What It Means to Burn Fat by RunningThe body primarily uses carbs and fat as energy to fuel runs. The ratio of carbs and fat changes depending on your speed and intensity. For high-intensity running, such as interval workouts, the body will rely more on carbs for fuel than fat because they're a quicker source of energy. For long, slower runs, your body starts using fat as an energy source.
What It Takes to Lose Fat by RunningSo, you would think that to lose fat, you should just do a lot of slow running, right? That's not the case. When you're trying to shed pounds, it doesn't matter what type of fuel you use. Just because you're using more fat as energy doesn't mean you're losing fat or burning more calories. In order to lose weight, you need to burn more calories than you're taking in, simple as that. With running, as with other forms of exercise, the harder you work, the more calories you'll burn.
How to Burn More Calories RunningTo burn more calories when running, you can run at a higher intensity. High-intensity running is running at about 80-90% of your maximum heart rate. You're not doing an all-out sprint, but you definitely shouldn't be able to carry on a conversation.
While you'll burn more calories during high-intensity runs, it's important that you don't do all your runs at a high intensity. Some of your runs should be easy runs so that you protect yourself from overuse injuries and give your body a chance to recover and rebuild itself to get stronger. It's also good to vary the intensity of your runs so that you don't get burned out or bored with your routine.
If you've been running several days a week for at least a few months and you've built up a good running base, it’s safe to introduce one or two high-intensity runs into your weekly workout. You can try doing a 20-minute run (after warming-up properly) at about 80-90% effort. Or, do an interval workout, where you alternate between running at a fast pace for short intervals, such as 1-2 minutes, then recovering at an easy pace for 1-2 minutes. Try doing 10 hard and easy intervals. As you become more fit, you can increase the time of your intervals or do more repetitions.
Also see: Can I Lose Belly Fat by Running?