Simpson got hooked on to diet pills at the age of 17 after she was ordered to lose weight by record executive Tommy Mottola.
Simpson dropped to 46.72 kg (103 lbs) after she was told to shed 15 lbs (6.80389 kg) in order to get signed to a record label, she said in excerpts of her new memoir "Open Book", obtained by People, reports aceshowbiz.com.
On her 17th birthday, Simpson had the chance to sing for Mottola, who at the time was the CEO and chairman of Sony Music Entertainment, parent of the Columbia label, and belted out "Amazing Grace" in a bid to get snapped up and signed to their roster.
Simpson said that "he wanted to sign me", but he said: "You gotta lose fifteen pounds."
After questioning his remark, he reportedly told her: "That's what it takes to be Jessica Simpson."
She said that at the time she was five-foot-three and weighed 53.5 kg (118 lbs). After the meeting, she "immediately went on a strict diet, and started taking diet pills, which I would do for the next twenty years."
She said that she also took sleeping pills at this time, noting: "I started hearing voices when I was alone at night, waiting for the sleeping pill to kick in 'Do more sit-ups, fat a*s."
She notes she "couldn't enjoy" her success "because I was so freaking hungry" and said that after she lost weight, the label reportedly told her "show more skin" which sent her on more of a downward spiral.
( With inputs from IANS )