At least, that's what Star magazine hears. Via The Sun:
[Johansson] has reportedly lost over 14lbs since she began working out with her Iron Man 2 co-star in preparation for the movie.
A source told Star magazine: "The pair have been doing daily workouts with Gwyneth's personal trainer TRACY ANDERSON."
Maybe Johansson can complain further about the extreme weight loss plan (as she did a couple of weeks ago in London) on Paltrow's website Goop, cementing its position as the definitive online shop of body-image horrors.