Friday, February 20, 2009

Volumetrics: Practical application of the obesity research

The top of the diet book list: More Taste, More Filling, Less Calories

My review of "The Volumetrics Weight Control Plan" by Barbara Rolls, PH.D. and Robert A. Barnett, HarperCollins, 2000.

There are thousands of diet books out there promoting approaches with varying combinations of common sense, science, experience, and novelty in their approach to weight control. They each have their advocates. I think Volumetrics is at the very top of the list of approaches for a number of reasons.

First is credibility. Barbara Rolls is not a personal trainer or a celebrity or "nutritionist" in the generic sense or someone who read a handful of studies and observed a handful of clients to derive her conclusions, she is a leading nutrition and health researcher. She knows the trends and patterns in the research, she knows which approaches have been reliable and which have not in the long run and with the widest base of people. Her foundation in the science of weight control is as solid as anyone writing about nutrition, and much better than 99.9% of the authors.

Second is flexibility. Volumetrics is not a concept based on sensory-specific boredom or food restriction, common and very popular approaches which generally are self-defeating. Volumetrics is instead based on understanding our own feelings of satisfaction with food so that we can feel satisfied while meeting our health goals rather than depriving ourselves. There are a number of effective tactics in Volumetrics for eating in a way that is satisfying and does not restrict food yet does restrict calories and therefore control weight. These tactics are not all or nothing, you can apply the ones you need to the degree that you need without following rigid rules and dietary restrictions. The tactics are organized in modular fashion. You can apply these principles when you go out to eat or order take-out or prepare your own favorites or you can make your own Volumetric meals from scratch, or any combination of these. Most of the time you are not avoiding foods at all, you are actually adding new ones in to help satisfy hunger so you don't need as much of the ones you crave in order to feel satisfied.

Third is variety. Unlike most programs, Volumetrics takes advantage of our natural inclination to eat a variety of foods in order to get the wide variety of nutrients that we need for optimal health. Most programs recognize that variety triggers us to eat more, so they discourage it and encourage boredom but we eventually get bored of nutritional boredom. Volumetrics instead encourages variety but provides a variety of choices that help rather than hurt weight control goals.

The central concepts are probably not going to be new to anyone who reads diet books. The presentation of their scientific basis and the reason why they work in terms of modern obesity research models is the strength of this book, and having this rationale is what allows the principles to be applied more flexibly. If you understand the *why* of the food choices, you can improvise flexibly in your own application of the program, and that's what Volumetrics gives you.

The key principle is satiety. Research indicates that in the long run we tend to eat until we are satisfied and we know we are satisfied in two ways. First, a complex collection of physiological signals from various parts of the body combine to produce the experience of satiety itself. Then we also learn what behaviors and foods lead to the experience of satiety for us. The Volumetrics approach centers around learning how to effectively produce the experience of satiety with what we eat and how to retrain our expectations for what we need to eat to be satisfied. That's it, the rest is details.

The main detail is the concept of energy density. Another important consistent research result is that people tend to eat the same amount by weight because of how we've learned to satisfy our hunger. The key result that makes the Volumetrics approach workable is that we can trigger the same signals that a particular weight of food produces with an equal volume of more satisfying, less energy-dense food. By deliberately creating the right sensory experience and fullness with foods that have less caloric energy, we learn to satisfy our hunger with less calories and so lose weight while eating more healthy and less calories.

The important point is that this is not about just eating salads and soups all the time, it is about strategically getting good nutrition by knowing the relative energy density of foods and eating more of the low energy density foods we really enjoy, and then more strictly portion control the higher energy density ones we have been craving and have been obstacles to our health goals. The emphasis on satiety in low-density foods controls the cravings for the high-density ones, making this possible.

This probably sounds a lot like common sense, and I think much of it is. However the details and their scientific rationale are what really make the program in this book stand out and make it workable and flexible. Volumetrics explains the specific problems with various other approaches like high protein/low carb and presents a broadly workable and scientifically based alternative that give you good lifelong nutritional habits rather than a tricky way to lose weight for a few weeks. I've been gradually incorporating these principles into my own life for several years and have been very happy with both their sustainability and their effectiveness. I think this program is going to be they key to weight control for a lot of people.

Given that the treatment of weight control in this book is so good, let's look at the few limitations.

First, since it is written from the perspective of health, there is really no treatment of performance or athletic nutrition, so athletes interested in weight control may be able to use these principles but they will not be able to rely on this book for their complete nutritional program.

Second, a related limitation is that the treatment regarding exercise is rather weak compared to the treatment of nutrition. Guidelines for walking and moderate activity are emphasized particularly for weight maintenance where they are most effective, rather than weight loss. The Volumetric approach is consistent with the trainer's dictum "you can't out-train a bad diet." Only a competitive endurance athlete and few extremes of that sort can hope to move so much that they burn off an energy-dense diet. So the principles of weight loss emphasize calorie restriction and satiety rather than exercise. As Volumetrics explains, exercise becomes important in three ways for weight *maintenance* (rather than loss) however: (1) strength training builds lean mass which raises resting metabolism, so we don't need to restrict calories as much, and (2) activity itself is more successful at maintaining weight than losing it, once we have eating patterns that maintain a nearly stable weight, and (3) a good exercise program is extremely effective at increasing our sense of self-efficacy, which leads to compliance and success in other habits as well. The limitation is that the book offers no help in what makes a good exercise program effective in these ways. It is not a book about exercise. High intensity exercise is mentioned as possibly even more useful for people who can tolerate it. I think this aspect is very important and should have been discussed a bit more. However it is a large book with a lot of details on its core principles, and exercise is really just a secondary concern to the authors.

Third, there is really very little discussion of popular principles that just aren't effective or those that possibly might be useful. The authors explain that most diets succeed in the short term because of various kinds of boredom and appetite suppression rather than because they are sound eating patterns. And they explain why adequate protein is important but more than that is not particularly helpful in the long run for weight control. But all of the rest of the tactics are left pretty much untouched. It would have been useful for some of the more intriguing ones to have been addressed, such as intermittent fasting.

Fourth, the thoroughness of the book will also be its downfall for some less patient readers used to reading web pages rather than books. This is a real book, not a pamphlet. It doesn't give you a condensed program in abstract form in the first few pages, you have to read the book and digest its lessons in order to get its full education and apply them effectively and flexibly. That's the whole point of the program, at least from my perspective, that deeper knowledge of the principles will help you with lifelong better eating.

All in all, I'd say this is the best single book on general principles of lifelong nutrition for weight control, it is detailed, comprehensive, and authoritative, and the program is practical, flexible, and sustainable. I'd venture so far as to say that other programs probably succeed or fail largely on how well they apply the sound principles behind Volumetrics.

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