Celebrity Fans: Kim Kardashian, Katie Holmes, Jessica Biel, Sandra Bullock, Carrie Underwood, Amanda Seyfried, Christina Applegate, Katie Couric
With an estimated 1,000 calories burned per one-hour class, it's easy to see why so many A-listers are flocking to get their bootcamp on with Barry. Voted "The Best Celebrity Workout" in multiple publications, the high-energy, action-packed class with a killer playlist actually makes interval training fun. Each session alternates between guided treadmill runs and resistance training with elastic bands, body bars, and kettlebells. Every class is different, and you won't be able to move after any of them—but hey, isn't that a good thing? Pricing starts around $15 to $24 per class, depending on the package.