Volumetrics

Written by Katie Cameron, Alicia Racelis, PhD
Medically Reviewed by Christine Mikstas, RD, LD on March 25, 2025
10 min read

The Volumetrics diet was created in 2000 by Barbara Rolls, PhD, a professor of nutritional studies at Pennsylvania State University. The diet has been ranked as one of the best eating plans for many years.

The key idea of Volumetrics centers on feeling full. Rolls says it's about the types and amounts of food you eat — not the number of calories or grams of fat, protein, or carbs. So, the trick is to eat more of the right foods for fewer calories.

In some cases, Rolls claims Volumetrics allows you to eat more, not less, than you do now, while still slimming down.

You won't lose a lot of weight quickly, as it's more of a long-term plan. But if you're trying to keep a healthy weight, improve overall eating habits, or lose a few pounds, Volumetrics might be right for you.

What if you could eat more and still lose weight? Unlike diets that focus on cutting back, the Volumetrics diet helps people find healthy foods. And you can eat more of them and still lose weight. 

The key isn't just how much you eat — it's what you eat. Rolls realizes that most people eat the same amount of food every day. The diet plan can help you eat the same amount of food but with lower-calorie options. These may keep you fuller for longer periods, while consuming fewer calories.

Although there are no off-limit foods on this plan, Rolls encourages you to limit calorie-dense foods, such as fast food, oils, and fats. fast food, oils, or fats. Instead, try more water-dense foods such as fruits, vegetables, and soups. That's because water is heavy in volume but calorie-free.

You'll also work toward your weight loss goals. You'll set daily goals for calorie intake and exercise.

Bottom line: The Volumetrics diet can help you lose weight by feeling full on fewer calories.

But remember that everyone's body is different. A diet that works for some may not work for others. WebMD does not back the claims made by the Volumetrics diet. Always talk with your health care provider before making any diet or exercise changes.

If you're interested in the Volumetrics plan, start by talking to your doctor to make sure this new diet is the right choice for you.

Once you're cleared to follow it, start your research. You may want to pick up one of Rolls' books to learn more about sticking to the Volumetrics diet. It may also have recipes you can try out. There are plenty of Volumetrics online websites and community groups you can follow, too.

If you don't cook often, consider checking out some plant-based cookbooks at your local library or searching online for recipes. Start with simple ones that align with the Volumetrics diet. That way, you'll get used to planning ahead, shopping for food, and cooking your meals. 

Once it's part of your routine, consider trying out more complex recipes. If you have a really busy schedule, cook larger meals. You can freeze them to eat for later.

No foods are off-limits on the Volumetrics diet. But every food gets a "score" based on its caloric density. You can find calculators online to help measure your food's caloric density. 

There are four categories, the first being the least dense in calories, while the fourth category has the most calorie-dense foods. The Volumetric diet suggests making most of your meals from category 1 and 2 foods. These lower-calorie foods help keep your plate and belly full for longer periods.

Volumetrics food list

Category 1 foods (caloric density less than 0.6)

Use these low-calorie foods to bulk up your meals when you're on the Volumetrics diet.

  • Brothy soups
  • Fruits such as bananas, apples, and grapefruit
  • Nonfat dairy products, including unsweetened yogurt and skim milk (or unsweetened nondairy replacements)
  • Nonstarchy vegetables, including zucchini, broccoli, kale, and beets

Category 2 foods (caloric density 0.7 to 1.5)

The diet plan suggests eating these foods in moderation. This category includes:

  • Lean cuts of beef and pork, and skinless turkey or chicken
  • Starchy vegetables, such as potatoes or corn
  • Whole grains, such as quinoa and whole wheat pasta
  • Legumes such as beans, chickpeas, or lentils

Category 3 foods (caloric density 1.6 to 3.9)

Eat category 3 foods in smaller portions. They include:

  • Refined carbohydrates, such as pasta, flour tortillas, or white rice
  • Ice cream, cheese, and whole milk
  • Skin-on chicken and turkey, other fatty fish, and meats

Category 4 foods (caloric density 4 to 9)

This category includes fatty or highly processed foods. Eat these foods sparingly.

  • Fast food
  • Nuts and seeds
  • Candy and chips
  • Butter, oil, and shortening

Alcohol is allowed in moderation. But keep in mind it's high in calories and doesn’t satisfy hunger.

Everyone is unique; you may like certain foods but not others. The Volumetrics diet plan aims to help you sustain lifelong health. Unlike many fad diets, you're allowed to still enjoy the foods you love — in moderation. You don't have to limit any major food groups. And since you're not maintaining a dangerous calorie deficit, it's safe in the long term.

Pros of Volumetrics

There aren't extra costs to this diet beyond your normal grocery bill. You don't need to pay for any special classes of food or buy specific products to follow the Volumetrics plan. You can follow this diet on your own. You can join online groups for recipe ideas or communal support, if you're interested.

This diet also adds exercise directly into the plan. You’ll use a pedometer to add 150 steps a day to your routine. Your first goal is to reach an extra 1,000 steps by the end of the week. Ultimately, your goal is to log 10,000 steps a day.

Cons of Volumetrics

A minor downside? You're going to be cooking a lot. It can be hard to eat out on the Volumetrics diet. So, you'll need to prepare most of your meals at home. You might get bored or feel like you're missing out on social outings.

One key thing to note is that counting calories is a major part of the plan. If you've struggled with disordered eating or compulsively counted calories, this diet may trigger you. Talk with your doctor before trying it if you think it may be a problem.

Does it allow for dietary restrictions or preferences?

The plan is flexible enough to adjust to most dietary needs. It can work if you're a vegetarian, vegan, keeping kosher, or restricting salt and fat.

While no foods are off-limits, you'll need to keep an eye on some energy-dense foods. For instance, you may swap the calories of a big bowl of soup for one-sixth of a cheeseburger. The choice is up to you. Would you prefer a cheeseburger? And can you stop after just a few bites if you choose it?

If you follow the recipes, it takes time to calculate energy density and prepare your meals.

Curious about the Volumetrics diet? Read more about why registered dietitian nutritionist Kathleen Zelman, MPH, RD, LD, recommends it. 

Does Volumetrics work?

Absolutely. The advice boils down to a nutritious and sensible diet that any nutritionist would recommend: Cut calories and unhealthy fat, and focus on high-fiber vegetables and fruits.

Zelman notes that Rolls has excellent credentials. She's a professor of nutrition and director of the Laboratory for the Study of Human Ingestive Behavior at Pennsylvania State University. She has also written more than 200 research articles. Volumetrics is largely based on the work done in her lab. And it's backed with solid scientific evidence.

This plan is more of a lifestyle change. It may also help you make wiser food choices and can lead to sustainable and long-term weight loss.

Is it good for certain conditions?

The Volumetrics plan may easily adapt to most health conditions and support weight loss.

Losing weight is helpful for many conditions, such as diabetes, high blood pressure, heart disease, sleep apnea, arthritis, and more. Weight loss may even lower your need for certain medications . But Zelman suggests talking with your doctor before you make any changes.

The final word

Enjoying a diet based on foods naturally high in water with lower energy density is a great way to satisfy hunger . And you may also feel full on fewer calories. The Volumetrics plan can teach you how to make better food choices and cut calories without taking away food groups.

According to Zelman, this plan is ideal for anyone who wants a healthier but flexible diet. There's even advice for people who rely on fast food or eating out. It's also great if you like to cook. It has recipes to help you prepare delicious foods in line with your weight loss goals.

Who shouldn't try Volumetrics?

Calorie counting is a large component of the Volumetrics diet plan. So, if you struggle with disordered eating, this diet may not be right for you. Calorie counting may trigger obsessive thoughts about food. Talk with your doctor before trying the Volumetrics plan.

The higher amounts of fruits and vegetables in the Volumetrics diet may upset your stomach. If you have any form of irritable bowel disease (IBD) or IBS, talk to your doctor first. You may be able to combine Volumetrics with an IBD-friendly diet, such as a low-FODMAP plan that limits foods that irritate your stomach.

Remember, if you're pregnant, immunocompromised, or have any other condition where it's unsafe to lose weight, ask your doctor first. It may be best to say no to the Volumetrics diet for now.

It can be tricky to go out to eat on the Volumetrics plan. Most of the time, you'll be cooking meals from scratch. If you rely on prepackaged food or don't have time to cook, the diet might not be right for you.

Whether you're vegan, prefer to eat kosher, or have a digestive disorder, you can adjust the Volumetrics diet to your dietary restrictions. When you're making a meal plan, look for plant-based recipes or broth-based soups. An average day on the plan might look like this:

Breakfast

  • Oatmeal made with skim milk, topped with apple slices or blueberries
  • Coffee
  • Half a banana

Lunch

  • Chicken tortilla soup with baked tortilla chips
  • Almonds
  • Green salad with low-fat dressing

Snack

  • Hummus with carrots, celery, and tomatoes 
  • Fresh fruit

Dinner

  • Baby spinach salad with sliced chicken breast and tomatoes
  • Wild rice
  • Broccoli and cauliflower
  • Strawberries and Greek yogurt

The best thing about the Volumetrics diet is its flexibility. Since no foods are off-limits, you can usually fit in the foods you want to have in moderation. The key is to fill the bulk of your plate with water-dense, low-calorie foods, or items the plan labels as "Category 1" foods. 

Look for brothy soups or dishes loaded with fruits and vegetables. Still feeling stuck? Try out the following recipes:

Shakshuka with tomatoes and zucchini

Chop up two small zucchini, two cloves of garlic, and one bunch of green onions. Heat a small frying pan and add three tablespoons of olive oil. Then, add your chopped ingredients to your pan with one teaspoon of cumin. Sauté, stirring occasionally, for five to six minutes over medium heat.

Next, add a 15-ounce can of diced tomatoes and a pinch of cayenne pepper to the pan. Then, season the mixture to taste with salt and pepper. Cook for six to seven minutes over medium heat.

Make four hollows in the mixture, then crack an egg into each spot. Cover the pan with a lid and cook for 15-20 minutes until the eggs are set. Top with parsley and/or crumbled feta cheese.

Cannellini bean soup

Chop up one onion and two cloves of garlic. Add them to a large heavy pot with one teaspoon of olive oil. Sauté them over medium heat for five minutes, stirring frequently.

Add the following to the pot:

  • Two 15-ounce cans of cannellini beans, drained and rinsed
  • Two 15-ounce cans of diced tomatoes 
  • One cup of water
  • One cup of diced zucchini
  • Half a cup of frozen peas
  • One cup of chopped carrot
  • One teaspoon of dried thyme
  • One tablespoon of chopped fresh parsley
  • Two cups of vegetable broth

Simmer for 10 minutes, then top with a sprinkle of parmesan cheese and serve.

What foods to avoid on a Volumetrics diet?

You don't really avoid any foods on the Volumetrics diet. But you'll limit certain high-calorie foods, such as processed, sugary, or fatty foods. These are called category 4 foods. You may also need to limit certain foods if you have irritable bowel or other gastrointestinal issues.

Is the Volumetrics diet healthy?

Yes. Unlike many crash diets mentioned online, the plan may help you develop sustainable eating habits. The Volumetric diet may also help maintain your long-term health.

How fast can I lose weight on the Volumetrics diet?

The Volumetrics diet won't help you lose weight quickly. Although a meta-analysis of 48 random controlled trials showed an average weight loss of about 21 pounds after six months. But the plan's goal is long-term health. And you may have gradual, instead of rapid, weight loss.

Is oatmeal a high-volume food?

Oatmeal is high in fiber but low in calories — as long as you don't sweeten it too much. It's a good, high-volume breakfast option for the Volumetrics diet.