Credit: David Livingston/Getty

Tia Mowry is kicking off summer with a slimmer physique.

The Sister, Sister alum flashed her abs on Instagram Wednesday in a full-length mirror selfie as she let her followers in on the weight she dropped and how she did it. "I've lost 20 pounds! Many asked how? Diet and cooking out of my cook book #wholenewyou," she captioned the snap.

In it, she stands in front of a mirror in workout leggings, a white baseball cap, and flip flops as she pulls up her white top to proudly show off her toned abs.

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The 38-year-old actress's cookbook, Whole New You: How Real Food Transforms Your Life for a Healthier, More Gorgeous You, teaches readers how to replace the processed, packaged food in their diets with whole foods like fruits and vegetables.

Still, Mowry enjoys the occasional treat every now and then. Just hours before her reveal, she shared a photo of herself enjoying an ice cream cone in workout clothes. "Ice cream didn't stand a chance," she wrote alongside the snap.