Irina Shayk is losing the baby weight so quickly! Bradley Cooper's fiancée looked gorgeous outside her pilates class on Monday. Shayk was spotted after her private session in Santa Monica, Calif. She rocked an all-black workout outfit along with furry flip flops.

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It's hard to believe Shayk had a baby a few weeks ago. She and Cooper welcomed daughter Lea de Seine in late March.

But this isn't the first time Shayk has showcased her post-baby body. Last month, she posted a stunning bikini photo on Instagram. She captioned the pic, "Pre-sunset #currentsituation."

Irina Shayk Irina Shayk lost the baby weight quickly thanks in part to her fast metabolism (Photo: BENS / BACKGRID).

"When Irina had her baby she lost most of the unwanted weight right away," a source told E! News. "She has great genetics."

The insider added that Shayk took about a week off after having the baby. But after that, she "went hard" with her workouts. And her fiancé has been fully supportive.

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"She has done a mix of cardio, weights and eating really clean," the source said. "She has been working with Bradley Cooper's trainer as well as a few other fitness gurus that been helping her. Bradley and Irina have many things in common and fitness is one thing. They both work out together and take care of themselves. She has jobs that are coming up that she is contracted for soon, so getting back in tip-top shape is a priority."

Of course, Shayk stayed in shape throughout her pregnancy, which made it easier for her to lose weight after giving birth. Sources told E! News in December that she was still "exercising in moderation." That helped her burn calories even though she gave in to some of her food cravings.

Irina Shayk and Bradley Cooper Irina Shayk and Bradley Cooper have been working out together since she had the baby (Photo: BACKGRID).

Shayk has actually said that she doesn't have a special secret for her amazing body. "You just have to live a healthy lifestyle," she told Bally.com earlier this year. "I get 8 hours of sleep which is a must as I love sleep. Drink plenty of water wear sunscreen and eat healthy... most of the time."

Indeed, Shayk told Women's Health that she will occasionally splurge on burgers and cake. But she will make sure to work out the next day and eat a healthier meal like fish and vegetables. The E! source added that since having the baby, Shayk is "staying away from fatty foods," except for "cheat days."

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Shayk also has a series of go-to workouts. She started jiu-jitsu last year with her personal trainer. And when she's in a hotel, she does barre exercises that don't require a lot of space or equipment. "I’m in hotel rooms most of the time, and it can be hard to find a hotel with a nice gym," Shayk told Vogue in December. "It was important for me to have a workout I could do in my room."

What do you think of Irina Shayk's weight loss? Let us know your take in the comments section below!