How Much Fat Can I Burn by Running?

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While running is a great way to lose weight, it is important to understand the difference between burning fat and burning calories. Fat and calories are not the same things.

Fats are the greasy substances found in our bodies which can accumulate the more we eat. A calorie, by contrast, describes how much energy is needed to fully metabolize a food whether it be a fat, a protein, or a carbohydrate.

When you first start your workout, your body primarily uses carbohydrates for fuel. This is because carbs are far easier to burn than fat. While this can help trigger weight loss, it doesn't necessarily burn fat. To do so, your body needs oxygen.

To this end, you need to exercise to the point where your heart is pumping at or near its target rate. It is at this stage that your body will start burning fats more readily than carbs.

Comparing Fats and Carbs

When you exercise, the ratio of carbs and fat your body uses for fuel can change depending on the speed, duration, and intensity of the workout. Think of it in this way:

  • For high-intensity running, the body relies more on carbs simply because they're a quicker source of energy. They provide your body with the burst of energy it needs when launching something like a sprint. It's like putting a match to paper: it burns hotter and faster but then is quickly over.
  • For longer, lower-intensity runs, your body gradually shifts from carbs to fat. While fats may not be as immediate a fuel source, they are more sustainable. In this sense, burning fat is more like lighting a candle: it burns steadier and longer.

You can also burn fat more readily if you are in a fasted state simply because there are fewer carbs in your system. This doesn't mean that you should work out on an empty stomach. Instead, start your morning with a 100- to 200-calorie snack packed with protein and carbs. This will give you ample fuel for a workout and may even act an appetite suppressant once you're finished.

Burning Fat vs. Weight Loss

If your goal is to burn fat, it would seem reasonable to work out at a slower but steady pace, right? Not necessarily. While exercising at a lower intensity will allow you to burn a greater proportion of calories from fat, working out at a higher intensity means that you're burning more calories overall.

And this is where people often get confused. Remember that calories are a value—a unit of energy assigned to any food we eat, including fat. If you're trying to shed pounds, it doesn't matter which type of fuel you use. Just because you're burning more fat doesn't mean that you're burning more calories. Calories are what you need to focus on.

In the end, burning fat doesn't mean a thing if you take in more calories than you metabolize. To lose weight, you need to burn more than you consume; it's as simple as that. With running, the harder and longer you work out, the more calories you will burn. Burn enough calories and the fat will follow.

How to Burn More Calories Running

To burn more calories when running, you would need to run at a higher intensity pace, roughly 80 percent or 90 percent of your maximum heart rate. At this speed, you're not doing an all-out sprint, but you're working hard enough so that you're not able to carry on a conversation.

It's important, however, that you not run at this pace all of the time. After strenuous activity of any sort, you need to give your body a chance to recover and rebuild itself. After running for several months and building a solid foundation, you can gradually begin to introduce one or two high-intensity runs per week.

Start by doing a 20-minute run at around 80 percent to 90 percent intensity. Alternately, you can do interval training where you alternate between high- and low-intensity workouts. As you progress and become more fit, you can extend the time of the intervals as well as the repetitions.

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