http://www.nytimes.com/2004/10/05/health/05brod.html

With Fruits and Vegetables, More Can Be Less
By JANE E. BRODY

Published: October 5, 2004

What determines how much we eat and how much we weigh? Is it the
amount of fat in foods, the presence of carbohydrates, the size of our
portions, what we drink with our meals, that elusive trait called
willpower? Conflicting popular advice can prompt would-be dieters to
give up before they even start.



The good news based on solid research is that you can eat more -
probably more food than you're now eating - and weigh less, if you
choose more of the right kinds of foods.

At a recent meeting on the worldwide obesity epidemic, important
insights into successful weight management were offered by Dr. Barbara
J. Rolls, a professor of behavioral health at Penn State. She began
her presentation on weight control with this irrefutable statement:

"Calories count, no matter what you read in the press. The laws of
thermodynamics have not been reversed."

With respect to weight gain and loss, the laws of thermodynamics can
be translated as: Calories consumed must be used or they will be
stored as body fat. The body does not waste energy, no matter what its
source. When people are placed on carefully controlled
calorie-restricted diets, the amount of fat in the diet - whether 25
percent or 45 percent of calories - has little effect on weight loss,
Dr. Rolls reported.

People who claim that they can eat as much as they want (of protein
and fat, for example) and lose weight as long as they avoid certain
kinds of foods (carbohydrates, for example) are really eating less
(that is, fewer calories) than they did before.

But what about a majority of people concerned about weight control who
are not interested in cutting out breads, cereals, grapes, bananas,
watermelon, carrots, beets, potatoes, rice and pasta (not to mention
wine, beer, cakes, cookies, ice cream and other carbohydrate-rich
foods banned on Atkins-style diets)? Are they doomed to remaining
hopelessly overweight?

Not according to Dr. Rolls, an expert on satiety and satiation, words
that refer to what and how much a person has to eat at a meal to feel
satisfied and stop eating. Many characteristics of foods affect
satiety: how they look, taste and feel in the mouth; how much chewing
they require; the nutrients they contain; how densely packed the
calories are, and, independent of caloric density, the volume of food
consumed.

She does not dispute the popular premise that the "macronutrients" in
foods - protein, fat, carbohydrates, alcohol and fiber - influence
caloric intake and use. For example, calorie for calorie, protein
appears to be the most satiating nutrient. Furthermore, during
overeating, the body burns more calories to metabolize protein and
carbohydrates than it does when processing fats, which are the
nutrients most efficiently stored as body fat.

Food Volume Counts

So what makes your body say you've eaten enough? Dr. Rolls's studies
on satiety have clearly demonstrated an overriding influence of food
volume, prompting her to write an excellent book, "The Volumetrics
Weight-Control Plan: Feel Full on Fewer Calories" (HarperCollins,
2000) with Robert A. Barnett.

She found that the amount of calories in a given volume of food makes
a big difference in how many calories people consume at a given meal,
and throughout the day.

In nutritional parlance, this is called the energy density of the
food.

The greater the energy density - the more calories packed into a given
weight or volume of food - the easier it is to overeat.

"People tend to eat a consistent weight of food," Dr. Rolls has found.
When consuming a calorie-dense food high in fat, people are likely to
eat more calories just to get in a satisfying amount of food.

What increases food volume without adding calories? You guessed it.
Water. And what foods naturally contain the most water? You got that
right too. Fruits and vegetables.

"People given the message to eat more fruits and vegetables lost
significantly more weight than those told to eat less fat," Dr. Rolls
said. "Advice to eat more is a lot more effective than advice to eat
less. Positive messages about what can be eaten are more effective
than restrictive messages about what not to eat."