Triglycerides play an important role in metabolism as energy sources and transporters of dietary fat. They contain twice as much energy as carbohydrates and proteins. In the intestine, triglycerides are split into glycerol and fatty acids, which are then absorbed into the cells lining the intestines, packaged together with cholesterol and proteins, excreted the lymph system and transported to the large vessels near the heart before being mixed into the blood. From there, triglycerides can be released to be used as a source of energy.
Fat and liver cells can synthesize and store triglycerides. When the body requires fatty acids as an energy source, the hormone glucagon sends a message to release free fatty acids.
As the brain can not utilize fatty acids as an energy source, the glycerol component of triglycerides can be converted into glucose for brain fuel. Fat cells may also be broken down for that reason, if the brain's needs ever outweigh the body's.
