When you're trying to lose weight and build muscle, the question is often, "Which one should I do first: lose weight or build muscle?" This question is looking at the problem from the wrong angle. It assumes that you have to complete one before starting the other. In reality, you can work on both problems (excessive body fat and a low amount of muscle mass) at the same time.
Most people think they should only do cardio when trying to lose weight. Cardio burns a lot of calories and is therefore the best exercise to help get rid of unwanted body fat. While it's true that cardio will help you lose weight, a good strength training routine will help you look better and be healthier.
Incorporating some strength training, either before or after your cardio, will help you burn more calories in two ways. First, you're exercising more which burns energy. Second, when you increase the amount of muscle on your body, your metabolism will speed up.
Unlike fat tissue, muscle burns energy even when you're not exercising. This will increase the amount of calories you burn on a daily basis and help you lose weight faster.