How does exercise burn fat?

Your body needs fuel in order to function and perform work (such as exercise). Your body gets this fuel from the foods you eat. Foods can be divided into three macronutrients; carbohydrates, fat, and protein. Your body’s primary source of energy comes from carbohydrates. Carbohydrates such as fruits, vegetables, and whole grains are extremely important to give you the energy you need to exercise and perform activities of daily living. The body’s next source of energy is fat. Like carbohydrates, fat can be easily converted into fuel the body needs. And sometimes protein can be used as fuel; but its primary function is to build and repair tissues.

When you exercise your body will primarily “burn” carbohydrates and fat; much like a car uses gasoline. Exercise helps someone burn fat because exercise requires more fuel than being sedentary (like a speeding race car needs more gasoline). As you exercise your body will convert fat to be used as fuel for working muscles. In addition, as someone becomes fit their body becomes more efficient at using fat as a fuel source.

During exercise the body needs extra energy, which it gets from burning fat. Fat is released into the bloodstream, where it travels to the muscles to give them the energy they need. This makes the muscles work better and helps shrink fat cells, so people keep a healthy weight.

Pam Grout
Alternative & Complementary Medicine Specialist

One of the main reasons exercise burns fat is because it increases the rate of oxygen that's delivered to your cells. When you run, for example, you increase your oxygen intake from seven or eight liters per minute to thirty-four or more liters per minute. Consequently, your body has oxygen to attend to all its energy needs. If your body has accumulated excess fat, that means your body doesn't have the oxygen or the energy it needs to process the food you're taking in.

Jumpstart Your Metabolism: How To Lose Weight By Changing The Way You Breathe

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Jumpstart Your Metabolism: How To Lose Weight By Changing The Way You Breathe

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Fat stores energy that your body can use. When you exercise, your body uses more energy, so fat burning can occur. However, there is a balance of energy in and energy out. If you eat more calories, which cause you to store fat, you need to increase your exercise in order to burn the store of fat that you made.

Jonathan Penney
Fitness Specialist

Exercise will burn calories.  Every 3,500 calories is 1 pound of fat. By exercising you are increasing your heart rate, increasing your heart rate will require your body to work to keep itself cool which will result in calories burned. 

Most everyone has some excess fat that they can burn. Exercising correctly by incorporating strength and cardiovascular training then you will be successful in burning fat and losing weight. Be sure to complete more than just cardiovascular exercise to keep strong muscles and bones.

Exercise burns fat very simply. The more calories you burn compared to eating the more weight and body fat you will lose. In basic math, if you burn 3500 calories you will lose 1 pound of fat. So, if you can keep your deficit at 500 calories a day you will lose that 1 pound of fat per week.

Joanne Duncan-Carnesciali, CPT, NASM Elite Trainer
Physical Medicine & Rehabilitation Specialist

One of the biggest misunderstandings in the world of fitness is the fat burning myth.

It is so important for you to view fat simply as fuel  that the body uses to create energy so that we can move about. Even more interesting, is the fact that the body uses carbohydrates which is stored in the body as glycogen as fuel in order to create energy so that we can move about.

Think about it like this:  there are some cars that use electricity as fuel to propel itself, some that use leaded, super unleaded, or premium gasoline, some that use diesel, however the outcome is the same. The car moves.

You might ask what does this have to do with fat?

Well, fat and carbohydrates are the primary fuel sources the body uses to create the energy that we need in order to move. That energy is called ATP. 

Whether the body uses fat or carbohydrates as a fuel source in order to produce this ATP is dependent upon how intense one is working.

Here's the part that gets most folks disappointed.....

The body uses fat as fuel exclusively when we are in deep sleep. That's a good thing because we have sufficient stores of fat to create the ATP we need throughout the night to keep our organs functioning. Thank goodness!

However, when we engage in work of greater intensity we use a mixture of both fuel sources carbohydrates and fatThe more intense we work out, the body uses a higher percentage of carbohydrates than fats a fuel source.

This doesn't mean that you are not burning calories and working toward your goal of weight loss. All it means is that while you are working out and getting stronger your body is utilizing the perfect fuel source your body requires at that moment to produce ATP so that you are successful in reaching your fitness and wellness goals.

The only real way to lose body fat is by burning more calories than you consume. You can accomplish this by eating less, moving more, or a combination of the two. Exercise burns fat because it can help you create a calorie deficit in a couple of ways. First, if you add resistance training (weights, resistance bands or even body weight movements) to your routine, then you will build lean muscle mass. Extra muscle will make you burn more calories throughout the day—even at rest! Cardiovascular exercise (walking, running, swimming, etc) will raise your heart rate and have a positive effect on your metabolism too. This will also enable you to burn more calories and, depending on the intensity of your workout, can even increase metabolism hours after your workout is complete.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.