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 Dr. Barbara Rolls, 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 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 determined that the volume of food that people eat affects both how satisfied they feel and how much they eat.

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.
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.
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.


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

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:

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 doing 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:

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:


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 be aided by eating higher-fiber diets, such 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.


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 in its Dietary Guidelines for Americans. It is generally accepted by registered dietitians 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 Academy of Nutrition and Dietetics (formerly the American Dietetic Association) included The Volumetrics Eating Plan on its 2007 “Good Nutrition Reading List.”



Rolls, Barbara. The Volumetrics Eating Plan. New York: Harper, 2007.

Rolls, Barbara, and Robert A. Barnett. The Volumetrics Weight-Control Plan: Feel Full on Fewer Calories. HarperCollins, 2000.

Rolls, Barbara, and Robert A. Barnett. Volumetrics: Feel Full on Fewer Calories. New York: Harper, 1999.

Rolls, Barbara, with Mindy Hermann. The Ultimate Volumetrics Diet: Smart, Simple, Science-Based Strategies for Losing Weight and Keeping It Off. New York: HarperCollins, 2012.

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


Flood, J. E., L. S. Roe, and B. J. Rolls. “The Effect of Increased Beverage Portion Size on Energy Intake at a Meal.” Journal of the American Dietetic Association 106, no. 12 (2006): 1984–90; disc. 1990–91.

Kral, T. V. E., L. S. Roe, and B. J. Rolls. “Combined Effects of Energy Density and Portion Size on Energy Intake in Women.” American Journal of Clinical Nutrition 79, no. 6 (2004): 962–68.

Rolls, B. J., E. L. Morris, and L. S. Roe. “Portion Size of Food Affects Energy Intake in Normal-Weight and Overweight Men and Women.” American Journal of Clinical Nutrition 76, no. 6 (2002): 1207–13.

Rolls, B. J., L. S. Roe, and J. S. Meengs. “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, no. 10 (2004): 1570–76.


“Volumetrics Diet.” U.S. News & World Report: Health. https://health.usnews.com/best-diet/volumetrics-diet (accessed April 23, 2018).

Amy L. Sutton

  This information is not a tool for self-diagnosis or a substitute for professional care.