Volumetrics: eat a bigger plate, eat fewer calories. Annoyingly, it works.
Your stomach counts volume, not calories. Fill it with water-rich food first and you eat less of everything else. No banned foods, no app, just a lot of soup.
The short version
- What it is
- Choosing foods with few calories per bite (low energy density), so you can eat a normal amount of food and still eat fewer calories.
- Good for
- Feeling full while losing weight. Getting more vegetables, fruit and soup into your life.
- Bad at
- Protein, if you're not careful. And fat isn't the enemy it thinks it is.
- Evidence
- Moderate. Strong lab studies, a few good long trials.
- Our take
- One of the best tricks on this whole site. We use it on every plate.
What volumetrics actually is
Volumetrics was developed by Barbara Rolls, a nutrition researcher at Penn State, who turned decades of her own lab studies into a book.6 The key idea is energy density: how many calories a food packs per gram.
Cucumber has hardly any. Crisps have a lot. Soup, salad, fruit, vegetables, lean fish, beans and cooked grains sit at the low end because they're full of water and fibre. Oil, nuts, cheese, biscuits and chocolate sit at the top. Volumetrics doesn't ban the high end. It tells you to build your meals mostly from the low end so the plate is big and the calories are not.
How it works in your body
People tend to eat a fairly consistent weight of food from day to day, not a consistent number of calories.1 Your stomach notices stretch and volume. It has no idea how many calories are in there. So if you lower the energy density of what you eat, you naturally eat fewer calories without feeling like you've eaten less.
Water in food counts. Water in a glass next to food mostly doesn't: it leaves the stomach too fast. That's why soup fills you up and a glass of water with crackers doesn't.
In practice, a volumetrics plate looks like this: half vegetables or salad, a quarter protein (fish, chicken, eggs, tofu or beans), a quarter cooked wholegrains or potatoes, and a spoon of olive oil or a few nuts on top. Pasta gets bulked up with twice the vegetables and half the pasta. Chilli gets more beans and tomatoes, less mince. Porridge gets made with more water and topped with berries. Same dishes you already eat, just "watered down" in the best sense.
The fun part: you're allowed seconds of the low-density stuff. Another bowl of soup? Fine. More salad? Go on. The rules only tighten at the dense end of the list.
What you eat, what you don't
Eat
- Vegetable soups and broths, especially as a starter
- Big salads with a light dressing
- Vegetables: cooked, raw, roasted, all of them
- Fruit, whole
- Beans, lentils, fish, chicken, eggs, tofu
- Cooked wholegrains, porridge
Forget it
- Crisps, biscuits, crackers
- Fried food and pastries
- Sweets and chocolate bars
- Dried fruit by the handful
- Creamy dressings poured on the "healthy" salad
- Soft drinks and juice (lots of calories, no fullness)
Alcohol on volumetrics
OK, now and then
- A spritzer: dry wine with plenty of soda water
- A spirit with soda water and lime, long glass
- One glass of dry wine with food
- A light beer
Calories with no fullness
- Cocktails, cream liqueurs, sweet wine
- Several beers in a row
- Anything mixed with juice, cola or tonic
- Drinking before a meal (you'll eat more)
50 Club: one spritzer, long and cold, with dinner.
Alcohol is the opposite of volumetrics: lots of energy, no fullness at all. All the details are in our alcohol guide.
What it's good for, with proof
Salad first, smaller meal
In a lab study, 42 women ate a compulsory salad before a pasta lunch. A large, low-calorie salad cut total meal intake by 12%. The same salad loaded with cheese and creamy dressing raised it by 17%.2 Same salad, different dressing, opposite result.
Soup first, too
Sixty adults ate a bowl of vegetable soup before lunch. On soup days they ate about 20% fewer calories in total at that meal. It didn't matter whether the soup was chunky or blended.3
Weight loss without counting
In a year-long trial, 97 women with obesity were told to cut fat. Half were also told to eat a lot more water-rich food, especially fruit and vegetables. Nobody got a calorie target. The fruit-and-veg group lost 7.9 kg against 6.4 kg, ate a greater weight of food, and reported less hunger.4 More food, less hunger, more weight lost. That's the whole sales pitch, and it held up.
The uncomfortable truth
"Low calorie density means low fat." Volumetrics grew up in the low-fat era, and the original book shows it. Olive oil, nuts and oily fish are calorie-dense and still some of the healthiest foods you can eat. The trick is the amount, not avoiding them.
"Diet food is low density, so it's fine." Plenty of light yoghurts, puffed snacks and low-fat ready meals are low density and still ultra-processed. In a controlled trial, people ate about 500 kcal a day more on ultra-processed food than on unprocessed food, even when the meals offered were matched for energy density.5 Volume helps. Real food helps more.
The risks
- Too little protein. A plate of salad and soup can be very low in protein. Add fish, eggs, beans or chicken, or you'll be hungry by 4 pm and lose muscle.
- Too little fat. Some vitamins (A, D, E, K) need fat to be absorbed. A tablespoon of olive oil on the salad is your friend.
- Bloating. Lots of fibre all at once can mean gas and cramps. Build up slowly and drink water.
- Not enough for some people. Older adults, people with small appetites, and athletes may struggle to get enough energy from bulky food.
Allergies: watch the staples
| Staple | Allergen (EU list of 14)7 | Swap |
|---|---|---|
| Ready-made soups and stock cubes | Celery, often cereals containing gluten or milk | Homemade broth without celery; check labels |
| Salad dressings, mayonnaise | Mustard, eggs | Olive oil and lemon |
| Fish, prawns | Fish, crustaceans | Chicken, eggs, beans |
| Wholegrain pasta, couscous, bread | Cereals containing gluten | Brown rice, quinoa, potatoes |
| Low-fat yoghurt | Milk | Soy yoghurt |
| Sesame dressing on the salad | Sesame | Sunflower seeds |
Don't do volumetrics if you…
- are underweight or struggle to eat enough
- have ever had an eating disorder (filling up to avoid eating is a known pattern)
- have an inflammatory bowel disease flare, or have been told to eat low-fibre
- have kidney disease and limits on potassium or fluid
- are on a texture-modified diet for swallowing problems
Healthen me asks about all of these and gives you a different plan if any apply.
How we use volumetrics in your plan
This is a building block, and it's in almost every plan. Your meals come with big vegetable portions as standard, and lunch or dinner often starts with soup or a salad.
We fix the two weak spots: every plate still gets a proper protein portion, and healthy fats like olive oil stay. Our engine does the calorie counting in the background, so the big plate fits your target without you weighing a thing.
This article is general information, not medical advice. If you have a medical condition or take medication, talk to your doctor before changing how you eat.
Sources
- Rolls BJ. The relationship between dietary energy density and energy intake. Physiology & Behavior 2009;97(5):609–615. doi.org/10.1016/j.physbeh.2009.03.011
- Rolls BJ, Roe LS, Meengs JS. Salad and satiety: energy density and portion size of a first-course salad affect energy intake at lunch. Journal of the American Dietetic Association 2004;104(10):1570–1576. doi.org/10.1016/j.jada.2004.07.001
- Flood JE, Rolls BJ. Soup preloads in a variety of forms reduce meal energy intake. Appetite 2007;49(3):626–634. doi.org/10.1016/j.appet.2007.04.002
- Ello-Martin JA et al. Dietary energy density in the treatment of obesity: a year-long trial comparing 2 weight-loss diets. American Journal of Clinical Nutrition 2007;85(6):1465–1477. doi.org/10.1093/ajcn/85.6.1465
- Hall KD et al. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell Metabolism 2019;30(1):67–77. doi.org/10.1016/j.cmet.2019.05.008
- Rolls BJ. The Volumetrics Eating Plan. New York: HarperCollins, 2005.
- Regulation (EU) No 1169/2011 on food information to consumers, Annex II (the 14 allergens). eur-lex.europa.eu/eli/reg/2011/1169/oj