In a new interview with People magazine, Williams, 50, reveals her battles in the past with weight and drugs.
"Drugs were a demon I had to overcome," Williams told the magazine of a 10-year span where she used cocaine.
Williams, who is now 5-foot-11 and 165 pounds and loves her body, said she started to diet because of peer pressure at a young age.
"My life before 21 sucked," she added. "My first diet was in the first-grade! Tuna fish and mustard with yogurt on the side."
She continued, "In high school I was just the girl standing on the side, looking at everybody having fun and saying, 'I can't wait to get out of here and set the world on fire.' "
Williams, who now has a 14-year-old son, Kevin, also said having a baby with her husband wasn't smooth either.
"There was a hiccup with a couple of miscarriages," she said. "Life is hard on us women."