Fat breaks down into glycerol and fatty acids, and both of these substances end up producing carbon dioxide, water, and energy after further breakdown. Fat is one of the main nutrients within the human body and is mainly composed of triglycerides. Under the action of lipase, fat can be broken down into glycerol and fatty acids, of which glycerol will be broken down into 3-phosphoglycerol under the action of glycerol phosphokinase, and then gradually converted into dihydroxyacetone phosphate under the catalytic action of phosphoglycerol dehydrogenase, and finally enter into sugar metabolism. And fatty acids will generate lipoyl CoA under the action of lipoyl CoA synthetase, and then enter the mitochondria with the help of the transferase system, and degrade to acetyl CoA by β-oxidation. Eventually, acetyl CoA will be oxidized to carbon dioxide and water after passing through the tricarboxylic acid cycle, of which carbon dioxide will be excreted through respiration, while water will be excreted through sweat and urine. Therefore, in order to maintain a good figure, then we must promote the body fat metabolism, through various ways to make the consumption of calories than the intake of calories, such as reasonable control of diet, appropriate aerobic exercise and so on.