Get Lean and Sculpted in 4 Weeks Flat! Part 2: Cardio

Recipe for Success

We've found the perfect body-shaping formula that's guaranteed to get results! It's called undulating periodization -- but don't let the techy-sounding name scare you. This is actually a simple way to sculpt muscle, blast fat, combat cellulite, and keep you challenged by systematically varying your strength and cardio workouts each day. And we've got the science to prove it: Studies have found that women who followed similar resistance and aerobic training workouts lost up to 23 pounds of fat in six months while increasing strength, power, and lean muscle mass. Follow our total-body strength training and corresponding cardio program while also following a healthy diet and you'll see sleeker muscles and less body fat in just four weeks. Now that's what we call a recipe for success!

For the first part of this workout, Part 1: Strength, check out our easy step-by-step slide show, with photos to show you how to execute each move perfectly.

One of the best ways to maximize fat loss and get more out of your aerobic training is to vary both the duration and intensity of your cardio workouts. To improve your body's ability to burn calories efficiently, incorporate the following three routines into your weekly plan. You can do these workouts outdoors, either running, cycling, or walking, or on any cardio machine, such as a treadmill, stationary bike, stair climber, or elliptical. Cross-train with different modalities to prevent burn-out and improve results. As you get fitter, the routines will get both slightly longer and harder. For each workout, follow your rate of perceived exertion (RPE), or how hard the exercise feels on a scale of 1 to 10 with 1 being very easy and 10 being very difficult.

Work at a steady intensity that's comfortable but challenging throughout.