Jennifer Lawrence said she was ordered to take part in a nude line-up - and then told to use the pictures as weight loss inspiration - as she opened up on her "degrading" experiences as a young actress.
The Oscar-winning star said she was subjected to the "humiliating" review as she tried to break into Hollywood.
When she complained to a male film executive, he replied that he didn't understand the concerns over her weight as she "perfectly f***able".
Lawrence shared her experience as she addressed the allegations of sexual harassment and rape against Harvey Weinstein in an appearance at the Elle Women In Hollywood Awards in Los Angeles.
She told the audience at the event that she found the allegations against the movie mogul "harrowing", before recounting her own story.
The 27-year-old said she was told to "lose 15lb" in two weeks when she was "much younger and starting out".
One girl "had already been fired for not losing enough weight fast enough" she said of the unnamed film project.
Lawrence said she had felt powerless to speak out about abusive and sexist behaviour earlier in her career.
It was only after her status as a major star was cemented by her role as Katniss Everdeen in the hugely popular Hunger Games franchise that she had "the power to say no", she said.
"I let myself be treated a certain way because I felt like I had to for my career," she said.
At the same event, Reese Witherspoon said she had been harassed and sexually assaulted throughout her career.
She said she felt "true disgust" at the director who assaulted her when she was 16 as well as anger at the agents and producers "who made me feel that silence was a condition of my employment".
"And I wish I could tell you that that was an isolated incident in my career, but sadly it wasn't," she added.
"I've had multiple experiences of harassment and sexual assault, and I don't speak about them very often, but after hearing all the stories these past few day sand hearing these brave women speak up tonight, the things that we're kind of told to sweep under the rug and not talk about, it's made me want to speak up and speak up loudly, because I felt less alone this week than I've ever felt in my entire career."
The growing flood of accusations against Weinstein - and claims that many around him abetted or ignored his behaviour - have led to a wider conversation about sexism within Hollywood.
A number of actresses have come forward in recent days to accuse Weinstein of sexual harassment, including Gwyneth Paltrow, Angelina Jolie, Cara Delevingne, Rose McGowan and Ashley Judd.
Three women have also alleged that Weinstein had raped them in an article in The New Yorker - claims that have been vehemently denied by Weinstein.