What Happens To Lost body Fat?

by Randell Allen on December 18, 2010

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98% of the energy stored in your body comes from fat.  This translates into approximately 50,000 to 200,000 worth of calories of potential energy.

Fat acts as a potential food source in times of food deprivation. We have plenty stored to keep us alive for weeks to months with little to no food.

You may be surprised to hear that you are always burning body fat. Even at rest your muscles are burning over 60% of your calories (carbohydrate is another major fuel source) from fat. So, you are burning body fat even when you are sitting and watching television, or working on the computer at Starbuck’s.

However, you are always storing body fat too. At the end of the day, you have usually used the same amount of fat for energy as you have stored, so your weight stays the same.

During moderate exercise (biking, power walking, jogging etc...) the hormone adrenaline stimulates an increase of fatty acids released into your blood to be transported to your working muscles to be used for energy. That's right, your muscles are what burns fat. The longer the exercise session, your body begins to utilize more fat for energy and less carbohydrate.

This is the reason a longer bout of exercise for 30-60 minutes is recommended for weight-fat loss.

This is also the reason for training your body to preserve muscle mass. The more muscle you have, the more fat you will potentially burn.

Exercise is the only means to begin burning more fat than you are storing. There is a direct correlation between muscle mass and calories/fat burned. The type and amount of food you choose, and the type and frequency of exercise you choose has a huge impact on your fat burning capabilities. Please visit personal trainer Los Angeles, for more information…

Now, here is where it gets a bit scientific. There is a process called beta-oxidation where your muscles (or liver) further break down fatty acids for energy. The end result of beta-oxidation breakdown of fatty acids is carbon dioxide and water.

Other fatty acids may be converted into ketones and secreted through your urine. ketones may also be used or energy by muscles and the brain. Ketones production is highly dependent on food choice and food amounts. Certain low calorie or high protein diets will increase ketone production.

The remaining fatty acids are stored again in the adipose tissue (fat tissue) in a process known as re-esterification.

What happens to lost body fat?

1. Fatty acids are burned in your muscle and broken down to carbon dioxide and water

2. Fat acids get converted to ketones by your liver or muscles and used for energy or secreted in the urine

3. Fatty acids get mobilized into the blood and restored again as fat (re-esterification)

Randell Allen is a nutritionist/personal trainer and the creator of NutritionX. If you are looking for help with your weight loss goals, please visit weight loss Los Angeles for more information.



Jeukendrup AE. Modulation of carbohydrate and fat utilization by diet, exercise and environment. Biochem Soc Trans, 2003 Dec;31(Pt 6):1270-3.

Food and nutrition board, institute of medicine of the national academies (2005).Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, FattyAcids, Cholesterol, Protein, and Amino Acids (Macronutrients). National Academies Press.

Shetty PS (1990): Physiological mechanisms in the adaptive response of metabolic rates to energy restriction. Nutr. Res. Rev. 3, 49-74.

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