Not only does the fat you eat help you enjoy your food and feel satisfied after meals, but it also plays important roles in your body. You store some of it for long-term energy needs and use some for short-term energy. Additionally, it stores help cushion vital organs and protect nerve cells. Most of the fat you eat, digest, and metabolize is in the form of triglycerides.
Digestion Step 1: Your Mouth and Stomach
Fat digestion begins when a gland under the tongue secretes the fat-splitting enzyme lingual lipase. Gastric lipase, secreted by cells in the stomach, continues working on the fat molecules as the muscles of the stomach wall act like a blender, churning and mixing stomach contents. Together, this emulsifies the fat by breaking up large fat globules into smaller ones, distributing them evenly. It takes your stomach longer to digest fats than carbohydrates or protein, so higher fat meals may make you feel fuller for a longer period.
Digestion Step 2: Your Small Intestine
Most fat digestion happens once your food passes from the stomach to the small intestine. In the upper part of the small intestine, the duodenum, mechanical emulsification continues with the help of bile acids released from the gall bladder, where they are stored after being produced by the liver. Pancreatic lipase, an enzyme secreted by the pancreas, then splits triglycerides apart into smaller parts called diglycerides, monoglycerides and free fatty acids.
Absorption and Transport:
Further down the small intestine, these smaller components are absorbed by the layer of cells lining the intestinal wall. Smaller fatty acids go straight to the portal vein where they bind to the protein albumin and travel to the liver to be used for energy or turned into longer chains as needed. Larger fatty acids are reformed into triglycerides, then are packaged into lipoproteins called chylomicrons and released into the bloodstream.
The triglycerides that travel to your liver, muscle, and fat tissue are once again broken down into free fatty acids and glycerol. The fatty acids can enter your cells and burn as a fuel source, or they can incorporate into tissue for later use. They can also become a part of cell membranes, and they can serve as precursors for additional lipid-rich biological molecules necessary for cell signaling and inflammation reactions. The remaining glycerol recycles in the liver and kidney in preparation for forming a new triglyceride with additional free fatty acids.
This was all about the process!