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"Weight loss/maintenance basically comes down to calories-in vs. calories-out: if you take in fewer calories than you expend, you'll lose weight," Schoenfeld says. "So you can't expect to simply eat as much as you want and then exercise away the excess. Fitness is only effective as a weight-loss aid when you control the amount of food you consume."

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While cardio plays an integral role in accomplishing a better body, the true strength in your workout lies in weight training. Lifting weights not only builds muscle, but also promotes fat loss. Adding muscle raises the metabolic rate, Schoenfeld adds.

"If you train metabolically, it helps to further increase the amount of calories that you burn 'after' the exercise session for up to 72 hours," he explains. "Adding in some cardio can definitely help with fat loss, too, so the combination is beneficial."