Even though Jennifer Hudson has dropped more than 36 kilogrammes, the singer and actress said she would have no problem gaining weight for Hollywood if the proper movie role comes her way.

"When I do films, it has to be led by something through me - like my passion for it," Jennifer said before a book signing in Atlanta. "I just don't want to hop into anything. So if I commit myself to something, then it'll be worth it no matter what character it is."

Last week, Jennifer released her book, I Got This: How I Changed My Ways And Lost What Weighed Me Down. The book touches on how she dealt with her weight issues throughout her career before she lost the extra pounds.

In it, Jennifer - who is both a Grammy and Oscar winner - also talked about how she turned down the lead role in the 2009 film Precious. The role ended up going to Gabourey Sidibe, who was nominated for an Oscar for playing an obese 16-year-old girl who had an abusive mother, an incestuous father and faced extreme poverty.

"I felt it was too graphic for me at the time," she said. "It's something I didn't want to do at the time, but I would gain weight in a heartbeat. I have no issues with that at all."

Jennifer is a spokeswoman for WeightWatchers and wants to remain physically fit along with her fiance David Otunga, who has recently been wrestling for World Wrestling Entertainment. They both want to set an example for their two-year-old son.

"We really didn't realise how important health was until we were adults," she said. "We wanted to make sure we set an example for our son. He's health conscious, and I am health conscious."