When You Lose Weight, Where Does the Fat Go?


Quick Answer

When you lose weight, complex metabolic processes convert fat into usable forms of energy. Using the energy generates byproducts that are excreted in the form of exhalation, sweat and urine.

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Full Answer

All fat, whether solid or liquid, is found in a form known as a triglyceride. The body breaks down triglycerides to produce the glycerol and fatty acids used in energy metabolism or fat tissue storage. Fatty acids are vital in the citric acid cycle and electron transport chain that produces large amounts of energy. The consumption of excessive calories combined with a sedentary lifestyle causes triglycerides to be stored in fat tissue.

When losing weight, a hormone known as lipase begins to break down stored fat in a process called lypolysis. Tissues throughout the body metabolize the stored fat and produce carbon dioxide, water, heat and adenosine triphosphate. The lungs expel carbon dioxide through exhalation. The body expels water through urine and perspiration. The heat produced helps maintain body temperature. The adenosine triphosphate is used throughout the body in muscle movement and organ function. As the body relieves cells of glycerol and fatty acids, the fat cells get smaller. In cases of moderate weight loss, the skin's elasticity allows it to shrink to fit the body's new size. However, rapid weight loss can outpace skin elasticity and result in loose, extra skin.

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