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Volumetrics Diet – Everything You Need To Know

Published: 13th May 2018. Last updated: 21th July 2019.

Matthew Smith

Staff Writer

What Is The Volumetrics Diet?

There are so many crazy diets out there at the moment that when you hear a word such as “volumetrics” you automatically assume that it is going to be completely insane. Well we did. But odd name aside, the Volumetrics diet may actually be that rarest of things … a sensible diet!

No ridiculous concoctions, no enemas, no laxatives, no unscientific “eating windows”, a reliance on exercise – and the ability to eat enough calories to perform said exercise without passing out. It is no wonder that almost nobody on earth has heard of the Volumetrics diet, it’s way to sensible to be popular.

In this review we will take a brief look at the history of the Volumetrics diet, how it works, what is good about the diet, what is bad about the diet, and whether there is any way that we would improve it (if needed).

A Brief History Of The Volumetrics Diet

It may sound crazy, but many of the diets that have become so popular with the general public were created by people with absolutely zero knowledge of nutritional science. Actually, when you think about it, that’s not too crazy at all. No way would an actual scientist create the Lemonade diet (for example).

But Barbara J Rolls is a legitimate nutritional scientist, who has contributed hundreds of journal articles on the subject of satiety (how full you feel after a meal), energy intake, and energy density. You can see how this knowledge has influenced her Volumetrics diet. Barbara is a nutrition professor at Penn State University.

The first dieting book on Volumetrics was published by Barbara Rolls in 1999, it was called “The Volumetrics Eating Plan”. Since then she has published several follow up books that expand on the original.

The diet has been named by US News as the 6th best overall diet, and the 2nd best diet for weight loss. Despite this, the diet has never captured the public’s imagination in the same way that the Atkins diet did – for example.

Possibly because the diet is not controversial enough to be news-worthy, and there are no attention-grabbing aspects to it. When people first heard of the Atkins diet, they heard how carbs were the enemy and that by avoiding them you could transform your physique in weeks.

Volumetrics does not promise you crazy solutions that nobody else has thought about, nor does it offer impossible results. The diet works well and uses a sustainable model that could help prevent weight re-gain.

These are not sexy, exciting talking points. No magazine is going to promote the Volumetrics diet as a fantastic new weight-loss solution, but it is more effective than almost any other diet out there.

How Does The Volumetrics Diet Work?

The Volumetrics diet is based around calorie density. Avoiding foods that are calorie dense and eating foods that have a low-calorie density. This can be tricky to understand, so let’s provide an example. Two tablespoons of peanut butter contain 188 calories. To get 188 calories from broccoli you would need to eat 584g (which is about 20 servings).

It would take you ages to eat that much broccoli (it’s basically two heads of broccoli) and you would feel pretty full afterwards – you would also be sick of broccoli for life!

On the other hand, how long do you think it would take to finish two tablespoons of peanut butter? Ten seconds? How full do you think you would feel afterwards?

Obviously, there is more to the diet than just replacing peanut butter with broccoli – otherwise nobody would ever follow it. But filling up on low-calorie-dense foods rather than calorie-dense foods is at the heart of the Volumetrics diet.

The diet looks to achieve maximal fullness (satiety) with the least number of calories necessary (while still hitting all macro and micronutrient targets). Another focus of the diet is promoting foods that are high in water content.

This is because foods that have a lot of water are more filling without adding any more calories. Soups, casseroles, and stocks are all great examples of low-calorie foods that are satiating. Barbara Rolls believes that a lot of what we eat is down to our brains.

She has published numerous studies which look at (for example) how certain shapes of foods can be more satiating than other. Or how your feeling of fullness is affected by the volume of food that you have consumed rather than the actual number of calories [1].

Rolls does not say that you must avoid certain foods completely, instead she separates all food into four categories [2]:

  • Category #1: Free foods that you can eat anytime. Fruit and vegetables, broths
  • Category #2: Foods that you can eat provided they are measured into decent sized servings. Rice, pasta, lean protein etc
  • Category #3: Foods that you can eat but should keep to small portions. High fat protein sources, bread, cheese, and snacks
  • Category #4. Foods that you should consume in very small amounts. High-fat/high-sugar foods

This is all fairly common-sense when you think about it. “A diet where I eat less junk food and eat more fruit and veg? What a surprise!”. It is for this reason that Volumetrics never really inspired the fanaticism of diets like Keto or Paleo.

A lot of emphasis of the Volumetrics diet is on cooking your own healthy foods. You are advised to eat three meals, two snacks, and a dessert each day, and while this could be done using pre-bought meals, the stated intention is clearly to start from scratch with as many meals as possible.

This is commendable, but some people have found this part to be difficult to fit into their busy lives. Compare it to intermittent fasting which can suit hectic 9-5 days at work. Volumetrics has had a huge influence on If It Fits Your Macros (IIFYM), the dieting practice beloved of bodybuilders and fitness models.

The Positives

There are so many pros to this diet that it’s hard to know where to start. The diet is evidence-based. This means that the information you are receiving has been studied and found to be effective by scientists. This is a big deal. Most diets are not based on science, but are often based on opinion, anecdotal evidence, and sometimes outright lies!

The diet allows you to eat what you want but limits you to only eating small amounts of calorie-dense foods. You can have your cake, but you’ll need to fit it into your daily allowance.

This helps people psychologically. The difference between banning a food completely and allowing that same food but empowering the dieter to eat with caution is huge. How many diets do you know of that schedule in a daily dessert?

But imagine the difference between eating a scheduled dessert each day which you know fits into your calorie allowance compared to eating a BANNED dessert that has WRECKED your diet. Who do you think will be chucking that diet out the window sooner?

Another benefit of this diet is that it is all about eating as much as you can. Not calorie-wise (obviously), but in terms of volume. By prioritizing foods that are not calorie-dense you are able to eat a higher volume of food without blowing out your calorie targets.

This means you’ll spend less time hungry throughout the day, and mentally you’ll feel full even though you’re actually consuming less calories than usual. One of the biggest problems with most diets is the cravings you get between meals.

But if you’ve eaten the biggest breakfast ever (in terms of volume) then you’re not going to have to worry about that. This will help you stay on the wagon longer (hopefully indefinitely) and therefore the diet will be a long-term success rather than a short-term one.

Because almost any diet can get you short-term results, often the worst diets get the quickest results. But they aren’t sustainable. People should stop thinking of dieting as a short-term solution, if you want to lead a long and healthy life with a lean physique then you need to be in this for the long haul.

The volumetrics diet allows you to do so.

The volumetrics diet also stresses the importance of exercise, this is important because losing weight through dieting alone can cause future issues. Dieting can lead to fat loss of course, but it can also lead to muscle loss – particularly if protein is low.

But exercise can help to prevent muscle loss, which means your metabolism should be unaffected, your muscles will appear toned, and you will also be able to create a slightly larger calorie deficit (which means more weight loss).

So many diets treat exercise as an inconvenient addition – or they go to the other extreme, and place all of the importance on exercise while diet is little more than an afterthought. This diet sees exercise and diet as two vital factors in weight loss, one should not be prioritized over the other, as both are essential.

The Negatives

One of the most common criticisms of the volumetrics diet is that so much of it relies on people cooking their own meals – which is seen as unrealistic. In a way this is a con. If something is difficult to do then most people will not do it.

But what are the other solutions here?

Is it fair to criticize a diet for asking people to cook their own food? Because that’s a fairly normal part of dieting. There are ways to speed up the process by batch cooking, finding quicker methods for prepping (using frozen diced onions rather than fresh for example), or editing recipes to suit time constraints.

With practice, most people can find numerous ways to speed up the prep and cooking process, and these people will be successful. Yes cooking takes time. But so does working out in a gym, so does learning a new language, or becoming an stockbroker. Life is hard, and if you want real success then you need to work harder than most people are prepared to.

Most diets fail, even the ones that are thought of as initially successful will often have failed within two years. Could it be that trying to make dieting as easy as possible straight away is the common mistake for all of these diets.

Yes, the requirement to cook your own meals is a con, but it is also vital to the success of the diet. Cooking your food will help you learn more about nutrition, will help you eat more fruit and veg, will help you to eat more protein, will help you take control over what goes into your mouth.


If you have a wedding that you need to lose a ton of weight for within the next two weeks, then the volumetrics diet is not for you. This is the type of diet that should be started after New Years, with a long-term goal in mind. “This time next year I want to have lost some excess body fat and kept it off while still eating lots of delicious food”.

If that is your goal, then volumetrics diet is well worth the effort. It will be much more enjoyable than any extreme diet. It will allow you to eat all sorts of foods, and you can drink broth until it is pouring out your ears.

You might not see instantaneous results but follow it for 12 weeks and you’ll definitely notice the difference. Then use the knowledge gained to help maintain your new figure. You’ll be forever grateful to Barbara J Rolls.

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