Aerobic exercise such as walking, riding a stationary bike, or running is a good way to accelerate the fat burning process, as long as it is not overdone and as long as it is used only in addition to a good weight training program. It should never be used as a substitute for weight training since it does not permanently increases your metabolism and since it does not has the ability to re-shape your body.
Fat Burning Zone
In order for aerobic exercise to be effective, it needs to be performed within the fat burning zone. The fat burning zone is the zone at which you are doing enough work to burn fat. Your pulse (how fast your heart is beating per minute) determines this zone.
The fat burning zone formula is the following: