"I’m writing a book on my journey of weight loss and weight gain," Jackson, 41, told PEOPLE at the Hollywood premiere of Tyler Perry's Why Did I Get Married?
"[I'm] really coming from the soul with it, and what I was going through at different times in my life and what possibly brought it about for myself," she says of the yet untitled book. She'll also include in the book what she did "nutrition-wise" to slim down "when she needed to," but warns, "It's different for everyone."
Jackson put on 60 lbs. last year and told Extra it had a debilitating effect on her. "I could not believe how big I was, how heavy I really was," she said. "I would see myself in the mirror, but I wouldn't look too often. I didn't want to get used to that image."
Jackson, who later held court at the afterparty at Boulevard 3, was looking fit but giving the outfit credit. "It's really the dress, I would say," Jackson said of the L'Wren Scott creation. "She just knows how to fit the right dress on a woman’s body, really. And she’s very good at what she does."
Third Time's the CharmCurrently dating music producer Jermaine Dupri, 34, twice-divorced Jackson hinted at the possibility of nuptials in their future.
"I've done it twice and divorced twice, and the next time I do it – if I do it – I really don't plan on divorcing," she said. "Oh, I pray this doesn't bite me in the butt ... saying this. But they say the third time is a charm."
If Jackson decides she's going to the chapel, again, it will be more for love than obligation. "Exchanging vows and finding your soul mate and coming from a more spiritual place is more of the way for me, for myself," she said. "I don’t necessarily need the paper to validate the love that I have for someone."
Reporting by JED DREBEN
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