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What Is the Volumetrics Diet?

It’s all about volume; lose weight by filling up on low-calorie, nutrient-dense foods

Cutting board with fruits.

Nutrition scientist Barbara Rolls, PhD, created the Volumetrics Diet in 2000 based on years of research. The resulting books — four of them, not including updates and translations — have sold hundreds of thousands of copies.

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Most diet trends end up in the dustbin of history within a few years, but Volumetrics seems to be standing the test of time. It’s also gained the respect of many healthcare professionals.

So, what exactly is the Volumetrics diet?

The Volumetrics diet

The basic principle of Volumetrics is that volume matters. The plan establishes a loose ratio: No food is off limits, but you want to eat much larger quantities of certain kinds of foods than others. By filling up on low-calorie, healthy foods, you don’t feel as hungry as you may on other diets.

Dietitian Julia Zumpano, RD, LD, describes Volumetrics as “a very filling diet, mainly plant-based, that encourages you to eat very nutrient-dense, non-starchy vegetables that pack a lot of nutritional benefit.”

The four categories

The Volumetrics diet breaks food down into four categories. To determine which category a food belongs in, you divide the number of calories per serving by its weight in grams. The result is a number between zero and nine.

If you’re attempting to lose weight on the Volumetrics diet, you’re encouraged to eat 1,400 calories a day. The majority of what you eat in a day should be coming from categories one and two, but occasional, small indulges from categories three and four are acceptable.

  1. Category one (calorie density under 0.6): This category of food forms the foundation of your diet. In other words, this is the stuff you fill up on. These foods — due to their high water content — should help you feel full. A few examples of category one foods are:
    • Fruits like bananas, apples and grapefruit.
    • Non-starchy vegetables like broccoli, carrots, beets and Brussels sprouts.
    • Nonfat dairy products like nonfat yogurt or skim milk. (If you aren’t a dairy drinker, never fear: Most unsweetened milk substitutes also fall into this category.)
    • Broth-based soups of all sorts.
  2. Category two (calorie density 0.7 to 1.5): This category contains foods that are healthy when consumed in moderation. A few examples of category two foods are:
    • Skinless chicken and turkey and lean cuts of pork or beef.
    • Legumes: lentils, chickpeas and dried beans.
    • Starchy vegetables: corn, potatoes and squash.
    • Whole grains: brown rice, quinoa and farro.
  3. Category three (calorie density 1.6 to 3.9): This category contains food that, while still fairly healthy, should only be consumed in small portions. A few examples of category three foods are:
    • Fatty meat and fish, as well as skin-on poultry.
    • Full-fat dairy products such as ice cream, cheese and whole milk.
    • Refined carbohydrates like pasta, white bread and white rice.
  4. Category four (calorie density 4 to 9): This category includes processed, sugary and fatty foods, which should be eaten very sparingly. A few examples of category four foods are:
    • Nuts and seeds.
    • Oils, butter and shortening.
    • Fast food, candy and chips.

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In addition to the dietary measures, the Volumetrics diet recommends getting 30 to 60 minutes of exercise per day.

Pros and cons of the Volumetrics diet

When it comes to weight loss and nutrition, one size doesn’t fit all. Zumpano explains that choosing the diet that’s right for you is a personal process.

“It’s affected by the foods you enjoy, and know that you can’t give up, food availability, and how motivated you are to make changes to your eating habits and food choices,” she says.

Here are some commonly stated benefits and drawbacks of the Volumetrics diet:

Pros

  • Promotes long-term healthy eating. The Volumetrics diet is designed to be sustainable and healthy in the long term. It’s sort of a “come for the weight loss, stay for the health benefits” kind of situation.
  • Weight loss is long-term. Short-term diets often cause your weight to yo-yo back and forth. Because the Volumetrics diet is intended to be a permanent lifestyle change, those who follow the plan may lose weight a bit slower, but have a good shot at keeping it off.
  • No foods are “off-limits.” Go ahead and have a small slice of birthday cake. If you’re craving pretzels, have some. While you have to limit the quantity of category four foods you’re eating, nothing is prohibited.
  • Accessible to everybody. Are you vegan? Do you keep kosher? Have you been diagnosed with celiac disease? That’s OK Because there aren’t any hard and fast restrictions in the Volumetrics diet, you can eat — or not eat — according to your needs.
  • It’s safe! Volumetrics isn’t a fad diet. It doesn’t ask you to maintain a dangerously high-calorie deficit, eliminate entire categories of food from your diet or cultivate a negative relationship with food. You don’t have to cook separate meals for yourself and your children because you aren’t consuming “diet food.” You’re just living a healthy lifestyle.
  • There are lots of resources at your disposal. Besides the four books the diet’s creator already penned, there’s a lot of scientific research supporting the plan, and plenty of websites devoted to recipes.

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Cons

While most doctors and dietitians agree that it’s a solid approach, the Volumetrics diet isn’t perfect. Here are some of the downsides to the program:

  • It limits the consumption of healthy fats. Millennials beware: Volumetrics is coming for your avocado toast! The Volumetrics diet doesn’t distinguish between healthy and unhealthy fats like some other eating plans do. As a result, nuts and seeds occupy the same category (four) as candy and fast food.
  • It may be too calorie-focused. Energy-density calculation is the basis of the Volumetrics diet, which means calorie counting is foundational to the plan. Over time, we’ve learned that calorie counting isn’t foolproof. It can often treat foods that have the same amount of calories — such as 1 ounce of nuts and 1 ounce of chips — as nutritional equivalents. We now know all calories aren’t created equally. As Zumpano puts it, “Even if weight loss is your goal, caloric restriction is not the only way to get towards weight loss.” The good news is, there are ways to deemphasize caloric intake. More on that later.
  • It’s a big-time commitment. The Volumetrics diet isn’t microwave-meal friendly. The emphasis on fresh fruit and vegetables over processed foods makes the diet a healthy choice. But it also makes the plan hard to follow without regular trips to the grocery store and a lot of home cooking. If you decide to go full-bore on the food journaling and energy-density calculation, that will also take some time.
  • It can get boring. All that soup is eventually going to get a little dull. If your meals are starting to feel a bit predictable you can spice things up — literally — by adding new recipes into your rotation.
  • Eating out is difficult. While many chain restaurants can make nutrition information available to you on request, the chef isn’t likely to hand over the recipe. Without that information, categorizing and documenting what you eat outside of your home is going to be challenging.

Making Volumetrics work for you

As with any diet, the key to success on the Volumetrics diet is following the plan in good faith and adjusting it where necessary to fit your lifestyle.

What do we mean by good faith? Zumpano puts it best, explaining, “We are in a hacking world, and it’s OK to hack your diet once in a while. But if you do it on a regular basis, you’re not going to reap the benefits as intended.”

Think about it as embracing the spirit of the diet, not the letter of it. Yes, nuts and fast food are in the same category, but we all know that a handful of almonds is a better choice than a handful of pretzels. Unlike plans that integrate a peer-support system of some kind, you’re only accountable to yourself on the Volumetrics diet.

While the freedom that comes with the Volumetrics diet may tempt some people to try and game the system, it also makes it adaptable to your needs. That, in turn, makes it sustainable.

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How do you adjust the Volumetrics diet to fit your goals and lifestyle? Here are a few examples:

  • Let’s say you’re trying to get healthy, but don’t actually need to lose weight. You could adjust the number of calories you’re taking in each day, while maintaining the ratios prescribed in the diet. You could also ignore calories altogether and focus exclusively on nutrition.
  • Let’s say you do want to lose weight, but calorie counting puts you in a less-than-healthy head space. Don’t do it! Try recording the number of foods you eat from each of the four categories instead, or make a healthy-eating checklist for yourself.
  • Let’s say you can’t exercise for 30 minutes a day. Then do what you can! Five minutes of stretching or taking the stairs instead of the elevator is 100% better than doing nothing. Set realistic and attainable goals that fit your current health and fitness level. Once you crush it, you can set your sights higher.

Is the Volumetrics diet right for you?

Like all diet plans, your mileage may vary when it comes to Volumetrics. If you’re trying to decide whether or not to adopt this approach to eating, the following questions may prove helpful:

  • Are you looking for a quick fix or a lifestyle change? The Volumetrics plan is about long-term healthy eating, not short-term weight loss. If you just need to drop a couple of extra pounds, this probably isn’t the best choice.
  • Are you a decent cook? Do you consider assembling a salad cooking? Does the fire alarm serve as the soundtrack for your culinary adventures? Or is a food delivery service your most-used app? If your answer to any of these questions is “yes,” you may want to opt for a less cooking-intensive diet.
  • Where do you live and what’s your budget? On the one hand, the Volumetrics diet doesn’t require you to purchase branded specialty foods, which can be prohibitively expensive. On the other hand, not all people have equal access to good quality fruits and vegetables, and inflation has made healthy food even less accessible than it used to be. Look carefully at what you’re spending your grocery budget on right now, and see where you can make healthy substitutions.
  • Do you have any gastrointestinal issues? If you have a digestive disorder like irritable bowel syndrome (IBS), you may find that certain otherwise-healthy foods exacerbate your symptoms. You can still follow the Volumetrics diet, but opt for low-FODMAP foods, which are less likely to trigger a flare. Your tummy will thank you.

Some diets, like the DASH diet or the diabetes diet, are designed to address specific health concerns. The Volumetrics diet isn’t, so you’re unlikely to hear about it from your physician unless you ask about it specifically. Before making any radical nutritional changes, do some additional research, and have a conversation with a doctor or dietitian.

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