doing a show, she told Reuters.

Weight gain, she said is something I've dealt with my entire life.

In her book True You, which was published in hardcover earlier this year and hit stores in paperback this week, Jackson writes eating was emotional for me; eating calmed my nerves and brought me instant gratification.

After Nutrisystem chief executive Joe Redling read the book, he approached Jackson about his weight-loss program and gave her some of Nutrisystem's pre-packaged foods to sample while on tour. Jackson said she was sold.

When I was in hair and makeup, we were all taste testing. Everybody was going crazy for it, she said.

LOVE THE CHEESE PUFFS

When asked her favorite Nutrisystem meal, Jackson said I can't say there's just one thing, then she paused.

They do have cheese puffs, she said. It had been years since I wrapped my lips around cheese puffs because they were things I had to stay away from.

Jackson joins a long list of celebrities, including Kirstie Alley and Jennifer Hudson, who have publicly battled weight loss and endorsed diet programs. Typically, the stars document how much they lose, but Jackson doesn't want to do that.

I'm going about this a different way by not putting a pound amount on it, she said. It's about when I feel healthy, about when I feel good. That is how I want to be, she said.

Like most people, she pops her meals into a microwave to heat them up, but is quick to add that, unlike many others, she has a trainer to help her work out. She stresses the importance of exercise, but emphasizes that people don't need a trainer when all they really need to do is go for a long walk or do other everyday activities that get them off their couches.

Key to Jackson's involvement in Nutrisystem, she said, is that for every pound its dieters loose in 2012, the company will donate $1 worth of food to people in need. The pair have created Nutribank, (www.nutribank.org ), to work with hunger organizations around the world. Last year, Nutrisystem users lost 10 million pounds, in total.

I feel that my true calling is to help people, she said. Now, that calling extends to weight loss and quashing hunger.