Model Bella Hadid is desperate to get her curves back after "accidentally" losing weight by working out and sticking to a strict diet.

The runway beauty will make her Victoria's Secret Fashion Show debut in Paris, France next month (Dec16), and while she is actively working to tone up her body, she insists criticism about her slender frame is unwarranted because she isn't trying to slim down.

"I have lost weight and gained weight," she tells People.com. "My weight fluctuates so much. I really didn't mean to (lose weight). Like, I want boobs. I want my a** back. But it's not my fault.

"My weight fluctuates and so does everybody's and I think that if people are gonna judge, that's the worst you can possibly do because everybody is different."

Bella blames her incredibly healthy eating habits for her shrinking size, but she is happy with the way she looks.

"I worked out so hard and everybody is like, 'Oh, she looks so skinny blah, blah, blah,'" she continues. "But I think that if you just stick to something you can really achieve so much. I've been eating hard protein every day, and working out for three hours every day. It's crazy but I think that, you know, if you set your mind to something I think you can succeed."

And Bella, 20, reveals she rarely strays from her lifestyle routine, even though she travels so much for modeling gigs.

"I like to eat healthy and not eat crazy plane food," she shares. "I like to still make sure my diet is good and I stay hydrated and stuff. That's basically all I do."

Bella will have some family support backstage at the Victoria's Secret Fashion Show on 5 December (16) - older sister Gigi Hadid is also set to strut her stuff in lingerie, returning for a second year after her 2015 brand debut.