To Your Health

Q. I'm jealous of my friend who can eat a lot of high-fat foods without gaining weight. It seems that any fat I eat goes straight to my hips. Why can't I just completely eliminate fat from my diet?

A. Fat is essential to all life forms, and the perception that all fat is bad is misleading. Not only does a thin layer of fat form the membranes that separate the insides of living cells from the outside, but also powerful hormones are formed from certain essential fats. In many ways our health depends on both the amount and the specific kind of fat in our diet.

In nature, fat is usually found in the form of either triglycerides or phospholipids. Triglycerides, composed of three fatty acids attached to glycerol, are the familiar form of solid fat or liquid oil. Phospholipids are the less obvious fat found in the membranes of life forms, in which a phosphate compound of some sort replaces one of the fatty acids. There are at least 30 different fatty acids and several phosphate compounds that can combine with glycerol to form a unique fat or phospholipid, and because there is a wide variety of combinations some fats can be classified as "good fats" and some as "bad fats."

Your friend probably chooses a diet rich in "good fats" and thus maintains proper metabolic control over fat. Overly zealous dietary restriction of fat can actually result in deficiency of fatty acids that eventually manifests itself as disease. In America, the most commonly deficient fatty acids are in the omega-3 family and tend to increase the risk of cancer, heart disease, depression, learning disabilities, and visual problems. Another family of essential fatty acids, less often deficient, usually relates to skin and hair problems, poor wound healing, susceptibility to infection, kidney degeneration, and sterility.

While some "essential" fats must be obtained from the diet, our bodies have the machinery to make and modify many other fats. When dietary fat is restricted too severely, resulting in deficiency in certain essential fatty acids, the body will manufacture the closest possible substitute fat to the one that is missing. Often that substitute fat will work for the membrane function of the needed fat but not for hormone production and conditions such as rheumatoid arthritis may ensue.

The good news is that both health-care providers and the public increasingly appreciate the value of the right balance of fat, and in the future it will become easier to obtain the kinds of fats we need. As published in the European Journal of Clinical Nutrition in May of 2002, researchers in New Zealand have manipulated the diets of cows to produce butter that will actually lower "bad" or LDL serum cholesterol levels. At Texas A&M University, beef with a fatty acid composition resembling that of fish has been produced. Eggs with an enhanced level of omega-3 fatty acids have been available commercially for years.

Even now, you can replace the saturated fats and hydrogenated oils found in convenience foods with the rich sources of healthy fats found in whole foods. Don't expect overnight changes, but in the long run your body will respond favorably.