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Research and general acceptance



Volumetrics is a weight-management plan that encourages dieters to control calories while eating enough food to feel satisfied. People who eat according to the Volumetrics plan focus on eating water- and fiber-rich foods to achieve satiety, the feeling of fullness after a meal.


Volumetrics is based on more than two decades of research by nutritionist Barbara Rolls, Ph.D., the endowed Guthrie Chair in Nutrition at Pennsylvania State University. Rolls has been president of the Society for the Study of Ingestive Behavior and the North American Association for the Study of Obesity. She was also a member of the Advisory Council of the National Institute of Diabetes and Digestive and Kidney Diseases (NIH) and a member of the National Task Force on the Prevention and Treatment of Obesity. She has also been published in a variety of peer-reviewed journals, including the Journal of the American Dietetic Association,New England Journal of Medicine, and the American Journal of Clinical Nutrition.

In her laboratory at Penn State, Rolls has studied dietary patterns and eating behavior. Based on her research and that of others, she has determined that the volume of food that people eat affects both how satisfied they feel and how much they eat.

Scientists like Rolls who study eating behavior have observed that over the course of a day or two, a person eats about the same weight of food. To lose weight, then, a person can lower the calories in each portion of food while maintaining the same amount of food. If a dieter eats the Volumetrics way and increases the water and fiber content in their daily food intake, he or she will still feel full. However, because the person is taking in fewer calories than before, weight loss will occur.


According to Volumetrics, the ideal weight-loss program has several elements.

  • It satisfies hunger.
  • It reduces calories.
  • It meets a person's nutritional needs.
  • It includes physical activity.

In addition, a weight-loss plan should also be enjoyable so that users feel able to sustain the healthy eating principles long-term.

Volumetrics offers detailed guidance on nutrient and fluid intake, as well as physical activity. In the 326-page publication Volumetrics: Feel Full on Fewer Calories, published in 2000, the authors make the following weight management recommendations:


Constipation —Inability or difficulty passing stool.

Diverticula —Small pouch in the colon.

Diverticular disorders —Disorders that involve the development of diverticula.

Energy density —The calories in a given portion of food.

Hemorrhoids —Swollen and inflamed veins around the anus or rectum.

Insoluble fiber —Fiber that cannot dissolve in water; found in whole grains, breads, and cereals as well as carrots, cucumbers, zucchini, and tomatoes.

Irritable bowel syndrome —A chronic colon disorder that involves constipation and diarrhea, abdominal pain, and mucus in the stool.

Satiety —The feeling of fullness after a meal.

Soluble fiber —Fiber that partially dissolves in water; found in oatmeal, nuts and seeds, beans, apples, pears, and berries.

  • Calories (Energy): Reduce usual intake by 500 to 1,000 calories per day, depending on weight-loss goals. This practice should lead to a healthy weight loss of 1 to 2 pounds per week.
  • Fat: Limit to 20 to 30% of total calories and look for foods reduced in fat and calories.
  • Carbohydrates: Carbohydrates should comprise 55% or more of total calories; it's preferable to choose carbohydrates from whole grains, vegetables, and fruits because they are more satiating.
  • Fiber: Eat at least 20 to 30 grams per day from whole grains, fiber-rich breakfast cereals, and whole fruits and vegetables, as opposed to fruit juices. Fiber is key for lowering energy (calorie) density as well as increasing overall satiety.
  • Sugar: Choose a diet moderate in added sugars. Rolls suggests lowering intake of sodas and other sugary drinks because these foods add calories without satiety. Use small amounts of sugar to make low-energy, nutritious foods tastier.
  • Protein: About 15% of daily calories, or 0.4 grams per pound of body weight, should come from protein foods. Beans, low-fat fish, poultry without skin, and lean meats are recommended as the most satiating choices. Adequate amounts of protein are needed to prevent muscle loss and maintain metabolism.
  • Alcohol: Consume with meals and limit to one drink per day for women; men should consume no more than two drinks daily.
  • Water: Water consumption is a key component of the Volumetrics eating plan. It recommends women drink at least 9 cups daily, whereas men should consume 12 cups daily. Water can come from foods or beverages and should replace sugary drinks in the diet.

To manage weight, dieters should also get at least 30 minutes of moderate-intensity exercise on most, if not all, days of the week. Resistance training should be included twice a week. Rolls recommends walking at 3 to 4 miles per hour as an ideal choice for most people, even those who have substantial amounts of weight to lose. Dieters should also focus on reducing the overall amount of time they spend in sedentary pursuits, such as television watching, and increase physical activity by gardening, house cleaning, or other non-sedentary activities.

Volumetrics offers specific tips on how dieters can lower the energy (calorie) density of their food intake while maintaining satiety. For example, when choosing a sweet snack, a dieter may opt for grapes over raisins. For 100 calories, a dieter can eat nearly 2 cups of grapes, compared to only 1/4 cup of dried raisins. Choosing the grapes would be a better Volumetrics choice because a person is more likely to feel full longer due to the grapes' increased water content.

Although dieters do not need to change everything about their diets, following the Volumetrics recommendations and eating more meals and snacks lower in energy density will help a person enjoy reasonable food portions while controlling calories, Rolls says.

No foods are forbidden on the Volumetrics plan, but fried foods, sweets, and fatty foods should be limited or avoided. Volumetrics also suggests that people limit“dry” foods, such as crackers, popcorn, and pretzels, since these foods are higher in calories and provide little satiety.

A sample menu on the Volumetrics plan might include:

  • Breakfast: Oatmeal: 1-⅓ cup oatmeal made with water; ½ medium apple;1 teaspoon cinnamon; 2 teaspoons brown sugar; 1 cup nonfat milk; ½ grapefruit; Coffee or tea
  • Lunch: Grilled Chicken Salad: 3 ounces grilled chicken breast; 3 cups chopped Romaine lettuce; 4 slices red bell pepper; 2 tablespoons crumbled blue cheese; 1 tablespoon chopped walnuts; 2 tablespoons light dressing; 1 whole wheat pita bread; 1 cup sliced strawberries
  • Snack: 1 cup Cheerios; ½ cup nonfat milk; 2/3 cup fresh blueberries
  • Dinner: Steak Fajita: 3 ounces grilled sirloin steak; ½ cup green pepper; ½ cup onion; 1 tablespoon reduced sodium soy sauce; 2 tablespoons salsa; ½ cup shredded Romaine lettuce; ½ cup diced fresh tomato; 2 tablespoons nonfat sour cream; 1-10 inch flour tortilla; ½ cup corn; 1 cup diced cantaloupe

In addition to nutritional recommendations, Volumetrics provides lists of very low-energy-dense foods, low-energy-dense foods, medium-energy-dense foods, and high-energy-dense foods to help dieters decide foods to incorporate or avoid in their eating plan. In Volumetrics: Feel Full on Fewer Calories and other publications, Rolls includes sample menu plans based on daily caloric intake, recipes, serving size recommendations, and cooking tips and techniques.

The Volumetrics publications also address the issues of emotional eating and encourage dieters to eat a variety of foods to enhance satiety and pleasure. The authors cite a study at Tufts University in Boston that found that overweight people eat a wide variety of energy-dense foods, but normal-weight people consume a variety of foods that are lower in energy density.

Volumetrics also addresses a variety of dieting myths and common questions, such as:

  • Is skipping meals OK?
  • Will frequent meals help me control hunger?
  • Should I avoid eating after 8 p.m.?
  • Should I eat more slowly?

Volumetrics avoids gimmicks and promises of how much weight readers can lose, maintaining that“We can't guarantee that you'll lose weight and keep it off.” The authors also acknowledge that“changing your eating habits is very difficult” and that“if your overeating is rooted in deep emotional causes, you will need to address these issues, perhaps with a therapist, before you are ready to adopt the eating style.”


People who wish to lose weight or maintain their current weight can use the nutritional principles of Volumetrics to achieve this goal.


In addition to helping people lose weight, Volumetrics may also be beneficial for people with conditions that may aided by eating higher-fiber diets, such


  • What are the potential benefits for a person of my age, sex, and lifestyle in adopting the Volumetrics plan?
  • What are the potential health risks, if any, for me as an individual?
  • Are there any health concerns associated with Volumetrics?
  • Do I need to worry about vitamin, mineral, or nutrient deficiencies if I eat according to the Volumetrics plan?
  • Have you had any patients who have used Volumetrics? What were their results and did they maintain weight loss over the long term?

as hemorrhoids, constipation, irritable bowel syndrome, and diverticular disorders. In addition, high-fiber intake, especially soluble fiber, has been linked to lower blood cholesterol levels. A reduced risk of type 2 diabetes has also been tied to consumption of a high-fiber diet.


Volumetrics encourages dieters to eat foods rich in fiber. However, people who normally eat a low-fiber diet and add too much fiber too quickly can suffer some uncomfortable side effects, including intestinal gas, abdominal bloating, cramping, and constipation.

Increasing fiber gradually to the 20 to 30 grams daily recommended by Volumetrics can help a person's digestive system to adjust to the dietary change. Drinking plenty of water also helps to keep stools soft and bulky and prevent constipation.


There are no risks associated with the dietary recommendations made in the Volumetrics Eating Plan.

Research and general acceptance

The principles of Volumetrics are consistent with the recommendations made by the United States Department of Agriculture and outlined in its Food Guide Pyramid. It is generally accepted by registered dietitians and nutritionists as a sensible, effective, and nutritionally balanced eating plan that promotes healthy food choices based on research and science. Volumetrics: Feel Full on Fewer Calories and other Volumetrics publications include references to a variety of research studies published in peer-reviewed journals.

In 2004, the Tufts University Health and Nutrition Letter named The Volumetrics Eating Plan one of the three best diet books on the market. In addition, the American Dietetic Association includes The Volu-metrics Eating Plan on its 2007 Good Nutrition Reading List.



Rolls, Barbara. The Volumetrics Eating Plan. HarperCollins Publishers, 2005.

Rolls, Barbara, and Barnett, Robert. The Volumetrics Weight-Control Plan: Feel Full on Fewer Calories. HarperTorch Publishers, 2003.

Rolls, Barbara, and Barnett, Robert. Volumetrics: Feel Full on Fewer Calories. HarperCollins Publishers, 2000.

Rolls, Barbara, and Hill, J. Carbohydrates and Weight Management. ILSI Press, 1998.


Flood, J.E., Roe, L.S. and Rolls, B.J. (2006). The effect of increased beverage portion size on energy intake at a meal. Journal of the American Dietetic Association, 106(12): 1984-1990.

Kral, T.V.E., Roe, L.S. and Rolls, B.J. (2004). Combined effects of energy density and portion size on energy intake in women. American Journal of Clinical Nutrition, 79, 962-968.

Rolls, B.J., Morris, E.L. and Roe, L.S. (2002). Portion size of food affects energy intake in normal-weight and overweight men and women. American Journal of Clinical Nutrition, 76, 1207-1213.

Rolls, B.J., Roe, L.S. and Meengs, J.S. (2004). Salad and satiety: energy density and portion size of a first course salad affect energy intake at lunch. Journal of the American Dietetic Association, 104, 1570-1576.


American Dietetic Association. 120 South Riverside Plaza, Suite 2000, Chicago, Illinois 60606-6995. (800) 877-1600. <http://www.eatright.org>

Laboratory for the Study of Human Ingestive Behavior. Pennsylvania State University, 226 Henderson Building, University Park, PA 16802. (814) 863-8482. <http://nutrition.hhdev.psu.edu/foodlab>

USDA Food and Nutrition Information Center. National Agricultural Library, 10301 Baltimore Avenue, Room 105, Beltsville, MD 20705. (301) 504-5414. <http://fnic.nal.usda.gov/>

Volumetrics Eating Plan. <http://www.volumetricseatingplan.com>

Amy L. Sutton