In order to burn fat, your body has to be working at a certain rate and time frame. There can be a misconception that the longer you are in the gym the more fat you will burn. This is not true at all. If you are in the gym for hours trying to work hard, sure you will burn calories but you will also be burning muscle not just fat. In order to focus on burning fat in a shorter time frame, there are three things you need to focus on. Number one is your rest periods. Generally thirty seconds to one minute is a good rest period in-between sets for weight loss and even getting your endurance up.
Shorter rest periods means you can will keep your heat rate up but not too much, be able to do more exercises in a shorter time frame and help burn fat and build muscle quickly. Number two is to focus on full body movements. For example: Performing a ball squat to press. You are using multiple muscles in that movement, meaning you will burn more calories. You still want to focus on separate muscles such as a lat pull down for your back but also adding full body movements in your routine. Number three can be something people love or hate but doing cardio. In order to burn more fat doing cardio, focus on doing it after weight training for about thirty minutes. Your body will get to a point where it will start to break into your fat storage more than your energy storage. This can be about thirty to 45 min into weight training. Do more in a shorter time weight training and then move right into cardio. You will see a lot better results faster and safer.