A triglycerides test measures the amount of triglycerides in your blood. Triglycerides are a type of fat in your body. If you eat more calories than you need, the extra calories are changed into triglycerides. These triglycerides are stored in your fat cells for later use. When your body needs energy, triglycerides are released into your bloodstream to provide fuel for your muscles to work. If you eat more calories than you burn off, especially calories from carbohydrates and fats, you may get high triglyceride levels in your blood. High triglycerides may put you at greater risk for a heart attack or stroke.