How Calories Really Count
Last summer, Mark Haub, Ph.D, an associate professor of nutrition at Kansas State University, made headlines when he lost 27 pounds after two months of living on Twinkies, Ho-Hos, Little Debbies, and other convenience-store snack cakes.
Haub's experiment reinforced the calories-in/calories-out equation: If you drastically cut back—as Haub did, from 2,600 to 1,800 calories per day—you will lose weight, no matter how nutrient-deprived your diet may otherwise be. Anyone who knows what calories are—units of energy—knows this to be so.
But lost in the brouhaha surrounding the so-called Twinkie Diet was a more interesting trend: a revision of the idea that all calories are equal. New studies hint that the body may burn calories from whole foods better than it does calories from processed foods like Twinkies. Essentially, it appears the body can "burn" a bit hotter on whole foods and use healthier fuel at the same time. That's great news for people who want to follow the new Dietary Guidelines, because it addresses two big problems with the American diet: calorie overload and nutrient inadequacy.
While Dr. Haub was carefully counting his Twinkie calories, a group of scientists from Pomona College in California were preparing to publish a small study with interesting implications for anyone who wants to maintain a healthy weight and eat good food.
The researchers fed people two meals with the exact same number of calories; the only difference was how much the food was processed. Group A was treated to sandwiches made with real cheese on whole-grain bread; Group B made do with processed cheese on fiber-stripped white bread. The results, published in Food & Nutrition Research, found that the processed meal decreased the rate of diet-induced thermogenesis—the number of calories you burn when eating and digesting—by nearly 50% compared to the meal made with whole foods.
The calories burned from a single sandwich may be small, but this rise in metabolism caused by whole foods (known as the thermic effect) might account for about 10% of a typical person's daily calorie expenditure. Although more research is needed, early indicators show that whole foods may offer a real metabolic advantage for calorie counters. Whole foods aren't just better for you because they're more nutritious, but they also may be, essentially, lower-calorie.
Weight Watchers, recognizing the differences in how our bodies react to calories—and nudging dieters to eat more whole foods—revamped its points system late last year to make fresh fruits and most vegetables "free." Eat all you want, the WW plan says. In general, foods higher in fiber and protein were assigned fewer points, and processed foods were given more.
All this comes at a time when calories are back in the nutrition spotlight. The fat-phobia and obsessive carb-counting eras are waning. Governments are talking about "soda taxes" to combat the health costs of consuming too many "empty" calories. Calorie labeling is showing up—voluntarily and by law—on more restaurant menus, and calorie counts are more prominent on some food labels.
This calorie consciousness is a good and a bad thing. Most Americans do need to cut back on calories. Balancing energy in and energy out (which brings in the whole question of exercise) is critical to solving the obesity crisis. But calorie counting per se is tedious and not the real answer, unless you want to go on a Twinkie diet. The better approach is the whole foods approach, because Americans also need to increase intake of a long list of nutrients, including fiber, potassium, calcium, and vitamin D, which are associated with whole foods. Eating more fruits, vegetables, and whole grains delivers those nutrients in a form that may also hold a calorie-burning advantage.