What Is the Volumetrics Diet? Foods, Rules, Risks & Alternatives

The volumetrics diet sorts foods by energy density: the calories in a serving divided by its weight in grams. Barbara Rolls, a professor of nutritional sciences at Penn State, developed the approach and the books that teach it: The Volumetrics Weight-Control Plan (with Robert Barnett, 2000), The Volumetrics Eating Plan (2005), and The Ultimate Volumetrics Diet (2012). People often eat a similar weight of food from meal to meal. When that weight comes from foods with more water and fiber, the portion can carry fewer calories.

Vegetables, fruit, grains, beans, dairy, fish, meat, nuts, and oils all stay available. Portions tighten as calories per gram rise. Social-media “volume eating” — a huge bowl of raw vegetables and little else — is narrower than the book pattern, which still includes protein, starch, and fat.

Disclaimer

Educational only. Not medical advice, and not a weight-loss plan for you. Consult a qualified clinician or a registered dietitian nutritionist before you change how you eat, especially if you have a medical condition, take medications, are pregnant or breastfeeding, are underweight, or have a history of disordered eating.

Quick facts

What it is	A lifestyle pattern that uses calories per gram to steer portions, from Barbara Rolls’s research and books.
Core idea	Build most of the plate from water-rich foods so a satisfying portion can carry fewer calories.
Risk band	Lifestyle. Risk rises when “eat freely” becomes a rigid rule, when volume crowds out enough energy, or when a limit on volume, fiber, sodium, or potassium is ignored.
What it is not	A low-carbohydrate diet, a cleanse, a supplement, or a promise of a set weight change.
Closer siblings	Balanced plate, Mediterranean, DASH

How it works

Energy density runs from about 0 to 9 calories per gram. Water adds weight and no calories. Fat is about 9 calories per gram. Carbohydrate and protein sit near 4. A broth-and-vegetable soup and a cream soup can fill the same bowl and differ sharply in calories.

The 2012 book sorts foods into four bands. Rolls’s 2017 review in Nutrition Bulletin reprints them. Sauces and frying move a food between bands.

Band	Calories per gram	How the books frame it	Examples from that chart
1. Very low	Under 0.6	Lean on these when hungry	Most fruit, non-starchy vegetables, broth-based soups
2. Low	0.6–1.5	Reasonable portions	Whole grains, lean proteins, legumes, low-fat dairy
3. Medium	1.6–3.9	Manage portions	Breads, cheeses, higher-fat meats, many desserts
4. High	4.0–9.0	Small portions, less often	Fried snacks, candy, cookies, nuts, oils, butter

Meals start in bands 1 and 2. Bread, cheese, oil, and dessert come from bands 3 and 4 in smaller amounts. This page does not assign a calorie target, a gram target, or a weekly rate of loss.

A habit the books and the meal studies share is a low-density first course: broth-based soup, a salad in a light dressing, or a piece of fruit. In laboratory meals, that course reduced what people ate next, when the first course was low in calories and the rest of the meal was portioned. A large salad followed by unlimited fried food does not inherit that finding.

In one laboratory comparison, water cooked into soup or stew reduced later intake more than the same water drunk beside a drier dish. Drinking water still matters for hydration. The books also mention activity. This page does not set minutes or steps.

Foods and rules

These lists describe the pattern as taught. They are not a medical order.

Most of the plate

• Non-starchy vegetables: greens, tomatoes, peppers, broccoli, carrots, mushrooms
• Whole fruit more often than juice
• Broth-based soups and vegetable-bean stews
• Whole grains such as oats, barley, and brown rice, in a portion that fits the plate
• Beans, lentils, and peas
• Fish, skinless poultry, eggs, and tofu, grilled, baked, or poached rather than breaded and fried
• Low-fat milk or unsweetened yogurt, if dairy sits well

Smaller amounts

• Bread, crackers, cheese, and higher-fat meats
• Avocado and dried fruit, nutritious and more concentrated than raw vegetables or fresh fruit
• Olive oil, butter, nuts, seeds, and nut butters
• Chips, cookies, candy, and deep-fried snacks

Let water-rich foods supply most of the meal’s weight, and use fat as a flavoring. A teaspoon of oil on vegetables is a different meal from the same vegetable deep-fried. Keep a protein food on the plate. Greens are very low density; cheese, croutons, fried toppings, and creamy dressing can make a salad high density. Juice and dried fruit fit as portioned foods, not as stand-ins for a bowl of berries.

A sample day, as a sketch only

• Breakfast: oatmeal with berries and a spoon of yogurt.
• Lunch: broth-based vegetable and bean soup, and a lightly dressed salad.
• Snack: an apple, or carrots with a small spoon of hummus.
• Dinner: baked fish or tofu, a large serving of vegetables, a modest scoop of rice or potato, and a little oil or a few nuts.

The balanced plate draws the same kind of meal without the arithmetic. Dal with vegetables, fish with greens, or a vegetable-heavy soup can fit, including frozen produce and rinsed canned beans.

Evidence snapshot

Rolls’s 2017 review in Nutrition Bulletin summarizes the main line of this research. In controlled meals, holding calories per gram steady while changing the share of fat often left calories eaten similar. Lowering calories per gram, with fat held steady, tended to lower calories eaten, because the weight of food stayed relatively steady. Those are lab and short-diet findings. They are not a forecast for your week.

The same review describes longer trials in which more vegetables and fruit, and less fat, lined up with a lower energy density and with greater weight loss than fat advice alone. It also says more long-term evidence is needed, including whether hunger later offsets the pattern. An association in a review is not your result. Adding vegetables is a different diet from diet drinks and dry diet products. This page does not quote pounds or a timeline.

Potential benefits

A larger portion of vegetables, fruit, or broth-based soup can feel more satisfying than a small portion of a dry, high-fat food with similar calories. That satiety claim is why the pattern is taught. It does not guarantee a change in hunger, weight, or lab results.

The usual food groups stay on the plate, which is why shopping lists often match the Mediterranean diet and DASH. Adding vegetables to a mixed dish, starting with soup, and keeping nuts as a garnish also sit inside a balanced plate. A careful week does not treat a diagnosis or replace a medicine.

Risks and who should avoid a self-directed plan

Body weight is Your Money or Your Life territory even in a lifestyle band.

“Eat freely” can harden into a rule. Band 1 is food to turn to when you are hungry. Nuts, oils, avocado, and cheese are portioned because they are energy-dense, and they are also how many meals stay satisfying. Cutting them out to chase a lower number is a stricter diet than the books describe.

Volume can hide too little energy. A plate of mostly watery vegetables can feel full and still fall short on calories, protein, and fat. That is a poor match for children and adolescents, pregnancy and breastfeeding, people who are underweight, older adults with a small appetite, athletes with high needs, and anyone rebuilding after illness.

Some bodies cannot take a large volume. Gastroparesis, stomach or bariatric surgery, significant reflux, and some inflammatory bowel flares limit how much food the stomach can hold. A big-bowl plan can worsen pain, reflux, dumping, or blockage risk. The clinician who knows that history sets the volume. A sudden jump in beans and raw vegetables also causes bloating. For irritable bowel syndrome, a low-FODMAP trial is a separate clinical tool, covered in the low-FODMAP entry, and it belongs with a dietitian.

Sodium and potassium travel with some low-calorie foods. Broth, canned soup, and soy sauce can be light in calories and heavy in salt. Heart failure, a fluid limit, and blood-pressure care can make that unsafe. When sodium is the clinical issue, DASH is the closer public pattern, and a prescribed limit still outranks either article. Very large produce intakes raise potassium. In advanced kidney disease, the renal diet takes priority.

Tracking can become the diet. If dividing calories by grams decides whether you may eat, talk with a clinician who understands eating disorders. Packaged challenges and promises of a fixed weekly loss are marketing. Energy balance, as education, is covered in calorie deficit. That page is not a deficit for you to copy.

Who should talk with a clinician first

Speak with a clinician or registered dietitian nutritionist first if you are pregnant, postpartum, breastfeeding, or feeding a child; if you are underweight or losing weight without meaning to; if you have an eating disorder or rigid food rules; if you have had stomach surgery, gastroparesis, or trouble swallowing; if you have kidney disease, heart failure, or a sodium, fluid, or potassium limit; if you use insulin or similar medicines; or if you already follow a prescribed diet.

Bring a few days of meals and your medicine list. Chest pain, trouble breathing, fainting, vomiting that will not stop, or a sudden inability to keep food down are emergencies.

Safer alternatives

The balanced plate puts vegetables and fruit on about half the plate and splits the rest between protein and grains, with enough fat that the meal is worth eating. It does not require a calories-per-gram sum.

The Mediterranean diet leans on vegetables, legumes, whole grains, olive oil, and fish. Olive oil and nuts sit in the high-density band, so the two patterns will not match gram for gram. Plants come first in both.

The DASH diet overlaps on produce, beans, whole grains, and lean proteins, and it is taught with blood pressure and sodium in mind. A soup-heavy week is not a stand-in for a sodium limit you were given.

If you already follow a prescribed pattern — renal, carbohydrate-counted, gluten-free for celiac disease, or texture-modified after surgery — that plan stays in charge.

FAQ

What is the volumetrics diet?

A way of building meals so a satisfying weight of food carries fewer calories. You lean on vegetables, fruit, and broth-based soups, and you keep oils, nuts, cheese, and fried or sugary foods in smaller portions. The four bands come from Barbara Rolls’s books.

What do you eat, and what is limited?

Most meals are vegetables, fruit, whole grains, beans, and lean proteins, plus low-fat dairy if you tolerate it. Bread, cheese, oils, nuts, and sweets stay in smaller amounts. Grilled fish with a large serving of vegetables is a lower-density meal than the same fish breaded and fried.

Is it low carb?

No. Fruit, grains, beans, and starchy vegetables are part of the pattern. If you take diabetes medicine that can cause low blood glucose, ask a clinician how a larger produce intake fits your targets. This page does not set gram goals.

Does it cause weight loss?

Laboratory meals have found lower calorie intake when calories per gram fall and the weight of food stays similar. Some longer trials report weight loss with that coaching. Hunger, medicines, sleep, and activity change the outcome. Only your own trend, reviewed with a clinician, describes your result.

How does it compare with Mediterranean and DASH?

All three are plant-forward lifestyle patterns. Volumetrics centers on calories per gram. Mediterranean descriptions give olive oil, nuts, and fish a larger role. DASH pays more attention to sodium. The balanced plate is one meal without a density chart.

Are nuts and olive oil allowed?

Yes, in small portions. Both are high in calories per gram, and both are foods many traditional patterns keep. A sprinkle of nuts on vegetables matches the teaching. A ban on them is a different diet.

Related

• Balanced plate — the same direction, drawn as one plate
• Mediterranean diet — plant-forward sibling, with olive oil and fish in a larger role
• DASH diet — plant-forward sibling taught with sodium in mind
• Diets directory — A–Z encyclopedia hub

Sources

• Rolls BJ. Dietary energy density: applying behavioural science to weight management. Nutrition Bulletin. 2017;42(3):246–253. Reprints the four bands from the 2012 book and summarizes the studies above.
• Rolls B, Barnett RA. The Volumetrics Weight-Control Plan. 2000.
• Rolls B. The Volumetrics Eating Plan. 2005.
• Rolls B. The Ultimate Volumetrics Diet. 2012.

Disclaimer

Educational only. Not medical advice, and not a promise of weight change. Consult a qualified clinician or registered dietitian nutritionist before you change your diet.

Last reviewed

2026-09-24. Draft for editorial review. Not published.