Another way to phrase this question is “What kind of stored fuel will my body burn when I exercise?”
I like this way of putting it, this allows me to give you a bit more information about how the body works.
When we exercise our body uses a combination of three types of fuel (energy): Carbohydrates, fat and protein, (interesting to note that those are the same three macro nutrients we eat).
The type, the duration and the intensity of the exercise will cause the body to draw from the different stored fuel sources. In addition, something that is often overlooked is how the body reacts to exercise afterwards which then affects our metabolism.
These four “things” plus target heart rate have a great affect on which fuel source gets used for exercise.
Aerobic (with oxygen): exercises which are generally performed at a slower pace and with less effort. The good news is it usually burns a greater degree of the fat. Fat is a slow-burning stored fuel which requires oxygen and exercising at lower effort enables the cells to use this energy more efficiently, meaning a greater percentage of fat can be burned when exercising aerobically. The bad news is aerobic exercise is an effective way to lose fat weight only if you are motivated enough to workout frequently for longer durations; (it only burns fats while exercising). So you need to be able to exercise daily and for longer periods, at least an hour.
Anaerobic exercise causes the energy system to shift towards burning mostly carbohydrates (carbs) because the exercise requires moving at an increased pace or with a greater effort and the demand for oxygen cannot be delivered in sufficient quantities to allow cells to continue burning fat. The good news is exercising this way burns more calories and increases metabolism over the following 12 to 24 hours. The best way to loose body fat is to raise your metabolism.
The bad news is its harder to work out this way, it takes a higher fitness level and recovery time can be longer and this could mean fewer workouts per week.
So what’s the answer to the question “how should I exercise to burn fat”?
The first hurdle that you will need to overcome is commitment. If you want to loose fat weight and change your body composition, then you have to make a commitment. If you are a beginner then I suggest starting with aerobic exercise that has longer durations; this will also increase your fitness level. Make it fun so you enjoy it, then you will have a better chance of sticking to it. Next start adding in some other exercises that include the whole body, like weight training or swimming and increase your intensity.
Remember the body does burn a higher percentage of calories from fat in the 'fat burning zone' or at lower intensities. But, at higher intensities, you burn a greater number of overall calories.