Why we like--and eat--fatty foods was the focus of an address by Dr. Adam Drewnowski, PhD, University of Michigan School of Public Health, at a symposium, "Reducing Dietary Fat: Putting Theory Into Practice," held last December in New York City. "Fat is responsible for the textures, aromas, and flavors that make food taste good," said Dr. Drewnowski. " Fat makes food creamy, allows it to retain moistness and gives it good heat transfer properties--all of which contribute to creating the calorie-dense foods people love to eat," he added. Until recently, however, the biological basis for the appeal of fat was unclear.
Naloxone and Food Craving
In a study funded by the National Institute for Drug Abuse, Dr. Drewnowski, professor of environmental and industrial health, and colleagues attempted to isolate the craving for sweet and high-fat foods by administering the opiate blocker naloxone(Drug information on naloxone) (Narcan) to 20 binge-eaters and 20 nonbingers, some of normal weight and some overweight. According to the "opiate" hypothesis of this study, the craving for food may be linked to stress. Researchers found that pleasure in food is mediated by opioid peptides, leading many people to reach for sweets to alleviate stress.
Said Dr. Drewnowski: "Naloxone lowered both the bingers' and nonbingers' consumption of Snickers bars, cookies, M&Ms, and chocolates, while it increased their intake of bland foods. We think that naloxone worked by reducing the overeating induced by taste, that is, by pleasure." In the study, naloxone's blocking action most strongly affected women who said they were addicted to chocolate.
Socioeconomic factors also affect the kind and amount of food a person consumes. By examining world-wide population data from 1969-1994, Dr. Drewnowski demonstrated that the makeup of a country's diet changes as its gross domestic product (GDP) rises. As a country becomes richer, its people gradually increase their intake of meat, milk, sugar, and eggs and eat less grains, potatoes, and complex carbohydrates. Said Dr. Drewnowski: "Among developed countries, greater variety in the diet leads to an increase in the consumption of fat."
Long-term data for Japan, for example, showed that between 1955 and 1990 (parallel with Japan's economic growth), the Japanese ate more dairy products, meats, fruits, vegetables, eggs, fats and oils and smaller amounts of complex carbohydrates. Yet, despite the steady increase, the rate of consumption of fatty foods in Japan was still lower than that in the United States, noted Dr. Drewnowski. With the richer diet and an increase in life expectancy, the populations of developed countries reflect a growth in the number of cases of obesity, cancer , and coronary heart disease. Dr. Drewnowski emphasizes that one's "diet is intricately tied to the chronic diseases one suffers, with richer countries registering higher death rates from cancer and cardiovascular disease." Cancer, he believes, is even more closely linked to diet than heart disease.
In underdeveloped countries, data show that there is also a shift to a more harmful diet, with a sharp increase in the consumption of locally-produced, high-fat soybean products and other oils. For these countries, a rise in diseases induced by higher fat intake could prove disastrous in light of their often inadequate medical facilities.
Yet, says Dr. Drewnowski: "We should not expect people to eliminate certain foods from their diets; it just isn't going to happen." He suggests instead that the food industry begin a significant drive to provide a wide variety of enjoyable low-fat, low-sugar foods. Reducing the amount of fat we eat and lowering the energy of our diets does not have to mean we are consigned to a life of eating without pleasure.