Janet Jackson

R&B singer Janet Jackson, who packed on over 50 pounds last year, is writing a book on how she lost it all. "I'm writing a book on my journey of weight loss and weight gain," Jackson, 41, told PEOPLE. "[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, who gained 60 pounds last year, says 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." Currently dating music producer Jermaine Dupri, two times 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."