For many years, standard nutritional advice has been to eat a variety of foods from several different food groups. The rationale for recommending a variety of foods from the different food groups has been to assure a nutritionally balanced diet. In this century we have seen a dramatic drop in nutritional deficiency diseases like pellagra, scurvy, beri-beri, rickets, etc... But we have also seen a dramatic increase in diseases of affluence. Today half of the adult population in the U.S. is overweight or obese. A wide variety of rich, calorie-dense foods coupled with decreased activity is mostly to blame.Why Fad Diets FailMost everyone has heard numerous anecdotes about how much weight someone has lost on various fad diets. Most of these fad diets severely restrict the variety of foods eaten per day or at least eaten at a given meal. The Beverly Hills Diet had people eating nothing but fruit for several weeks; the Fit for Life diet eliminated food groups like dairy and restricted which foods can be combined at a given meal or eaten at certain times of the day; the Atkins Diet eliminated grains, starchy vegetables, fruits and other high carbohydrate foods. Unfortunately, diets that severely restrict the variety of foods people eat have two major drawbacks. First, such restrictive diets are often nutritionally inadequate because they eliminate whole food groups. Second, even if these diets are made nutritionally adequate with supplements, most people find them too boring and restrictive for long-term success.Human beings are by nature omnivores, which means that we are biologically programmed to desire a variety of foods. No matter how good a nutritionally adequate milkshake such as Optifast or Ensure tastes, people tire of it after a while. Anyone who ate nothing but his or her favorite food for several days would develop a strong desire to eat something else. People often find room for dessert even after they proclaim they can’t eat another bite of a delicious entree. This lack of desire to eat the same thing all the time can reduce the desire to eat and aid weight loss in the short run but backfires over the long run. This is why any weight loss diet that eliminates food groups and/or severely restricts the variety of foods is doomed.Strategies for VarietyThere are two strategies that go beyond “the low-fat, high-fiber diet plus exercise” message to promote weight loss. Both of these strategies work because they increase the variety of healthy foods and decrease the variety and intake of foods that are calorie-dense. Overall, the amount and variety of food eaten is similar, but the amount of calories are decreased without hunger.The first strategy is to choose what we call “preferred carbohydrates.” This generally means consuming high carbohydrate foods such as fruits, grains and starchy vegetables in a minimally processed and less calorie-dense form. For example, fresh fruit would be a good choice but dried fruit and fruit juice would be less desirable choices. Whole wheat pasta, brown rice and hot whole grain cereals would be preferred over bread, dry cereals and crackers because the latter have a much higher calorie density. Yams, baked or boiled potatoes and beans would be preferred over pretzels, french fries and fat free chips because of their lower calorie density.The second strategy is to increase the number of servings of vegetables each day so that they are equal to the number of servings of complex carbohydrates or starchy foods, e.g. if one consumed 7 servings of starchy foods, they would also need to consume 7 servings of vegetables. This recommendation is based on clinical observations; but, a recent study on dietary variety found that an increased variety of vegetables in the diet was associated with lower calorie intake.The bottom line:It is important to eat more vegetables, whole unsweetened fruits and whole unrefined carbohydrates like potatoes, yams, whole wheat pasta, brown rice, hot cooked whole grain cereal, potatoes, beans and yams. Choose nonfat dairy and lean animal protein, especially seafood over their high-fat counterparts.At the same time, it is important to reduce the variety of oils, sweets, fats and/or processed refined carbohydrates like white bread, baked goods, bagels, cookies, crackers, sweetened cereals, chips, pretzels, bread sticks, etc.Dr. James J. Kenney, PhD, RD, FACN