There are three main types of fat. They are saturated, unsaturated and trans fats. Saturated fats come mainly from animal sources such as meat and dairy. At room temperature, saturated fats are solid. Unsaturated fats come mainly from plant sources such as olives and nuts and contain no cholesterol. They are liquid (oil) at room temperature. Unsaturated fats are broken down further in monounsaturated (one double bond) and polyunsaturated (more than one double bond).
You might be asking yourself what a fat is saturated or unsaturated with. A fat molecule (without getting into too much chemistry) is made up of carbon atoms that have hydrogen atoms attached to them.
In saturated fats, all carbon atoms have a single bond to another carbon atom and are also bonded to hydrogen atoms. In unsaturated fats, not all carbons are saturated with hydrogens so double bonds form between carbons. Depending on what carbon the double bond is formed determines the fat’s properties.
Trans fat is man made fat. It is made by taking an unsaturated fat and putting hydrogen through it in a process called hydrogenation. Trans fat is very bad for your health. Whole saturated fat increases LDL (bad) cholesterol and very slightly increases HDL (good) cholesterol, trans fat increases LDL cholesterol and decreases HDL cholesterol.