These fats are used by the body differently than the most abundant fats, long chain triglycerides. MCT's are an easily absorbed energy sounce that do not appear to cause weight gain. MCT's are commonly used for people with malabsorption as they do not require bile acids and pancreatic enzymes to be absorbed and utilized.
MCT's are in theory fats, but they have very distinctive properties. The difference between them and other fats lies in their molecular structure. MCT's are shorter than other fats, which allow them to be burned rather quickly by the body for energy. MCT's enter the mitochondria, without assistance, and do not require the usual transport mechanism.
known as the "fatless fat", these fat molecules are easily mobilized in the bloodstream to provide long-lasting energy, rather than being stored as fat. They also help limit the conversion of excess carbohydrates into fat. One of the "Lean Lipid" ingredients in Muscle Milk.