Foods labeled with the number of calories per ounce do not encourage overeating the way that low fat labels do, according to researchers at Penn State. Their findings confirm that low-calorie eating can help people lose weight without affecting how satisfied they feel after eating a meal.

In their study of normal weight women, researchers found that the women ate the same amount of food when their meals differed in calories by as much as 29 percent, even when they were given labels that told them there were fewer calories per portion.

"Some studies have shown that people take larger portions of foods labeled 'low fat' -- using the label as a license to eat more. This study shows that energy density (number of calories per ounce) labels are unlikely to undermine the benefits of offering foods with fewer calories per ounce," said Tanja Kral, doctoral candidate and co-author of the study.

"This tendency of people to take the same size serving of less energy dense foods, even when they know the portion contains fewer calories, offers food manufacturers and restaurants a way to decrease the fat and calories in their products -- making them healthier and satisfying," said Dr. Barbara Rolls, director of the study.

Forty healthy, normal weight women, ages 18 to 32, ate breakfast, lunch and dinner in Penn State's Laboratory for the Study of Human Ingestive Behavior on three days each a week.

They ate the same meals each time: apple bake crisp for breakfast; pasta salad with yogurt dressing for lunch; and Italian pasta bake for dinner. However, the number of calories per ounce of food was changed on each day by varying the amount of apples in the apple bake crisp and the vegetables in the other meals to create low, medium and high energy density meals. The women rated the meals all equally tasteful regardless of their caloric content.

Twenty of the women were counseled on energy density and given a quiz to show they understood the information. These women were then given their meals with a label that showed whether the food was low, medium or high in calories per ounce, the actual value of energy density and the weight and calories per serving. The other 20 women did not receive any training or labels. The eating behavior was similar in both groups despite the training.

Also, the women in both groups consumed about 22 percent fewer calories when their meals were low calorie than when they were high calorie, the researchers reported in the journal Appetite.

The study confirms that eating the usual amount of food but selecting low-calorie foods offers a way to cut back on calories but still feel satisfied.

Other sources: Penn State