Stress is the secret behind her slim frame, says actress Sarah Jessica Parker.
The Sex and the City star made the revelation at the London premiere of Did You Hear About The Morgans?, reports the Telegraph.
When quizzed what kept her in shape, the star replied: "By running around, stressed, no sleep. I guess I try to be disciplined."
The mum-of-two co-stars with actor Hugh Grant in the film about a couple who join the witness protection programme.