The typical western diet is fairly rich in carbohydrates and fats even though the 2010 Dietary Guidelines from the United States Department of Agriculture recommend lowering the amount of saturated fats and trans fats that Americans ingest. The recommendation that Americans keep saturated fats to less than 10 percent of the calories they consume daily is an effort to slow the obesity epidemic and heart disease. Understand how your body digests and metabolizes fat and ultimately provides you with energy.
The Mouth
When you place food in your mouth such as meat or vegetables, they are not in a form that the body can immediately use. Food needs to be broken down into smaller particles. This begins with chewing and the release of saliva. Saliva comes from three major glands located inside of each cheek, the bottom of the mouth, under the jaw and towards the front of the mouth. Saliva is a combination of water and enzymes that help to breakdown food. Amylase, lysozyme and lingual lipase help to begin the breakdown of fats and make them easier to swallow.
The Stomach
Once adequately chewed, the food bolus, in this case fat, is swallowed and sent to the stomach for further breakdown. The stomach produces another set of enzymes that produce stomach acid in an effort to break the fat into smaller particles. Food is stored in the stomach until it is adequately broken down and can be sent to the intestine.
The Liver and Gallbladder
The liver produces bile, another type of digestive enzyme specifically meant to breakdown fat. The bile is sent to the gallbladder for storage. When the gallbladder receives a signal saying that there is fat to be digested, it squirts bile into the intestine where it meets up with the fat that has been broken down in the stomach. Bile dissolves fat into a watery substance in order to be further digested by enzymes from the pancreas and intestine.
Absorption and Metabolism
The intestinal and pancreatic juices make the larger fat molecules into fatty acids and cholesterol. These molecules move into the mucosal cells of the intestine where they are formed back into large fat molecules and moved through the system via circulating blood and deposited into various areas of the body. Fat is the last to be metabolized when the body needs energy. Only when the body has used up all of the circulating glucose from carbohydrates will the body turn to its fat resources.
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