Director Darren Aronofsky recently admitted he became so worried about Portman's weight loss, he begged the skinny actress to eat.
And now Kunis has revealed her own shrinking figure alarmed her relatives.
She tells E Online, "My mom freaked out. Everybody started panicking. She was like, 'You have to promise me this isn't going to affect you.' I was like, 'I promise it won't, but it might take me a little time to be OK with having a little more fat on me.'"
The 27 year old admits that although her skinny frame looked good on film, she hated her shapeless figure and happily piled the weight back on once the film wrapped.
She adds, "I could see why this industry is so (messed) up, because at 95 pounds, I would literally look at myself in the mirror and I was like, 'Oh my God! I had no shape... All you saw was bone. I was like, 'This looks gross'. But in photographs and on film, it looked amazing...
"It took me five months to lose 20 pounds, but it took me just five days - days! - to gain it all back."