The Dark Knight Rises actress was said to be on a 500-calories-a-day diet in order to portray a frail Fantine in the upcoming Les Misérables movie adaptation.
The diet would involve her eating only two apples a day in order to lose 16lb in less than 20 days, according to The Mirror.
However, her rep has dismissed the claims, explaining that the diet has been exaggerated.
"She is losing weight for the part, but not that much," her publicist said in a statement. "Just enough for her to look more frail, as she is playing a dying prostitute.
"She is consuming more than 500 calories. [The tabloids] are making something of nothing, as usual."
Hugh Jackman, Russell Crowe, Amanda Seyfried, Helena Bonham Carter and Sacha Baron Cohen will all feature in Les Misérables, which has started filming in Portsmouth.
Leading star Jackman recently posted the first official photo of himself as Jean Valjean on Twitter.
Les Misérables will be released in cinemas on December 14.
Anne Hathaway said in February that she has a lot in common with Lindsay Lohan.
Watch Anne Hathaway in the Dark Knight Rises trailer below: