How do we burn fat?

Henry S. Lodge, MD
Internal Medicine
Most fat isn’t stored in your muscles; it’s stored around your belly and hips and in a few other prime locations. Your body has to bring it to your muscles through your circulation. That’s harder than it seems, because your blood is largely water and fat doesn’t dissolve in water. Fat has to be carried in special molecules called triglycerides, which your doctor probably mentioned during your last checkup. The trouble with this, from your muscles’ perspective, is that your capillaries can handle only a few triglyceride molecules at a time. So each capillary can deliver only a trickle of fat to your mitochondria. With consistent aerobic training, your body builds vast new networks of capillaries to bring more fat to your muscles.
Younger Next Year for Women: Live Strong, Fit, and Sexy - Until You're 80 and Beyond

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Younger Next Year for Women: Live Strong, Fit, and Sexy - Until You're 80 and Beyond

Co-written by one of the country's most prominent internists, Dr. Henry "Harry" Lodge, and his star patient, the 73-year-old Chris Crowley, Younger Next Year for Women is a book of hope, a guide to...

Burning off fat is requiring us to burn more than we consume. Take 1 pound of fat. You would have to burn 3500 calories to lose that one pound. So if you look at it this way if you eat 1500 calories per day and burn 2000 calories per day you would be in a deficit of 500 calories per day. In turn you would lose 1 pound of fat per week. The bigger your deficit is the more weight and body fat you will lose. On the other side building muscle will also help us burn more calories as well. For ever pound of muscle gained you will burn 30-50 extra calories. Gain 10 pounds of muscles and your body can be burning up to an extra 500 calories per day. So many factors can go into how you can burn the body fat off.

When we burn fat we are simply using up a stored supply of energy. Since energy is never lost it only changes forms when you eat more than your body requires you store the energy as fat. If your body is gaining fat than you can be reasonably sure you are eating more than your body needs. We burn fat when we consume less calories than our body demands on a daily basis. This is why we can be sure that everyone that needs to, can lose body fat. All diets (while not all good for you) can cause a weight (fat) loss when they put your body into deficit. Deficit means when you take in less calories then you need. I can honestly say, while not endorsing and qualifying by saying that this would be very unhealthy, a candy bar diet could cause weight loss. Please don't misunderstand I am not saying that anyone should do that I am just saying that if you take in less calories than you need on a daily basis you will burn stored energy and lose weight.
Under the Law of Conservation of Mass, matter is not created or destroyed, but may change its form through chemical reaction. So, when we lose mass in our bodies by burning fat, it doesn't simply disappear -- it changes form, like water and steam.

When we consume food, the sugar and glucose harnessed from carbohydrates are our first fuel sources. Glucose is stored in our liver in the form of glycogen. The liver releases it into our bloodstream as necessary to keep our body going. Picture your bloodstream as a conveyor belt - taking nutrients to body parts that need them. After that glucose runs out, fat takes over. Burning fat to harness energy is called ketosis.

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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.