it's chemically metabolized, that is, broken down into simpler molecules and these chemical breaks release heat (calories) most of the simple molecules are either recycled in the body, filtered out by the liver or kidneys and passed through urine or feces. But I believe the majority of the simple molecule are recycled. But I'd bet sweating plays a role in getting rid of the byproducts.
When you consume fewer calories than your body needs, your body turns to fat for energy. Your fat cells (triglycerides) provide the fuel for this energy.
Through a series of complex metabolic processes, triglycerides are broken down into two different components — glycerol and fatty acids — which are absorbed into your liver, kidney and muscle. Here, these components are further broken down by chemical processes that ultimately produce energy for your body.
The heat generated through these activities is used to help maintain your body temperature. The waste products that result are water and carbon dioxide. You excrete water primarily in urine and sweat and carbon dioxide in air exhaled from your lungs.
Nice one SG. Now can you tell why:
When I drink, say, a litre of water (which weighs about a kg) and weigh myself before and after, why my mass hasn't increased by a kilo?
I have very accurate bathroom scales btw.