Fat replacers are ingredients used in place of fat in food products to lower the fat and calorie content of the food. The body requires fat from food for a variety of functions, such as to obtain energy, transport vitamins, or control body temperature; however, a diet too heavy in fat can cause weight gain, high blood pressure, and heart disease. Fat products such as oil, shortening, and butter are typically high in calories but are responsible for adding a creamy texture and rich taste to foods. Completely eliminating fat in food items may have dense or bland results, so fat replacers are designed to help maintain the texture and taste of foods that are reduced fat or fat-free.
Food engineers make fat replacers in both natural and synthetic forms. The natural varieties typically use protein, carbohydrates, or a combination of the two. Synthetic versions are made from fat that has been chemically engineered so that it contains a lower amount of fat compounds and calories.
Microparticulation is a method in which ground particles are exposed to heat and placed into a vacuum until the particles separate further. Fat replacers made from protein use whey, the liquid layer that forms when milk is left to curdle. Once the whey is put through the microparticulation process, the separated particles mimic the creaminess that fat adds to food. They are often used as a substitute for the fat in salad dressings, dairy products, and soups.
Carbohydrate versions of fat replacers usually use items that act as natural thickeners, such as oats, xanthan gum, pectin, and celluloid. These items are also ground and put through the microparticulation process, just like protein-based replacements. Carbohydrate versions help retain the thickness of food items and can be used to replace the fat in baked goods and processed meat products, in addition to salad dressings, dairy products, and soups. Protein and carbohydrate versions may also be combined together to provide the closest resemblance to real fat.
Synthetic fat replacers are used primarily to make low-fat or fat-free versions of actual fat products, such as butter, margarine spreads, and cooking oils. Food engineers often chemically process the full-fat versions and extract the dietary fat compounds and calories. They also can engineer synthetic fat products so that the body cannot absorb the fat; however, these products can potentially cause loose stools and digestive problems in some individuals.
There are potential disadvantages to consuming certain products that contain fat replacers. Some manufacturers may add more sugar or salt to their reduced fat or fat-free products than their full-fat versions in order to make up for some of the richness lost from not using real fat. This may make the products also contain roughly the same amount of calories as full-fat products.