Articles

Evidence based

Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

Our team of licensed nutritionists and dietitians strive to be objective, unbiased, honest and to present both sides of the argument.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

Diets Debunked: The Volumetrics Diet

Written by Dr. Michael Ruscio, DC on April 26, 2023

Written by Dr. Michael Ruscio, DC on April 26, 2023 — Reviewed by Aimee Gallo

Can You Really Eat More and Weigh Less?

• What is the Volumetrics Diet?|
• Volumetrics and Weight Loss|
• How the Volumetrics Diet Impacts on Health|
• Pros and Cons of Volumetrics|
• Is Volumetrics for You?|
• Making it Work|

Next up in our round-up of popular diets is the Volumetrics diet or the “eat more, lose weight” diet as it is popularly called. I wanted to include this in our series as it’s a diet that can be effective for people who are trying to manage their weight.

Research (detailed below) shows that adopting the principles of the Volumetrics diet can ease cravings, fight hunger, and help weight loss. The diet may also be beneficial for heart health, according to research. But it can also be overly complicated and restrict the intake of good fats too much. If you have digestive or other gut-related issues, you might need to make some adaptations to the diet to make it more suitable.

With Volumetrics, and in fact, all the diets that I’m “debunking” in this series, I’ll rarely come down on the side of an eating plan being either wholly good or wholly bad. What works for one person dietary-wise may not be so good for another, and vice versa.

Instead, I try to take a more nuanced approach that ties together the available research and my clinical experience with patients trying various diets.

With that in mind, let’s dig deeper into the Volumetrics diet to see if it is an eating plan that could work for you.

What Is the Volumetrics Diet?

The Volumetrics diet was created in 2000 by Dr. Barbara Rolls, a nutrition scientist, and researcher of dietary behaviors at Penn State University.

The fundamental concept of the Volumetrics diet is that when it comes to feeling full, improving satiety, and losing weight, the volume of food (the quantity and how much space it takes up on your plate) you eat is important. 

On Volumetrics, no food is off-limits, but you make high-volume, low-energy-density foods the bulk of what you eat. These tend to be less processed, lower calorie, and higher fiber options, such as whole vegetables, fruits, salads, and legumes. 

Foods with naturally high water content, and meals that have plenty of water incorporated into them, such as soups, broths, and casseroles, are also central to the Volumetrics diet.

Drilling down a little further, the Volumetrics diet categorizes foods into four groups based on their energy (calorie) density. You can refer to one of many charts on the internet (or in one of Dr. Roll’s books) to see which foods are lower or high energy density, but to a certain extent, it is fairly obvious, with high fat and sugar processed and fast foods all being the highest energy density type. 

To find out which category a food belongs in, you can also go full geek and divide the number of calories (in kcal) per serving by the weight of the serving in grams (resulting in a number between 0 and 9):

The idea is that by maxing out on high-volume meals that fill your stomach (i.e. categories 1 and 2 above), you don’t feel as hungry as you would mainly munching on categories 3 and 4. While no category is completely off-limits, you are encouraged to mostly stick to the lower levels.

You are still encouraged to count calories if you are using the Volumetrics diet to lose weight, however. Around 1400 calories per day is recommended for the average user who is trying to lose weight, though this will vary depending on several factors like activity level, gender, height, and current weight

There are four books that have been written by Dr. Rolls on the Volumetrics diet plan, and a host of websites devoted to recipes, so it’s easy to get started.

Volumetrics and Weight Loss

The principles behind the volumetrics diet have been tested in a number of different studies on people seeking to lose weight and tackle obesity, with encouraging results. For example:

• A meta-analysis of 13 studies involving a total of 3628 people found an association between eating low-energy density foods and body weight reduction [1]. 
• Another analysis (on participants from the Nurses’ Health Study II) found that a higher energy density diet was associated with greater weight gain among middle-aged women during 8 years of follow-up. Higher intake of refined carbs, saturated fats, and trans fats were what drove up the energy density of a diet [2].
• A 3-month study with around 100 overweight/obese women found that high-volume, low-calorie density foods lead to decreased cravings, increased feelings of fullness, and reduced hunger [3].
• In one randomized controlled trial, people who ate a bulky salad (100 kcal) as an appetizer ate fewer calories overall at dinner than those who skipped this low-energy density first course [4].

How the Volumetrics Diet Impacts Health

The Volumetrics diet wasn’t specifically designed to tackle health issues, but some health benefits have been recorded, which include:

• Improved cardiovascular health: In a randomized clinical trial (considered a high-quality study design), women who had previously lost weight were assigned either a low energy density diet or a standard diet to maintain their weight. As well as controlling weight more effectively, the low energy density diet produced greater improvements in total and LDL-cholesterol and fasting blood glucose, positively impacting heart disease risk [5].
• Reduced diabetes risk: When diets with a high or low energy density were compared in a large observational study involving over 160,000 postmenopausal women, those who ate the lower energy density diets were at lower risk of developing type 2 diabetes in the future [6].
• Breast cancer: Results from another observational study suggested a modest association between eating a diet with a higher energy density and risk of developing postmenopausal breast cancer [7].

Bear in mind though, that most studies looking at a link between energy density and health have been observational in design, meaning that they can’t prove cause and effect. 

It’s also hard to know if the health benefits of low energy density eating are independent of a weight loss effect. It could be that the benefits occur because people who eat this way lose weight, which improves metabolic health. Lower energy density diets are also lower in fast and ultra-processed foods, so the health benefits described above may simply reflect that more nutritious foods are being eaten.

Also know that the volumetric diet isn’t automatically healthy (for example cheese puffs have a lower calorie density than nuts, but are not healthier)! Making it good for your body requires also considering the nutritional values of the foods you are eating.

Pros and Cons of Volumetrics

One of the major reasons that the Volumetrics plan is generally seen as a healthy diet is that it isn’t a fad diet, and it doesn’t completely eliminate any food groups. This makes it: 

• A sustainable eating regimen, not a quick-fix with severe food or caloric restrictions.
• A great way to reap the health benefits of eating more fruits, vegetables, and lean proteins.
• Suitable whether you eat meat, or are vegetarian or vegan.
• Doable even when you want to include treats or favorite foods. Though high energy density category 4 foods like chips or birthday cake are discouraged, there’s nothing saying you can’t have these on occasion.

Not Gut Friendly for Everyone

However, there are some cons to the volumetrics, particularly if you have gut health issues. Volumetrics encourages a high fiber and prebiotic intake (from fruits, veggies, and whole grains) which, though healthy for many people, can be irritating and cause symptoms like bloating, stomach pain, and gas for those with gut sensitivity.

If you have a digestive disorder like irritable bowel syndrome (IBS), you may find that a Paleo diet or a low FODMAP diet, which eliminates troublesome carbohydrate foods, is better for you and less likely to trigger symptoms [8]. 

More Complicated Than It Needs to Be

While the principles are largely sound, it’s also easy to get bogged down with the math involved in working out what are high and low-energy density foods. Adding in calorie counting adds further complication, and in the worst case scenario could contribute to disordered eating.

Potentially Lacking Good Fats

Another issue I have with the Volumetrics diet is that it recommends reducing the intake of higher-fat foods without there being a distinction between healthy and less healthy fats. 

So for example, nuts, cheese, olive oil, and avocados come under the same “eat less” banner as donuts, chips, fries, and cookies. But the former contain essential fatty acids important for many aspects of health, including hormone production and mental health [9]. 

For some, adding a small amount of fats into your diet daily can help you feel full for longer, prevent blood sugar swings, and discourage unhealthy snacking. If you find that you are constantly searching for something to eat on the Volumetrics diet, a different option that incorporates more fat and higher protein levels — like Paleo — might be a better way to go. 

Is Volumetrics For You?

If you don’t have any significant gut health issues or digestive problems, and have been struggling to keep your weight under control, Volumetrics could be good for you, as long as you don’t neglect those good fats.

However, if you aren’t looking for weight loss, or are clinically underweight, the Volumetrics diet might fill you up before you have a chance to get all the energy and nutrients you need. For this reason, I don’t recommend it for people with poor appetite, who can benefit from plenty of nutritious but more energy-dense foods, such as nuts, meat, and healthier oils (olive and coconut, for example).

Both the energy density measuring and calorie counting of the Volumetrics diet can also be problematic for some people. For example, I don’t recommend calorie counting to my patients who have had, or continue to have, a difficult psychological relationship with food. This complexity can largely be avoided if you just focus instead on minimizing sugary and processed foods and maximizing your fruit and veggie intake. 

The good news is that you can still work with the principles of Volumetrics, (modest portion sizes of low-energy density whole foods) without checking calories. For example, you could simply swap a lunch-time chicken and pesto panini for a big bowl of chicken and veg soup, or try the salad before your meal hack mentioned above (an apple works too).

The key, as with all diets, is to adapt to your needs. But whichever way you make it work, I’d suggest that you focus on nutrient-dense foods first and calories/ weight loss second.

An alternative that many of my patients find works for them is the Paleo diet — this has lots of bulky, unprocessed foods that leave you feeling full, and it works well for weight management. It doesn’t restrict healthy fats, so it can be a good choice for those who want the health benefits of including fatty acids in their diet.

However, approached with a bit of intelligence (we all know that nuts are healthier than cookies), you’ll likely do well with the Volumetrics diet.

Making it Work: The Volumetrics Diet

For most people trying to lose or manage their weight, the volumetrics diet represents a good framework on which to base your food choices. For example, many of the core foods that make up the bulk of what you eat on the diet are phytochemical-rich plant foods and lean protein. 

Done the right way (which means not completely leaving out healthy fats), it encourages you to consume a range of nutritious whole foods that will help you to sustainably manage your weight. 

However, if you do have significant digestive issues, I’d recommend you investigate the Paleo or low FODMAP diets instead.

For help with finding the right diet to match your needs or your health concerns, reach out to us at Ruscio Institute for Functional Health, where we can help on a more personalized basis.

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.