Many runners who are trying to lose weight by running wonder if there's a certain pace or distance they need to hit to start burning fat.
Although running is a great way to lose weight and inches, it's important to understand the difference between "burning fat" and "losing fat," as well as what it takes to lose weight.
The body primarily uses carbs and fat for fuel during 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 taps into fat for energy.
So, 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. With running, as with other forms of exercise, the harder you work, the more calories you'll burn.
To 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. (Rest days are important, too.) 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, it's safe to introduce one or two high-intensity runs into your weekly workout. You can try doing an interval workout, where you alternate between running at a fast pace (about 80-90% effort) 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.