A study conducted by researchers at Penn State has shown that people who eat low-calorie soup before a meal tend to reduce their total calorie intake at lunch (soup + entrée) by 20 percent, when compared to the times they did not eat soup.
Dr Barbara Rolls, who holds the Guthrie Chair of Nutrition at Penn State, said that the study was undertaken to find out if different forms of soup might have different effects on food intake.
"Earlier work suggests that chunky soup may be the most filling type of soup, so the purpose of this study was to determine whether different forms of soup might have different effects on food intake," she said.
As a part of the study the researchers tested whether the form of soup and the blending of its ingredients also affected food intake and satiety. All of the soups tested in the study were made from identical ingredients: chicken broth, broccoli, potato, cauliflower, carrots and butter.
However, the methods used to blend the ingredients varied, so that the form of the soup changed. Soups tested included separate broth and vegetables, chunky vegetable soup, chunky-pureed vegetable soup, and pureed vegetable soup.
While researchers thought that increasing the thickness or the amount of chewing required may have made certain forms of soup more filling, results of the study show that low-calorie soup is filling regardless of its form.
Julie Flood, a doctoral student in nutritional sciences at Penn State, and co-author on the research revealed that the work added weight to earlier studies that consuming a first-course of low-calorie soup, in a variety of forms, can help with managing weight.
"Consuming a first-course of low-calorie soup, in a variety of forms, can help with managing weight, as is shown in this research and earlier studies. Using this strategy allows people to get an extra course at the meal, while eating fewer total calories," says Flood.
However, she warns that people still need to be careful about the kind of soup they pick, as higher-calorie, cream-based soups that could actually increase the total calories consumed.
"But make sure to choose wisely, by picking low-calorie, broth-based soups that are about 100 to 150 calories per serving. Be careful of higher-calorie, cream-based soups that could actually increase the total calories consumed," Flood added.
The researchers presented their findings at the Experimental Biology Conference in Washington, DC on May 1.