Eat more weigh less
The answer may lie in the new science of 'volumetrics'
Once at Pritikin, Kenney suggested the center change its emphasis from the low-fat regimen that the program had been founded upon to one emphasizing a lower-caloric-density approach. Kenney was fearful that the wave of low-fat but high-energy-dense cookies, crackers, and snack foods hitting the market would lead to more obesity and confuse the public about the usefulness of reducing fat calories. "And that's just what happened," he says. "In the 1990s, we saw Americans gaining weight like never before . . . . The public has been oblivious to the very important role calorie density plays in how full people feel when they eat a set amount of calories."
Of course, a small group of elite dieters who attend some of the premier weight-control centers have been schooled in energy density. At the Duke Diet and Fitness Center, as at Pritikin, nutrition manager Elisabetta Politi has been using an energy-density approach for a few years. "I think Barbara Rolls has a great theory, and there is a lot of interest in it," says Politi. "We take advantage of what she's found in what we do here. We start with a big salad, soup, smaller servings of protein and higher-density foods; and our clients feel satisfied on 1,200 or 1,300 calories a day." Likewise, Brian Zehetner, the lead nutritionist at Canyon Ranch SpaClub at the Venetian in Las Vegas, says, "We promote foods that are high in fiber and water. They add bulk, but it's not calorie-containing bulk. So theoretically, you can decrease your calorie intake and eat more food while eating low-energy-dense foods compared to eating high-energy-dense foods." Rolls wants Volumetrics to be accepted by a wider audience, however. She's now on the board of the Jenny Craig weight-loss program, and she notes that Weight Watchers seems to be incorporating aspects of Volumetrics as well, though she quibbles with both of these programs.
Paradigm. If the majority of the public, outside of a few weight-control programs, has been oblivious to the role energy density could play in cleaning up the American diet, so have many nutritional scientists. "This is a paradigm shift," agrees Gary Foster, clinical director of the Weight and Eating Disorders Program at the University of Pennsylvania School of Medicine. Volumetrics is "an overarching concept, less based on macronutrients, though clearly, high-fat foods have higher energy density. It's a more unifying approach to diet, and there are data to support it." The downside, Foster says, is that energy density is not listed on food labels. Rolls hopes that will change: "If we had an energy-density number on food labels, it would give people an immediate way to compare foods and the calories in a portion."
"My sense is people are becoming disenchanted with a low-carbohydrate diet, which is a high-energy-dense diet," says Columbia University's Xavier Pi-Sunyer, a member of the dietary guidelines advisory committee and director of the Obesity Research Center at St. Luke's-Roosevelt Hospital Center. "So this would be a return to a lower-energy-density diet. And that is in line with the new guidelines."