Manipulating your food choices is the key to losing and managing weight. That is what diets do.
In addition to promoting the idea of eating less to lose weight they also suggest to cut or add on certain food groups. There are low fat, low carb and even high protein diets and some people seem to be fine on it.
However for some it gets very arduous to cut out on an entire food group. Also it’s easy to lose weight in comparison to maintaining it. And most dieters tend to fall weak to the attack of hunger and relapse.
Dr. Barbara Rolls seems to have solution for these pitfalls. As a professor of nutritional sciences at Penn State University, she conducts a lot of research on how to tackle obesity and improve nutrition. She came up with the Volumetrics diet back in 2000 and has published three books on it till date.
The Volumetrics diet has been ranked No. 6 out of 32 in Best Diets Overall category of the U.S. News & World Report’s Best Diets 2014 and No. 5 in the category of Best Weight Loss Diets.
What is Volumetrics diet?
Volumetrics diet is based on the idea of ‘Feeling Full on Lower Calories’ or ‘Eat More and Weigh Less’ which is perhaps everybody’s dream but nevertheless it comes with a slight catch. And the catch is what exactly you can eat more of.
The key component that Dr. Rolls intends to influence with this diet is satiety. Unlike some strict calorie restricting diets which leave you hungry, this diet aims to have a satisfactory rating of fullness and hunger from the consumer. So the idea is to eat till you are full and still lower your calorie intake.
Dr. Rolls categorizes food into four groups: [You will understand what energy density is in the next section]
- Category 1 (very low energy density foods): Non starchy fruits and vegetables, soup, low fat milk
- Category 2 (low energy density foods): starchy fruits and vegetables, grains, lean protein, legumes, low fat dairy
- Category 3 (medium energy density foods): breads, desserts, high fat meat, fat free baked snacks
- Category 4 (high energy density foods): snacks, candies, nuts, fats and fried foods
One can eat 3 meals, 2 snacks and 1 dessert each day. However you eat more of category 1 and 2, watch the portion size of category 3 and category 4 should be bare minimum. While preparing your meals you can replace category 4 ingredients with category 1 and 2 components and still have your favourite dish.
The other vital component is physical activity. Dr. Rolls recommends regular exercise as it has health benefits beyond weight loss. Apart from physical health, it improves mental health by improving mood and reducing anxiety. The plan includes exercises that burn 100, 200 or 250 calories and duration of 150 minutes of exercise per week is recommended.
What does this mean?
Volumetrics diet revolves around two principles:
-Eating foods that promote satiety and still provide less calories
-Performing adequate physical activity each day to burn sufficient calories.
How does Volumetrics work?
To understand how you can eat more and still weigh less, you have to first understand the term ‘energy density’. Energy density is the number of calories packed in 1 gram of the food item.
Some foods pack a lot of calories in 1 gram and are highly energy dense whereas some pack lesser calories in the same weight and low energy density foods. You can observe this even in case of macronutrients:
- Fat is extremely energy dense and packs 9 calories in 1 gram.
- Alcohol packs 7 calories in 1 gram.
- Proteins and carbs account for 4 calories in 1 gram.
- Fibre is a type of carbohydrate but provides only 2 calories per gram as it not completely digested or absorbed in the body.
- Water is the magic component that has 0 calories.
Roughly a person tends to eat the same weight of food over a period of 1-2 days. So we know the amount of food we require to satisfy our hunger. Dr. Rolls has observed in her experiments that people tend to eat similar amounts of food irrespective of calorie content.
So the Volumetric diet is designed to lower calorie content of your regular amount of food so that you are not left hungry. This makes it easier to stick to the diet and you land up eating fewer calories and losing weight.
Few examples as to how you can practise this concept:
- By skipping butter you can two slices of bread instead of 1 buttered slice at same calories.
- Replace pepperoni and cheese in your homemade pizza with lean bacon, low fat cheese and tomatoes.
- You can have 2 glasses of skim milk than 1 glass of whole milk at same calories.
- Have foods rich in water and fibre.
- For 100 calories you can eat 2 cups of grapes instead of 1/4th cup of raisins.
This plan focuses on ‘what you can eat and not what you can give up’. Additionally the inclusion of exercise assures that you can burn calories and have a low calorie day always. It teaches you how to fit your favourite foods in your diet and how to follow sustainable nutritious eating patterns that last for lifetime.
What does this mean?
Volumetrics diet focuses on eating low energy dense foods- foods that provide lesser number of calories per unit weight of food. This means eating foods rich in water and fibre such as fruits and vegetables. However the diet does not restrict your favourite foods.
Just watch the portion and use less energy dense ingredients.So you practically eat the same amount of food each day but your calorie intake is low. This puts your body in an energy deficit and it burns excess fat making you lose weight.
What does science have to say about the concept of energy density and weight loss?
The role of energy density in energy intake and weight management has been well studied and this is what the scientific data points out to.
Low energy dense foods are associated with better diet quality
A survey in US population revealed that those consuming low energy dense foods had reduced energy intake but consumed more food. The low energy density diet was characterized with nutritious food, low in fat and high on fruit and vegetables.
Also individuals following this diet drank less of caloric beverages. Risk of obesity was low in such individuals.
An observational study conducted in Spain reported that manipulation of energy density is essential for efficient nutrition.
A European study associates lowering energy density with beneficial effects on abdominal obesity.
What does this mean?
Low energy dense foods are rich in nutrients, water and fibre. Those who consume more of low energy dense foods are less prone to obesity.
Low energy dense foods promote satiety and reduce calorie intake
Low energy dense diets directly affect satiety signals. A 12 month study demonstrated that reduction in energy density led to weight loss by altering satiety related hormones such as ghrelin and PYY.
Preload is a scientific term for entree, though not always. Basically you are given something to eat prior to the main course in order to assess your appetite subsequently.
In this study women were given a small or large portion of salad of varying energy density and thereafter they were served pasta for lunch. The control group did not receive any salad.
It was observed that those consumed low energy dense salad reduced intake by 7% and 12% whereas those who consumed high energy dense salad increased intake by 8% and 17%.
Despite of the same number of calories in the salad, energy intake was reduced when consuming large portion of low energy dense salad and the consumers also felt full.
A similar study was conducted in children (2-5 years of age) wherein energy density of entrees (macaroni and cheese) were altered and thereafter the kids were given an unrestricted lunch. Decreasing energy density of entrees by 30% reduced energy intake by 25% from entree and 18% at lunch.
Several other studies have confirmed that, when individuals consume meals lower in energy density, their daily energy intake is significantly lower than when they consume meals higher in energy density.
What does this mean?
Since low energy dense foods pack less calories in unit weight of food you can have more portions and feel satisfied.
Having such foods prior to meals reduces your calorie intake at meals. This weight loss strategy has been proven in children and adults.
When the ED is lowered, you can skip ‘Reduce the fat’ rule
The Volumetrics diet permits you to eat any food group as long as you manage the portion and energy density. Fat is generally overconsumed due to its low effect on satiety and high energy density. Therefore manipulating energy density allows you to have the same amount of food but low calories and the fat content doesn’t matter.
A study was conducted wherein participants were given entrees of varying fat content and energy density. It was found that energy density influenced energy intake of all fat contents and the usual trend of low energy density associated with lower energy intake was followed.
Another similar study wherein the portion was also manipulated reported that it was the energy density rather than fat content that reduced the overall energy intake. Portion size and energy density have independent but additive roles in reducing calorie intake.
Research showed that a 25% decrease in portion size led to a 10% decrease in energy intake (231 kcal/d), and a 25% decrease in energy density led to a 24% decrease in energy intake (575 kcal/d) and this effect was seen over the period of 2 days.
A review study reports that advising individuals to eat low energy density foods in controlled portion sizes is a better strategy to reduce calorie intake than reducing fat content.
What does this mean?
Lowering energy density of the food reduces your calorie intake to an extent that you don’t need to worry about the fat content of your food. However that does not mean all fats are healthy.
Lowering energy density fares better than other dietary weight loss techniques
Raynor et al conducted a study for 3 months involving overweight/obese individuals who were assigned to following groups:
- Low calorie and low fat diet
- Low energy density, low calorie and low fat diet
- Low energy density diet
All 3 diets led to weight loss and increased physical activity and fruit intake. But weight loss in the low energy density diet was maximum (20 lb).
Another scientific setting suggests that lowering energy density is as effective as portion control and low glycemic index diets in reducing weight and improving parameters of metabolic syndrome. In a clinical trial , participants were allotted two groups.
Group 1 was asked to include satisfying portions of low energy density foods like fruits, vegetables, broth based soups and prepare food with low fat.
Group 2 were asked to cut down on all food groups and reduce fat intake. After 6 months group 1 (20lb) experienced 40% greater weight loss than group 2 (15 lb) and they also had a higher diet quality.
What does this mean?
Low energy density diet is as good as or even better than other weight loss diets in which you are asked to restrict food groups.
Critical question: Can you eat satisfying portions and still lose weight?
If you religiously follow The Ultimate Volumetrics Diet or The Volumetrics Eating Plan the answer to this question is yes. The plan reduces your daily overall intake and incorporates exercise so it is logical to think that the diet will lead to weight loss.
A 1 year study comparing the effect of lowering fat intake with lowering fat intake and increasing consumption of water rich fruits and vegetables reported that the second group (8kg) lost significantly more weight than first group (6.4 kg) .
The PREMIER trial has been designed to study lifestyle interventions in order to control blood pressure. One such intervention was exploration of the relation between reducing energy density and weight loss. In this study, groups were given different dietary recommendations including the DASH (Dietary Approaches to Stop Hypertension) approach.
After 6 months all groups had reduced energy density which resulted in reduced energy intake and body weight. Maximum weight loss of 5.9kg was observed.
Research shows that weight loss maintainers have a diet lower in energy density characterized by greater intake of fruits, vegetables and grains.
A review of 17 studies suggests that lowering energy density is an effective strategy for weight loss and maintenance in children and adolescents.
The University of Alabama at Birmingham EatRight Weight Management Program promoted consumption of low energy dense foods and healthy carbs. Average weight loss was 4kg. Post follow up 46% did not regain weight or continued losing weight and those who did gain only gained less than 5% of the weight lost.
However a review of 92 studies focussed on lowering energy density as a weight loss strategy revealed that it works only for short term and not in long term. But again the authors state that this conclusion is based on the results of limited long term clinical trials and support the need for long clinical trials on this concept.
A 4 year study in breast cancer survivors reported insignificant changes in weight by manipulating energy density.
What does this mean?
Short term clinical trials provide strong evidence of reduction of calorie intake when following Volumetrics diet.
Additionally most long term trials, given the exception of a few, also suggest that this reduction of daily calorie intake translates into substantial weight loss in 1 year or more.
What dietary strategies can help in lowering energy density of the meal?
A 1 year study assessing the effects of vegetable intake and weight loss reported an average loss of 6.5 kg and reduction in heart disease risk factors. Fruits are low calorie foods that are high on fibres.
Soups despite of being liquids are considered as food and the debate is whether food in liquid form can affect satiety just as much as solid foods. To test this, a study was conducted wherein form of the soup was altered: broth and vegetables served separately, chunky vegetable soup, chunky-pureed vegetable soup, or pureed vegetable soup.
It was observed that consuming a low energy dense soup reduced energy intake by 20% and the type of soup did not affect alter the effect.
A long term study showed that consuming 2 servings of low energy dense soup daily leads to 50% greater weight loss than consuming high energy density snacks.
Silver et al also prove the same premise that inclusion of low energy dense food (grapefruit or grapefruit juice) prior to a meal curbs appetite and translates into weight loss and the form of food doesn’t matter.
Replacing red meat with mushrooms in diet is an effective way to reduce energy density and lose weight. This study reported a 7lb decrease in 12 months.
What does this mean?
Consuming veggies and fruits, adding water and vegetables to your meals or going for low fat options are few of the ways you can lower energy density of the meals.
Additionally you can refer to Dr. Rolls book where she has provided 100+ low energy dense food recipes.
The Volumetrics diet is a pretty simple diet which does not restrict any food group or the quantity of food and that is perhaps the best part about this diet. All it asks you to do is go for healthier alternatives to your current diet without compromising on taste and fullness after a meal.
It also incorporates physical activity which serves as another measure to protect you from weight gain and improves your health. It is a great diet for someone wanting to lose weight or even for someone who wants to have healthier eating habits.
Among the different diets I have come across this is one of the best diets for weight maintenance irrespective of whatever diet you have tried earlier. More than a diet I would call this a healthy style of eating.