The 39-year-old actress wore the Stella McCartney gown to The Costume Institute Gala earlier this week, but it was so heavy when she first tried it on, she had parts of it cut out, reported Contactmusic.
"It was just strips and strips of rhinestones. Stella sends me this email on Friday, like 'Babe, your dress might be a little heavy.
"I put it on for the last alteration and it is 30 pounds. We managed to cut eight pounds out of that dress. My knees are so sore today!" she said.
Like Diaz, 'Vampire Diaries' actress Nina Dobrev too had trouble with her dress. The 23-year-old actress had to be cut out of her Donna Karan atelier gown every time she wanted to visit the bathroom and then sewn back in afterwards.
"It was so form fitted and made of vintage gold metal, and so tight. It was beautiful. They literally had to sew me into it so everything fit and then they sent me off," Dobrev said.
"You call the designer and they have an emergency sewing kit, they cut you out of it, and then they will sew you back in," she added.