Trans fat is a kind of fat created when hydrogen is added to vegetable oil, or simply, when certain cooking oils are heated to high temperatures. As everything is done with a purpose, the process of hydrogenation is used to lengthen the shelf life of food and maintain its taste. Unfortunately, trans fat is terribly bad for the body and should not even be taken into consideration for consumption. The primary reason it is so bad for the body is because it raises the amount of LDL (low density lipoprotein), most commonly associated with the term "Bad Cholesterol.," and it lowers the amount of HDL (high density lipoprotein) which is associated with "Good Cholesterol."