Rebel Wilson had to fight back tears as she opened up about her 28kg weight loss.
The Australian actress (40) said in an Instagram video she had failed to treat her body with "love and respect" in the past.
The Pitch Perfect star - who earlier this year set herself a target of reaching a weight of 75kg - said she was developing "self love".
"I wasn't valuing myself and telling myself negative things. That was hard," she told her followers.
"I'm trying to change those patterns, so you're more loving and treating yourself with respect.
"I'm working on self love, and that's a hard concept to master."
In the video, Wilson said she was motivated to improve her diet by the desire to freeze her eggs in case she wanted to start a family in the future.
"I was thinking about fertility and having good quality eggs in the bank, so I was like, 'OK, I'm going to do this. I'm going to get healthy'.
"I did go to a professional place to do a detox," she said.
The actress credited Austria's VivaMayr wellness centre with leading her to change her diet and start exercising more.
"I wrote a little letter to myself about how I'm really gonna give it my all this year, and then I did."
Wilson also revealed she has been consuming under 1,500 calories a day while exercising "like a beast".
"Nutritionally, the only thing is I do try to stay under 1,500 calories because of my body type. If want to lose weight in that week, I kind of have to stay under the 1,500 each day."