QUESTION: The more I read about fats the more I realize how bad they are for the body. Maybe you could help me understand why we even have fats in the diet. Should we avoid them completely? Any information you could give me would be appreciated.

ANSWER: I can understand your confusion. Almost every newspaper and popular magazine has published articles about fats, and they all seem to emphasize the negative aspects of this important nutrient. In this column I will try to help you understand how important fat is to the well-being of the body and tell you some of its functions.I will take some of the material I use from an article "Sorting Out the Facts About Fats," published in "Food Insight" by the International Food Informational Council (Winter 1988).

Technically, we should refer to "fats" in the plural, since there is no one type of fat. Fats are composed of the same three elements as carbohydrates - carbon, hydrogen and oxygen. However, fats have relatively more carbon and hydrogen and less oxygen. The most common fat in the diet is a triglyceride. This fat is composed of a backbone structure of glycerol and three fatty acids. The different characteristics of certain fats come from the differences in the fatty acids they contain. Some fatty acids are saturated - that is, they have hydrogen on every carbon - and others are unsaturated. In general, those containing a majority of saturated fatty acids are solid at room temperature and those with a majority of unsaturated fatty acids are liquid at room temperature. There are several major functions of fats in the body:

- Source of energy. Like carbohydrates and protein, dietary fat is an important source of energy for the body. At rest, about half of the energy we use is from fats. During exercise, the amount of energy depends on how hard we work. For instance, with extremely high levels of work, the body burns carbohydrates almost exclusively; with moderate work, the amount of energy from fats increases as the duration of exercise increases. Fats contain much more energy per gram than either carbohydrates or proteins, so that we can store more energy without too much bulk. The body uses whatever fat is needed for energy, and the rest is stored in various fatty tissues. Although some fat is found in the blood and other body cells, most storage occurs in fat cells.

- Essential fatty acids. Certain fatty acids are necessary for proper growth in children. Fat also is required for maintenance of healthy skin, regulation of cholesterol metabolism and as a precursor of prostaglandins, hormone-like substances that regulate some body process.

- Fat soluble vitamins. Dietary fat is also needed to carry the fat-soluble vitamins, A, D, E and K, and aids in their absorption from the intestine.

- Insulation and cushioning. Fat tends to insulate the body both from extremes in temperature and outward shock. It also supports and cushions certain body organs. As you can see, fat is an important substance in many normal functions of the body and is in this sense essential for life.

Next week I will conclude this discussion on fats.