The 27-year-old actress has opened up about the shocking lows she was subjected to when beginning her career, including forced to strip and stand next to "much, much thinner" other women in an attempt for her to be shamed into losing weight.
Speaking about her career at Elle's 2017 Women in Hollywood bash, which took place at the Four Seasons Hotel in Los Angeles, California, on Monday the 'Mother!' star said: "When I was much younger and starting out, I was told by producers of a film to lose 15 pounds in two weeks.
"During this time a female producer had me do a nude line-up with about five women who were much, much, thinner than me. We are stood side-by-side with only tape on covering our privates.
"After that degrading and humiliating line-up, the female producer told me I should use the naked photos of myself as inspiration for my diet.
"He said he didn't know why everyone thought I was so fat, he thought I was 'perfectly f***able.' I let myself be treated a certain way because I felt I had to for my career."
But the 'Passengers' actress believes "every human" should be treated with "respect" they deserve and shouldn't be forced to do things to please other people.
She explained: "I'm still learning that I don't have to smile when a man makes me uncomfortable. Every human being should have the power to be treated with respect because they're human."
And Jennifer has admitted she now has an "understanding" of the entertainment industry, but she used to find her celebrity status "overwhelming".
Speaking previously, the 'The Hunger Games' star said: "Now I have an understanding, I have a patience with it. Also I get time off from it, I think at first it was really overwhelming and I was like 'Is this what it will be like for the rest of my life?'.
"But when I am releasing [a movie] it is really heavy and really intense, and I know it will die down and people will stop caring pretty quickly."
And Jennifer has admitted she will always be honest and open up about her feelings because she is not fazed by the consequences or backlash she may receive from the comments she makes.
She said: "I don't really have a choice, which can be scary sometimes. Because if it was something I was doing on purpose then when I get bit by it I can be like 'Oh I'm not going to do that anymore'. But I don't really have the ability to be different. So when it bites me in the ass it bites me in the ass.
When I do say something and I want to put my foot my mouth I move on. Otherwise I'd be in a foam room."