In the introduction of her new book, "I Got This," Jennifer Hudson writes that she had always dreamed of someday walking the red carpet in Hollywood.

"Jennifer! Over here! Jennifer, look this way," imaginary paparazzi would yell as they snapped her picture, she fantasized as a teen.

The singer and actress turned that dream into a reality after her 2004 appearance on "American Idol." Hudson was just 22 at the time.

Hudson did not win "American Idol's" third season finale. She finished in seventh place. But the voluptuous newcomer from Chicago, Illinois turned industry heads with her big, soulful voice and powerful mezzo-soprano range.

Thanks to such raw talent, Hudson landed the role of Effie White in the 2006 film adaption of the musical "Dreamgirls," and went on to win a Best Supporting Actress Oscar for her impressive film debut. Hudson also won a Grammy for her 2008 album, "Jennifer Hudson," which sold more than one million copies worldwide.

But the road to stardom was not easy, as 30-year-old Hudson writes in "I Got This: How I Changed My Ways and Lost What Weighed Me Down."

"It's pretty much my story of life and the weight battles," Hudson told CTV's Canada AM from New York, in an interview that aired Tuesday.

"I figured why not put it in word form and maybe inspire people along the way in their journey," said Hudson.

Since her rise to fame, Hudson's career has been derailed at times by life changes and tragedy.

On October 24, 2008, Hudson's 57-year-old mother, Darnell Donnerson, and the singer's 29-year-old brother, Jason, were found shot to death inside the Chicago home that Donnerson shared with Hudson's elder sister, Julia.

On a happier note, Hudson became a first-time mother in 2009, giving birth to a boy named David Daniel Otunga Jr.

But Hudson's battle with weight and with an industry that places image above talent is the theme that dominates this book.

The 5-foot-9 star has lost 80 pounds, slimming down from a size 16 to a size 6 over the last two years.

Hudson made this physical transformation by following Weight Watchers. She also became the company's spokeswoman two years ago.

Like many women, Hudson struggled to lose weight after her pregnancy.

"While I was in my third trimester of being pregnant, I was like ‘Wow. You want your body back. You miss just being your old self," said Hudson.

During that time, Hudson also came to the brutal realization that no one knew she was pregnant.

"That was a red flag," said Hudson.

At the moment, Hudson made the decision to get a hold of her eating habits and lose the baby weight.

"It was a matter of making up my mind and doing what I wanted to do with myself. That's what I did," said Hudson.

Career longevity also played its part in Hudson's decision to slim down.

According to Hudson, she heard, indirectly, a rather brutal assessment of her career prospects issued by legendary record producer Clive Davis. Davis had said that Hudson would never be a star without dropping the extra weight.

"It didn't come through directly, but I got the message," said Hudson.

That message about her image came as no big surprise.

"That's the nature of the business," said Hudson.

"I was determined to make it off of my talent, which I was able to do. For me, it should have been -- and it has always been -- about the talent. I didn't care what people thought or what I looked like. I wanted you to hear me. I wanted you to see my talent," she said.

"When I heard, ‘Image, image, image,' it was like, ‘Okay. Why does this matter? I couldn't understand it at all."

Hudson's remarkable physical transformation has landed her on talk shows in recent months and on the covers of tabloids.

Earlier this month, Hudson expressed her outrage when a publication altered images of her to appear thinner than she was -- despite her 80-lb weight loss. Hudson felt that the move sent out the wrong message to her fans.

Despite the big changes to her looks and her life, Hudson still holds on to one mantra: "If it's meant for me it will be."

"My mother always said, ‘All you can do is the best you can do,'" said Hudson.

"On ‘American Idol,' I got a chance to display my talent. I was satisfied with that," she said.

That focus kept Hudson steady as she shot "Dreamgirls," and people around her were predicting she'd win an Oscar.

"I didn't get it at all," said Hudson.

"I had no idea how important Effie was while I was portraying her. Sometimes it's good to be blinded to things. That way you can focus and not have the jitters and nerves," she said.