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Even Gwyneth Paltrow struggles with a few extra pounds.

"She has her moments where she goes up a little, but we get her right back down," Tracy Anderson told of the actress' weight at the Institute for Civic Leadership benefit at Diane von Furstenberg's NYC studio Wednesday.

"She just gained all that weight for her movie, and we just took that all off," continues Anderson, referring to drama Love Don't Let Me Down, shot in Nashville, from where Paltrow blogged about chowing down on ice cream sundaes and fried chicken. ("She pigged out!" Anderson told Us earlier.)

To get slim again, Paltrow, 37, worked out for an hour-and-half a day with a combination of trainer Tracy Anderson's dance cardio and a specially-made "terrifically difficult leg series" video, Paltrow wrote in her GOOP newsletter.

She followed Anderson's strict diet -- which includes kale juice and super low-carb vegan wraps -- for five days.

Anderson also tells Us her pal is "coming out with a cookbook," due this fall. My Father's Daughter, Paltrow has explained, will focus on cooking for the entire family.