Any type of aerobic exercise, which is one in which you are exercising at a constant pace for a long duration, will help you burn fat. You only need to get to a moderate intensity to start burning fat. However, performing aerobic exercises for the same amount of time at a higher intensity will burn even more calories and help your metabolism stay active for longer after your workout. Try a variety of aerobic exercises to burn the most fat.
Swimming engages the whole body and gets all of your muscles working, which burns more calories and fat. If you are not a very good swimmer yet, start by resting up to 30 seconds between each length of the pool. Another option is to use a kickboard and focus on exercising your legs, which does not burn as much fat but gives you the assurance that you will stay afloat.
An elliptical machine provides a low-impact alternative to running and can also be easier for people with lower fitness levels to master because the machine helps you keep taking strides of the same length, even when you get tired. Aim for 30 to 60 minutes of moderate-intensity exercise to burn fat. You should be able to carry on a conversation when you are exercising at the correct intensity.
If you don't have any exercise equipment, you can still walk or run and burn fat that way. If you are just starting out with aerobic exercise, take walks first and focus on taking large, quick strides to get your heart rate up and build muscle. As you are able, transition into alternating intervals of jogging and walking to burn more calories.
Bicycling only works your lower body, but it is still an effective aerobic exercise for burning fat. Use a recumbent cycling machine with a back rest if you have trouble balancing on a regular bicycle. If you have a real bicycle and the weather is good, cycle outdoors to get fresh air and motivate yourself to keep going to finish your loop and get back home.