What Is the Volumetrics Diet?

Volumetrics is not a new diet, but it has stood the test of time. Many people use it to lose weight and keep the pounds off for good. The diet is based on the premise that it’s the volume of food eaten, rather than the number of calories consumed, that leads to weight loss. When we eat more food, we experience a sense of satiety or fullness.

Barbara Rolls, PhD, is a nutrition and obesity researcher at Penn State University. She developed the Volumetrics diet based on her research and coauthored The Ultimate Volumetrics Diet, a book published in 1999. She later wrote a second book, The Volumetrics Eating Plan (first published in 2005), showcasing tips, techniques, and recipes.

On the Volumetrics diet, you eat low-calorie foods that fill you up, which helps you lose weight without feeling like you’re on a diet. The plan is designed so that you don't feel hungry or deprived.

You will also learn about "calorie density" if you follow this plan. The recommended foods on the Volumetrics diet have a low energy or calorie density. This means they promote a sense of fullness without a ton of calories. Foods that you avoid on the Volumetrics diet are energy dense, meaning even if they have a lot of calories, you need to eat more of them to feel full. 

To follow the plan, you will eat low-calorie, high-volume foods that contain either a lot of water or a lot of diet-friendly fiber. Water and fiber both increase the sense of satisfaction or satiety. No food is completely banned on the Volumetrics eating plan. You can enjoy foods that are considered to be calorie-dense, like chocolate, as long as it's a treat and as long as you stay within your daily caloric recommendations.

The authors recommend lifestyle changes that lead to long-term weight management, such as keeping an exercise and food journal and planning ahead for social situations that may throw you a curve ball, such as parties. They also recommend that you get at least 30 minutes of exercise most days of the week. In addition, they suggest you weigh in no more than once a week during the weight-loss phase.

What to Eat 

The Volumetrics diet divides foods into four categories, based on their calorie density:

Category One

These foods are very low-density, and the diet emphasizes eating a lot of them. Category one foods include fruits and vegetables (except starchy ones), nonfat milk, and broth-based soup.

Category Two

You will eat lots of foods from category two as well, in reasonable portions. These low-density foods include grains, legumes, low-fat meats, and starchy fruits and vegetables.

Category Three

This category's medium-density foods are permitted on the Volumetrics plan, but take care to eat them in moderation (small servings). These are foods that are higher in fat, refined carbohydrates and/or sugar: Meat, cheese, French fries, bread, ice cream, and so on.

Category Four

High-density category four foods are eaten only occasionally. They are even higher in fats, carbs, and sugars than the category three foods. These include butter, nuts, oil, crackers, cookies, and candy.

Recommended Timing

Frequent eating is recommended on the Volumetrics diet—three meals and a snack or two, as long as they are following the Volumetrics principles (heavy on category one and two foods).

Resources and Tips

The Volumetrics books help you learn the calorie density of the foods you want to eat, so you can adjust the amounts accordingly. They provide a food density list for hundreds of foods, plus a technique for figuring out the calorie density of any food using the number of calories and serving size.

The books include a formula for you to determine how many calories to eat each day, meal plans for 1600 and 2000 daily calories, and lots of healthy recipes as well.

Modifications

Each meal plan can be modified to your specific caloric needs. The 1600-calorie plan, for example, allows for a 400-calorie breakfast, a 500-calorie lunch, a 500-calorie dinner, and a 200-calorie snack. But you can make adjustments. You can also use guidelines in the book to plan your own meals.

The book also provides a maintenance plan to follow once you have met your goal weight, or after six months have passed. After you’ve maintained your weight for another six months, you can start the weight loss plan over again.

Pros

Nutrition

The Volumetrics plan does not exclude any foods or food groups, but it does emphasize those foods that offer nutrients and fiber without a lot of calories. So it is sensible and will allow you get all the nutrients you need from food.

Efficacy

Research by Rolls and others shows that eating this way can help people lose weight.

Lifestyle Changes

The plan encourages regular, moderate physical activity, which is a definite plus. Many diets ignore exercise altogether, despite the fact that regular activity is a vital part of a lifestyle that leads to long-term health and permanent weight loss. Additional recommendations, such as keeping a food diary, will also help users adjust to a new lifestyle.

The Volumetrics diet has a lot going for it, but no one way of eating is perfect for everyone.

Cons

Time Consuming

Especially when you are new to Volumetrics, it will take time. You will need to analyze your food choices for density, keep track of what you are eating, count calories, and prepare food.

Lack of Online Support

There are a few Volumetrics apps, but none developed by the book's authors. If you want to rely on an app instead of a book to check a food's density and track your meals, you will not be able to do so easily.

The Volumetrics diet is inclusive and balanced, like other diets that encourage lifestyle change and gradual weight loss. It's not a quick fix, but a way of eating that takes some time to learn and adopt.

USDA Recommendations

Food Groups

The food recommendations in the Volumetrics diet are consistent with the eating guidelines promoted by the USDA. The eating plan promotes a healthy, balanced diet of fruits, vegetables, and whole grains and encourages you to limit your intake of saturated fat. 

Calories

The daily calorie intakes suggested for weight loss on the Volumetrics plan (1600 for women, 2000 for men) are also similar to the USDA recommendations. While the book helps you determine a smart calorie range for you, you can also do so using this calculator.

Similar Diets

These diets all allow for some indulgences and treats, while at the same time emphasizing foods that are low in calories but high in nutrition. Here's how they compare:

Volumetrics Diet

• Types of Food: All foods are included on this diet. It's the amount of them that matters. You have the freedom to eat as much of the lowest-density foods as you like. And you can still eat the highest-density foods, but do so sparingly.
• Safety: This diet is very safe.
• Effectiveness: This diet is typically effective as long as it's followed carefully. It is a gradual change, not a fast way to drop 10 pounds.
• Sustainability: This is a lifelong way of eating. Once users have lost the desired amount of weight, they switch to a maintenance plan that helps them keep their weight steady.

80/20 Diet

• Types of Food: As with the Volumetrics diet, no foods are off-limits on the 80/20 diet. Instead, users focus on eating whole foods only for 80 percent of the time. For the remaining 20 percent of their meals (about four per week), they can add in some foods that are higher in fat, calories, or sugar.
• Safety: This diet should also be safe as long as the 20 percent meals are not taken to extremes.
• Effectiveness: This will depend on faithfulness to the 80/20 plan, but many people can lose weight by eating this way.
• Sustainability: This diet is also meant to be a long-term approach. Its flexibility makes it easier to adhere to.

Jenny Craig

• Types of Food: Volumetrics has been incorporated into the Jenny Craig diet. Jenny Craig customers purchase portion- and calorie-controlled meals and snacks, but then supplement them with low-density foods according to the Volumetrics philosophy. In this way, they may feel more full while still losing weight.
• Safety: This diet is safe for most people. It restricts calories, but not to an unhealthy amount.
• Effectiveness: This is a gradual weight-loss plan that can work for many people. There is some clinical evidence that it works about as well or slightly better than other commercial diet plans.
• Sustainability: There is a cost associated with Jenny Craig (membership plus meals), so it not something that can necessarily be done forever. But incorporating Volumetrics teaches a way of eating that could be continued without the Jenny Craig meals.

Weight Watchers

• Types of Food: Again, there are no completely restricted foods on this plan. Instead of looking at food density, people on Weight Watchers track their food based on SmartPoints. The SmartPoints system is set up to encourage people to eat more low-calorie, nutrient-rich foods. These also tend to be low-density foods.
• Safety: This program is safe for most people.
• Effectiveness: If followed carefully, this diet is believed to be effective for many people. It has been around for a long time (although it has adapted over the years).
• Sustainability: While it costs about $20 a month to attend Weight Watchers meetings and/or use the app, the philosophy behind the plan is sustainable for long-term use. And people who maintain their goal weight can become members for free.

A Word From Verywell

When the caloric guidelines and food recommendations set forth in this plan are followed correctly, this diet is both effective and nutritious. It will not bring major results very quickly, but instead leads to safe, gradual weight loss of about one to two pounds a week. That's ideal for long-term success—and you can continue eating this way for the long term, too.