The model and actress, 35, was snapped looking very happy outside Barry's Bootcamp in LA on Tuesday (10 March). We're guessing it was a good workout, then!
Barry's is popular with a string of stars including Kim Kardashian West, and boasts some of its workouts can burn up to 1,000 calories per hour.
Kelly was unveiled as the latest brand ambassador for the Atkins Diet earlier this year, saying she had noticed changes in her body while filming new US TV show One Big Happy as she kept reaching for sweet treats on set.
She has, however, insisted: "I'm proud of my curves and they aren't going anywhere."
Kelly's new sitcom premieres on US screens next week.
She stars as a British woman who falls in love with an American man, played by Nick Zano. It's a bit complicated though as he's agreed to have a baby with his lesbian best friend, played by 24's Elisha Cuthbert.
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