"More than 90 percent of the U.S. adult population reports consuming low- or reduced-fat foods and beverages, many of which contain fat substitutes, yet the number of overweight individuals continues to increase," says Judith Wylie-Rosett, Ed.D., R.D., a member of the American Heart Association's Nutrition Committee and author of the statement.

"The bottom line is that foods made with fat substitutes, used in moderation, may provide some flexibility in food selection, but are not an effective strategy on their own for weight control. Often, reduced-fat versions of products have the same or even more calories than their full-fat versions," says Wylie-Rosett.

The statement aims to clarify the role of the fat substitutes used in many food products and provides information on the pros and cons of including them in the diet.

Fat substitutes seem to have led to an overall trend for less fat in the diet. Americans have nearly met the government's population-wide goal of reducing fat consumption to no more than 30 percent of total calories. A 1988-1991 government survey showed that Americans consumed about 34 percent of total calories from fat, compared with 40 to 42 percent of total calories in the 1950s.

"We've done well in getting out the message about reducing fat intake," says Wylie-Rosett. "Now we must put the emphasis on obesity, which has doubled in the last 20 years. During the 1990s the number of people in the United States with diagnosed diabetes increased by about 33 percent. Almost all of this increase is related to the rise in obesity.

"The problem is that the plethora of 'fat-free' products has led to consuming more sweet rolls, cookies and frozen yogurt," says Wylie-Rosett. "A healthy diet, like the one recommended by the American Heart Association, doesn't just limit fat, but also emphasizes foods such as fruits, vegetables, whole grains and other foods that have positive benefits for your health, such as dietary fiber, vitamins and minerals."

Thirteen kinds of fat substitutes were examined -- six derived from carbohydrate, two from protein, and five from fat. Those formulated from carbohydrates such as polydextrose and gums or protein such as modified whey have little or no effect on digestion, absorption, or metabolism of vitamins and minerals. Some fat-based substitutes, such as caprenin and salatrim, used in baked goods and dairy products, also appear to have no deleterious effect on metabolism.

The statement raises concern about Olestra, a fat-derived fat substitute. Olestra reduces the absorption of fat-soluble vitamins. To compensate for this, the manufacturer must add these vitamins into Olestra-containing foods. Little is known about potential interactions between Olestra and medications and ingredients in food products that can affect fat-soluble nutrient movement and absorption rates in the gastrointestinal tract. Olestra has also been shown to affect stool composition -- 40 grams of olestra can result in a misdiagnosis of malabsorption.

The Association's dietary guidelines for healthy individuals still recommend limiting total fat to less than 30 percent of total calories, with only 10 percent (7 percent for those with known cardiovascular disease) coming from the combination of saturated fats and trans fats.