Jessica Simpson Reveals She Took Diet Pills for 2 Decades Starting at Age 17

Jessica Simpson is opening up about her struggle with body image and 20-year addiction to diet pills in her upcoming memoir, Open Book, revealing in an excerpt shared by PEOPLE this week that she first started taking the potentially harmful pills after being told on her 17th birthday by Tommy Mottola at Columbia Records, "You gotta lose 15 pounds."

"That's what it will take to be Jessica Simpson," he told her, Simpson recounts in the book.

At the time, the 5'3" singer weighed 118 lbs. but "immediately went on an extremely strict diet" and started taking diet pills, which she said would be normal for her over the next 20 years.

As her career took off and pressure mounted, Simpson remembers, "I started to hear voices when I was alone at night, waiting for the sleeping pill to kick in...'Do more sit-ups, fat a--.'"

With Simpson's weight fluctuations becoming common fodder in the tabloids as she grew in fame, she recalls, "We all see our flaws, and mine were just there for the world to rip apart. They weren't even flaws! They were made into flaws that I didn't even know I had. It's insane what can make a headline."

At more than two years sober now, Simpson said she's found acceptance and love for herself and her body.

"When I work out, a lot of it is to release anxiety -- that's one of my tools for sobriety," she says. "Just going walking and talking with my husband."

With conversations about body positivity becoming the norm nowadays, Simpson said she's happy her daughters, 7-year-old Maxwell and 10-month-old Birdie, are growing up in a different world than she did.

"I just thank God that times are changing and people are standing up for themselves and not making it about body image," she writes. "I hope I can be part of that change and that my daughters will grow up in a world where they can accept themselves at any size."

Naming Lizzo and Ashley Graham as role models of women who embrace their bodies and encourage others to do the same at any said, Simpson writes, "I'm happy they are able to be there for women. Growing up, we all looked up to fashion models on the cover of magazines. Now that fashion models are plus-size, that is a beautiful thing. I think it's important as a public figure to show that you're just like the person who lives next door."

Photo credit: Getty / Raymond Hall