Volumetrics by Barbara Rolls and Robert A. Barnett

Health Facts and Fears reviews the Volumetrics book: “The message is simple: Fill up on fruits and vegetables, which have few calories but have a lot of volume and you'll be likely to eat fewer of the foods that have a higher energy density, or more calories per volume of food. The theory, supported by Dr. Rolls' studies, is that people tend to eat a consistent amount of food. So if you need to eat, say, eight cups of food a day to fill your stomach, the light-weight but calorie-heavy potato chips are going to do little to satisfy your eight cup quota -- and they'll contribute lots of calories while not filling your stomach. You'll still be hungry -- or at least think you are hungry, even though you ate a lot of calories. Yet the same number of calories from apples and carrots would fill you up in no time. Just picture bags of chips instead of the cereal from those commercials that say "You'd have to eat twenty bowls of Frosted Flakes." That would be a lot of calories!

Dr. Rolls, a professor of behavioral health at Penn State, uses more than just sound nutritional science to help people lose weight. She uses psychology too. "People given the message to eat more fruits and vegetables lost significantly more weight than those told to eat less fat," Dr. Rolls told the Times. "Advice to eat more is a lot more effective than advice to eat less (emphasis added)," she said.

Foods with a lot of water -- like soup, melons, tomatoes, and cucumbers -- which have a low energy density will fill you up on fewer calories. So instead of eating less, eat more. Eat big. But eat more of the foods that are filling. And then, when it comes time to indulge on the energy-dense snack, you'll eat it for the taste, not as an attempt to fill your already-full stomach.”
Health Facts and Fears