You can do this simple exercise by lying down on your left side with your elbow directly beneath your shoulder and your legs one on top of the other. Place your right hand on your right hip. Now, tighten your abs and lift your hips off the floor. This way, you will be directly working the abdominal muscles. Hold for a minimum of 30 seconds and repeat on the other side.
If you want to build muscle and burn fat at the same time, you have to perform circuit training three days per week. How can you achieve this? Indulge in full body exercises like lunges, push-ups, and pull-ups, for one set of 15 repetitions. Don't forget to follow every exercise with one minute of jumping rope. You should be able to burn around 500 to 600 calories per workout.