New Delhi, Feb 20 : `The O. C.' star Mischa Barton has revealed that Pilates is the secret behind her slim frame.

She said: "For me, it''s all about Pilates recently. I''m obsessed with Pilates. I think it''s so fun."

The 23-year-old actress had recently sparked concerns for her health after displaying an increasingly thin physique, reports the China Daily.

Mischa hit out at critics of her weight loss, insisting she has never embarked on faddy diets or extreme exercise regimes.

She added to America''s OK! magazine: "I don''t do any crash diets. There''s nothing that I really do like that, because I''m always working. I mean, before I go do a film, I do workout more. I do get ready for a film and try to be healthy and in shape. And when I''m not working, I do less of it.

"I do more cardio because I work long hours. Jogging, running - stuff like that''s really good before you do a film so you have more energy." (ANI)