A triacylglyceride (also called TAG, triglyceride, triglycerol, or triacylglycerol) is a type of fat or oil. Triacylglycerides are the main energy source in the body. They are stored in fat tissue called adipose tissue. Body fat in humans and animals and vegetable oil contain triglycerides. Triglycerides are found in the blood and in fat cells.