She recently signed on as the new face of Weight Watchers and Jennifer Hudson could not have been a better advertisement as she paraded around Cannes Film Festival over the weekend.

The 28-year-old, who won an Academy Award in 2007 for her role in Dreamgirls, showcased her slim figure in a series of stylish frocks while promoting her upcoming biopic about Winnie Mandela. She followed the diet programme for several months after she gave birth to her first child, David Jr, last August. She put the impressive results on show in a thigh-skimming pale gold dress, a stylish cobalt blue number and a navy shift dress while attending a variety of events at the Festival.

She is now gearing up to fly to South Africa with Terrence Howard, who will play the former South African president alongside her, where filming will begin on May 31. Jennifer, who rose to fame on American Idol in 2004, said: "I am so excited and so honoured and can't wait to get started. We start in the next week and I'm ready to go to Africa for the first time." But Ms Madikizela-Mandela, as she has been known since her divorce, is understood to be unhappy about the biopic, which is based on Anne Marie du Preez Bezdrob's biography, Winnie Mandela: A Life.

A spokeswoman for the film said its producer André Pieterse and director Darrell Roodt had met lawyers representing Ms Madikizela-Mandela and had refused to give her script approval because they wanted to preserve the integrity of the film. Jennifer insists the film will let movie-goers make up their own minds about the controversial figure. Jennifer, whose mother, brother, and nephew were tragically killed in a shooting in 2008, is also preparing to marry her fiancé David Otunga.