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Jessica Biel


Jessica Biel debuted an amazing post-baby body back in May, more than a month after giving birth to her and husband Justin Timberlake's first child, son Silas Randall Timberlake.

And she also looked fantastic while heading to the gym last week (see above).

So how did she do it? The 7th Heaven alum's longtime personal trainer, Jason Walsh, told E! News exclusively on Friday that he has been working with the actress about two to three times a week.

Walsh made his comments at the opening of his new fitness studio, Rise Nation, in West Hollywood, California During a 30-minute class there, a person could burn between 500 and 800 calories.

"This is a great for post-baby...Rise Nation is fantastic," he told E! News. "Mothers, after having the kid, they really need to pay attention to the breastfeeding and stuff like that. She can't really lose everything 'cause she is breastfeeding. It's going to take a while. At least here, we aren't doing too much. She can kind of go at her own pace and it's fantastic."

PHOTOS: Jessica Biel debuts her amazing post-baby body—see the first pics!

Walsh's clients typically use body climbing exercise machines called VersaClimbers.

"Anyone can do it," Walsh told E! News. "The great thing about the VersaClimber is its super safe. It's a natural motion; it's a crawling motion. We're all born with it. It's low-impact. It reinforces proper movement patters. It's the upper and lower body. I'ts huge cardio or conditioning impact. Metabolically speaking, it incinerates calories more than anything else out there."

Prior to her pregnancy, Biel worked out with Walsh up to four times a week.

"I don't want to stress her out too much," he said. "We can do enough to progress and get back into it."

Jessica Biel


Jason Walsh, Hilary Duff

Mark Davis/Getty Images for Rise Nation

Other celebrity clients of Walsh include Hilary Duff, mother of 3-year-old son LucaMinka Kelly and Matt Damon, who also attended the studio opening.

"Matt is absolutely the best client anybody could ever hope for," Walsh told E! News. "He is hard-working and he is funny as hell. So we keep it light, but we work really, really hard. He sees and feels the benefits of training the way we train. My philosophy for training the movement has helped him get past back pain, shoulder pain."

Jason Walsh, Matt Damon, Luciana Barroso

Mark Davis/Getty Images for Rise Nation

At the event, Damon was accompanied by his wife, Luciana Barroso, with whom he shares four daughters.

"You want to live longer and health because you have these kids and you want to play with them and go to Disneyland and you want to do these things without pain," Walsh said. "And that is the focus we took with him."

John Krasinski, Jason Walsh, Emily Blunt

Mark Davis/Getty Images for Rise Nation

Jason Walsh, Ashley Tisdale

Mark Davis/Getty Images for Rise Nation

Other attendees included Ashley TisdaleJohn Krasinski and wife Emily Blunt and Lily Collins

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