Eat more, weigh less. Sound too good to be true? Naturally, there’s a catch or two. You still have to exercise, and you may have to change the way you assess the suitability of food.
According to Barbara Rolls, author of this year’s “Volumetics,” you can indeed consume a greater volume of low-energy foods without increasing calories. And the greater volume leads to a feeling of fullness, or satiety. And, as we all know, feeling hungry is one of the biggest obstacles to successful weight loss.
Beyond that, gaining back lost weight is one of the biggest disappointments after a successful diet. The approachwhich includes regular exercisepromises that you can feel full, lose weight and sustain that weight loss.
The theory is based on research done by Rolls at the University of Pennsylvania, and by Dr. Roland L. Weinsier at the University of Alabama at Birmingham.
Rolls, who holds the endowed Guthrie Chair of Nutrition at Pennsylvania State University, has spent more than 20 years researching hunger and obesity.
Among her findings: Fat plays a smaller role in satisfying hunger than previously thought. Instead, it’s the weight, or volume, of food that seems to matter. So long as dieters eat the same volume day after day, they can choose less caloric foods–or less “energy-dense” foods–and still avoid the hunger monster.
“Fat packs two times as many calories per gram than protein or carbohydrates,” Rolls says, “but when it comes to how full the feeling, we found very little difference in meals with high fat, unless you go down to practically no fat content at all. There is very little data to support the fat-satiety connection.”
What is “energy density”? It’s a scientific-sounding phrase for a simple concept: Foods lower in energy density have fewer calories per given weight than do foods higher in energy density.
The combination of elements in a food–fat, carbohydrate, protein, fiber and water–determines energy density. An example: 1/4 cup of raisins and 1 2/3 cups of fresh grapes each have 100 calories, but no fat. Which fat-free food makes you feel fuller? The grapes. Here’s another one: One fresh tomato has 25 calories; so do fat-free pretzels–but only 1/4 ounce of them, about 5 tiny pretzel sticks. Ounce for ounce, fat-free pretzels have about 20 times as many calories as tomatoes. (Notice that grapes and tomatoes have lots of water and fiber. Raisins are high in fiber but low in water content. Pretzels are low in water and fiber.)
“We eat according to the weight of food, not calories or fat content,” says Weinsier, who has been using these principals to help people lose weight for 25 years. “If I eat French fries, a soda and a cheeseburger–a high-energy-density meal–by the time I have eaten enough weight to feel full enough to get the signal to stop, I have overeaten on calories.
“But if I eat that same weight in a meal composed of whole grains, fruit and vegetables, by the time I get the signal from my body to stop I may have not even eaten enough calories to meet my body’s caloric needs.”
Rolls believes that energy density–or calories in grams, expressed in a single number–is so important that it should be added to every food that carries a Nutrition Facts label. Which is to say, most packaged foods.
How the system works
– Maintain your usual volume of food, but eat foods low in energy density, which means you will consume fewer calories and feel just as full.
– Learn to recognize foods high in energy density (see list). A high-fat diet promotes weight gain because fat is high in energy density. But many low-fat foods are high in energy density as well. So cutting fat won’t help you lose weight unless you also limit low-fat or fat-free foods that are high in energy density.
– Water content of food plays a major role in controlling hunger. So to lower the overall energy density of your diet, eat more foods high in water, such as cooked grains, fruits, vegetables, soups and stews.
You don’t have to deny yourself all energy-dense foods. Just eat more meals and snacks that are lower in energy density and enjoy reasonable (OK, smaller) portions of energy-dense favorites.
Lowering the overall energy density of your diet, along with regular exercise (and some behavior management), can result in significant weight loss that is sustained over time.
But what about the notion that a consistently high volume of food could stretch your stomach over time, thus undoing all this hard work? Can your stomach stretch or shrink?
Yes, according to Dr. Allan Geliebter, a research psychologist at the obesity research center of St. Luke’s Roosevelt Hospital in New York City. His studies of bulimic individuals (who binge and purge) found that they do gain stomach capacity. And, in studies done with people on a very low-calorie diet (600 calories a day), their stomach capacity shrank by 30 percent. Geliebter’s strategy: “Eat low-energy-density foods, but have smaller meals, and more meals a day, maybe more than three.”
The University of Alabama’s Weinsier was the first to look at the relationship between energy density and weight loss. He began his program (still going strong today) in 1976. In 1983 he showed that people who stayed on a weight-loss plan low in energy density maintained the lost weight, and 80 percent of them were at or below their new body weight two years later.
“The program is effective in people who are mildly overweight–or massively obese. And it works in men and women,” he says. But he adds, “Twenty percent of the people put all their weight back and then some.”
What accounts for those total failures? Neither Rolls nor Weinsier can say for sure. There are few long-term studies on weight maintenance and the role of exercise. But both believe that exercise is essential to keeping weight off.
And Rolls stresses the importance of behavior modification (see accompanying story). “Change takes effort,” she says. “If you’re 40, and eat five meals and snacks a day, you’ve done so 70,000 times by now.” And if the foods you’ve been eating have been high in energy density, that’s a powerful habit to break.
Succeeding at losing
Weight management experts have developed behavior modification approaches that are proven to make lifestyle change easier, and author Barbara Rolls believes that if you use them, chances are you’ll lose more weight than if you simply try to change your eating habits. “You’ll also increase your chances of keeping the weight off,” she says.
Rolls offers seven proven behavior modification strategies:
1. Keep a food and exercise log.
2. Identify cues for overeating and underactivity: If you’re a chocoholic who likes to eat it while watching TV in the living room, keep it out of the house entirely, or buy just two pieces, not a pound, and decide to eat in another room.
3. Work on constructive thoughts and feelings: Instead of, “I had a doughnut; now I’ve blown my diet,” how about, “OK, so I ate a doughnut; I can still make healthy choices the rest of the day.”
4. Learn stress management: If you overeat in response to stress, it’s easy to override your satiety signals. Some techniques to calm down include deep breathing, progressive muscle relaxation, meditation and (of course) exercise.
5. Get more involved with family and friends: People with social support do better in weight management.
6. Exercise! Do something on a regular basis to move.
7. Plan for setbacks: Some days are better than others; no one loses weight every day. It helps to think ahead how you’re going to handle eating situations that trigger diet relapses.
And she recommends that the best way to lose weight is to consume 500 fewer calories a day while increasing activity. That leads to a weight loss of about one pound a week. “Losing one to two pounds a week is the best rate for long-term success. Lose weight faster, and you’ll simply regain much of it.”
Who you calling dense?
Here’s how Rolls and other nutritionists calculate foods’ energy density: Calories divided by grams equals energy density. So if a slice of bread that weighs 28 grams (about an ounce) has 70 calories, its energy density is 2.5 (70 divided by 28). Simple, huh?
Foods very low in energy density (less than 0.6): Most fruits and vegetables, skim milk, and broth-based soups.
Foods low in energy density (0.6 to 1.5): Many cooked grains, breakfast cereals with low-fat milk, low-fat meats, beans and legumes, low-fat mixed dishes and salads.
Foods medium in energy density: (1.5 to 4): Meats, cheeses, high-fat mixed dishes, salad dressing, some snack foods.
Foods high in energy density (4 to 9): Crackers, chips, chocolate candies, cookies, nuts, butter, and full-fat condiments.
