Public Release: 

Reduce calories, stave off hunger with water-rich foods -- not water

Penn State

University Park, Pa. --- Drinking water before or with your meals is a healthy habit, but Penn State research has shown that it won't satisfy your hunger or help you eat less to control your weight.

Dr. Barbara Rolls, who holds Penn State's Guthrie Chair in Nutrition, says "We're not sure where the idea that drinking water before or during a meal can stave off hunger originated but it was very popular in the 60s, and is still a common belief. Our research shows that, although drinking water with meals may not be an effective method for reducing calories, eating water-rich foods can lower calorie intake."

Rolls and her research team have shown that eating foods with a high water content - pasta dishes with additional vegetables, smoothies, soup, fruits and vegetables -- can offer a way to cut back on calories and still feel full and satisfied.

The study of the effects of water on food intake is detailed in the October issue of the American Journal of Clinical Nutrition in a paper, "Water Incorporated Into A Food But Not Served With A Food Decreases Energy Intake In Lean Women." The authors are Rolls, Elizabeth Bell, doctoral candidate in nutrition, and Michelle Thorwart, project associate.

The study was the first to systematically examine the effects of water served as a beverage and water incorporated into a food on subsequent food intakes. The 24 lean women who participated in the study ate breakfast, lunch and dinner one day a week in Penn State's Laboratory for the Study of Human Ingestive Behavior for four weeks. They were served a first course 17 minutes before lunch that consisted of either a chicken rice casserole, the same casserole with a glass of water, or a bowl of chicken rice soup. Even though the soup and the casserole-served-with-water contained exactly the same ingredients in the same amounts, the soup was more effective in curbing appetite and reducing the calories the women consumed during lunch.

"The body processes hunger and thirst through different mechanisms. Clearly, if a beverage is processed by thirst, it will not reduce hunger, " Rolls says.

Rolls, a faculty member in Penn State's College of Health and Human Development, notes that soup is not the only water-rich food that can help decrease calorie intake. She says that previous research by her group has shown that by consuming other water-rich foods, too, dieters can eat their typical size serving of food, reduce calorie intake and still be satisfied. In other words, dieters don't have to limit portion size as much if they eat foods that are high in water content.

For example, pasta salad bulked up with zucchini, carrots and other veggies, which have a high water content, can provide a portion double the size for the same calories as a salad made without the veggies. Chili augmented with lots of veggies and beans can expand the serving size of that dish while still maintaining a low calorie count. Sprouts, lettuce and tomato can round out the satisfaction that a sandwich provides without increasing calories.

Rolls explains that her group's research has shown that feeling full depends on eating a satisfying amount of food. Tiny portions just don't do it no matter how much water you drink on the side. The energy density of food, or the ratio of calories to the weight of food, is what matters. Foods with a high energy density have lots of calories in a small serving and are typically lower in water content. For example, a 100-calorie serving of raisins, a high energy density food, contains only one quarter cup. A 100-calorie serving of grapes, a low energy density, high - water content food, contains one and two thirds cups.

Rolls's new book, "Volumetrics, Feel Full on Fewer Calories," to be published in December by Harper Collins, will provide more information on the energy density of specific foods. The book will also detail her energy density-based eating plan and offer menus, recipes and tips for modifying your favorite dishes.

As far as her current study of water is concerned, however, Rolls notes that she doesn't want to discourage people from drinking water either before, during or after their meals.

"Water is critical and many people, especially the elderly, don't drink enough," she says. "However, by following the Volumetrics eating plan, "you'll consume more water in the form of water-rich foods such as fruits, vegetables and soup. The additional water available from the foods is another positive health benefit provided by this eating plan."


EDITORS: Dr. Rolls is at (814) 863-8482 or at by email.

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