Ask Dr. Sears defines hydrogenated fat as a fat that results from the process of hydrogenation, which is when hydrogen molecules are forced into a normally unsaturated fat molecule. About.com Nutrition states that this process changes the shape of the fat molecules and gives the oil a semi-solid or solid texture.
According to Ask Dr. Sears, using hydrogenated fats is advantageous because they have a longer shelf life and they are cheaper. Hydrogenated oils are commonly used in processed foods such as cookies, peanut butter, margarine, cakes, shortening, chips and crackers. Hydrogenated oils are also used for frying in restaurants because they stand up well to heat and last longer.
Despite their advantages of cost and convenience, Ask Dr. Sears states that hydrogenated oils have several negative health effects. Nutritionally, hydrogenated fats are not useful to the human body. Hydrogenated oils contain trans-fatty acids, which have been shown to raise LDL, or bad cholesterol levels and to lower HDL, or good cholesterol levels in the blood. Trans fats may also reduce the body's ability to metabolize fats that the body needs and decrease the body's ability to fight inflammation. Consuming hydrogenated fats may also lead to a decreased intake of other essential fatty acids that are important to organ function.