Cracking the Vault: Subtraction Equals Addition

Americans are often encouraged to eat more of this or less of that. If a nutrient being subtracted from the diet contains calories, simply reducing it will leave a calorie deficit. While this may be desirable for most Americans, research suggests that advice to reduce calorie intake is rarely followed for long. This is because a reduction in calorie intake tends to increase hunger. People will usually compensate for eating less of one type of food by eating more of something else. Therefore subtracting any calorie-containing food or ingredient from the diet is likely to result in adding more calories from something else. If one tries to eat less fat, one could easily eat more carbohydrates or vice versa.

Subtraction equals addition

Nutrition researchers usually try to study the effects of replacing one caloric component in the diet with another. If a study reduced saturated fat in the diet but didn’t replace those calories with something else, then the metabolic changes observed could be due to either the drop in calorie intake or the reduction in saturated fat or both. Under such circumstances, one could not draw any conclusions about the effects of simply subtracting saturated fat from the diet because the reduction in calorie intake and the resulting loss of weight could very well be primarily responsible for any metabolic changes observed. So studies on the effect of saturated fat on blood lipids are always designed so that the calories from saturated fat are replaced by something else, such as starch, unsaturated fat or sugar. The subtraction of saturated fat from the diet almost always means adding an equal number of calories from some carbohydrate and/or unsaturated fat.

Limiting dietary fat is too simplistic.

Advice to the public to limit dietary fat and saturated fat is currently recommended by the American Heart Association, the National Cancer Institute, and the U.S. Dietary Guidelines. However, foods are never 100% saturated fat; only refined fats and oils are 100% fat calories. It seems likely that when the federal government and various health advocacy groups suggested Americans eat less fat and saturated fat, they had hoped Americans would replace fatty meats, desserts, and dairy products with more high-carbohydrate foods like fruits, vegetables, beans, and whole grains. This is not what happened. Why? Americans were bombarded with ads for fat-free foods such as cookies, cakes, candies, chips, and nonfat frozen yogurt. Most of these are widely advertised low-fat and fat-free foods that contain little in the way of vitamins, minerals, fiber, and phytochemicals. Instead, these manufactured foods are nearly devoid of these valuable dietary components that would be found in a healthy diet containing fruits, vegetables, beans, and whole grains.

Low-fat foods are often higher in salt and sugar.

Many low-fat foods have even higher salt and refined sugar levels than their higher-fat alternatives. On an equal calorie basis, low-fat salad dressing, chips, and cheeses are almost always higher in salt. Fat-free cookies, cakes, and muffins are always much higher in sugar than their higher-fat counterparts. Are these fat-free? foods do not have any more healthy things than their higher-fat versions and often have a similar high-calorie density. A lack of fiber and a high-calorie density yields high-carbohydrate foods with far less satiety value than natural high-carbohydrate foods. As a result, eating more of these highly refined and processed high-carbohydrate foods has certainly not helped overweight Americans lose excess body fat.

Americans are, in fact, getting fatter on a lower-fat diet. There seems to be a growing interest in higher-fat foods, and much research suggests that Americans might be better off adding monounsaturated fat. But this is not true. In the 1980s, it was demonstrated that people eat more calories and gain weight when fat is added to foods. We now know that this is because the added fat increases the calorie density and lowers the satiety value of the food. It is becoming increasingly clear that simplistic advice about adding or subtracting fat or carbohydrate is useless. Foods with a lot of saturated fat or hydrogenated fat raise LDL levels and promote cardiovascular disease, obesity, and diabetes. Foods high in sugar and/or refined flour also promote obesity and diabetes. Foods high in refined carbohydrates may be even more calorie-dense and contain far lower levels of vitamins and minerals than some higher-fat foods like fish, avocados, tofu, meat, and milk. As such, they promote obesity and diabetes, increasing cardiovascular disease risk.

The bottom line:

Americans must be encouraged to add more fruits, vegetables, whole grains, beans, fish, and nonfat dairy to their diet and subtract foods high in salt, saturated fat, hydrogenated fat, and/or refined carbohydrates to their eating plan. This would result in a much higher nutrient, fiber, and phytochemical content than the typical American diet. It lowers calorie density and increases satiety value. When these foods are added, and the foods high in unhealthy fats and/or refined carbohydrates/sugars are subtracted from the diet, calorie intake falls, arteries don’t clog up, and people lose weight and keep it off without hunger. Plus, the death rate for heart attacks, strokes, cancer, and diabetes will fall.

By Dr. James J. Kenney, PhD, RD, FACN.