Human Nature: Science, Technology, and Life.

The Mind-Body Dieting Problem

In the latest study, published in the New England Journal of Medicine, "participants were assigned to and taught about diets that emphasized different contents of carbohydrates, fat, and protein and were given reinforcement for 2 years through group and individual sessions." Result: "The diets were equally successful in promoting clinically meaningful weight loss and the maintenance of weight loss over the course of 2 years."

Why did different diets produce similar results? Not because they're similar on paper, but because they were similarly disobeyed by actual human beings.

Few of the people in the current study strictly adhered to the calorie limits and the composition of their diets, suggesting it is just too difficult to do so ... For example, those assigned to consume 35% of their calories as carbohydrates actually consumed an average of 43%, and groups that were supposed to eat a 20%-fat diet averaged 26%. In the end, many of the participants were eating diets that were more similar than dissimilar.

This study and others "point to behavioral factors rather than macronutrient metabolism as the main influences on weight loss," the authors conclude. "The effect of any particular diet group is minuscule, but the effect of individual behavior is humongous," says lead author Frank Sacks. We had some people losing 50 pounds and some people gaining five pounds."

In short, as Human Nature has argued before, compliance is part of a diet's effectiveness. If you can't stick to a diet, don't just blame yourself. Change the diet. If you can't stand the kale and couscous, stop kidding yourself, and find palatable alternatives.

And when I say palatable, I mean that literally. Diets "tailored to individual patients on the basis of their personal and cultural preferences" may "have the best chance for long-term success," the authors of the new study conclude. According to the Associated Press, Sacks explicitly says the key is to choose a diet that's "tasty." Another researcher, Christopher Gardner of Stanford University, adds, "If one of these approaches is more satiating, where you will not be hungry and have cravings, that is the one that will work for you."

So enough with the quarrels about this or that magic diet for re-engineering your body's chemistry. Think less about your body and more about the part of you whose compliance determines whether the diet has a shot at working: your mind. Is the kale tasty enough? Is the tofu satiating? If not, leave that diet to the saints, and find one that works for the rest of us sinners.

Your Great Idea Here

Human Nature is on vacation and won't be back till after New Year's. In the spirit of the holidays, I'd like to thank each of you for staying in touch as a reader and, I hope, as a correspondent. In fact, I'd like to ask one favor of you: Tell me how you'd like me to do my job differently.

The mission of this column is to explore the ways in which science and technology are changing how we live, what we think, and who we are. It's a huge and growing part of modern life. Traditional media have covered it poorly, I think, because they're too accustomed to the old system of beats. There's the science beat, where you cover the latest studies. There's the health beat, where you cover the human body. And then there are political and cultural beats, which address how we live and govern ourselves.

The problem with the old system is that technology is moving so fast, and transforming society so extensively, that we can no longer adequately cover politics and culture without accounting for science and technology. Nor can we cover science and technology without examining how they're affecting culture and politics. Hence this column.

With that framework in mind, which topics should I be covering more? Which developments am I missing? Which questions am I neglecting to ask? And while you're at it: Which formats do you prefer to read? How often do you want to be updated? Do you prefer the longer pieces of previous years? The quick headline links of last spring? The daily, medium-length blog items of the last month or so? Something else?

Who are your favorite writers on science and technology? Your favorite news sources? Your favorite blogs? Last spring I drew up a list of blogs and news outlets. I'll probably adapt it to run in the right-hand column of this page. Should I add to it? If I narrow it, which links should I keep? Got any good books to recommend?

One thing I've come to admire about science, as opposed to politics, is its humility. Today's proudest theories are always at the mercy of tomorrow's inconvenient data, and today's seemingly straightforward data are always open to being reshuffled by tomorrow's perspective-shifting theories. We have a lot to learn from each other.

So give me your best advice. I can't learn without you. And I'll be back to return the favor in 2009.

Diets and Reality

There's quite a dustup over the diet study published today in the New England Journal of Medicine. The study reports that for two years, 322 "moderately obese" people were assigned "to one of three diets: low-fat, restricted-calorie; Mediterranean, restricted-calorie; or low-carbohydrate, non-restricted-calorie." On average, each participant lost 6 to 10 pounds.

In her New York Times blog, Tara Parker-Pope laments the study's findings. "All it really showed is that dieters can put forth tremendous effort and reap very little benefit," she writes. Her report is headlined, "More Evidence That Diets Don't Work."

Diet guru Dean Ornish disagrees. Writing in Newsweek, he calls the study "extremely flawed" because participants "on the ‘low-fat' diet decreased their total fat intake from 31.4 percent to 30.0 percent, hardly at all." Their diet "was based on the American Heart Association (AHA) guidelines, which I have long criticized as not being enough of a change in diet to show much benefit."

Which writer is correct? Both, and neither. The study's lesson isn't that "diets don't work" or that the only diets worth studying are more radical. The lesson is that there's a tradeoff between results and compliance.

Look at the study's abstract on the NEJM Web site. It begins, "Background: Trials comparing the effectiveness and safety of weight-loss diets are frequently limited by short follow-up times and high dropout rates." Scroll down, and you'll see that the first finding reported isn't average weight loss. It's compliance. "Results: The rate of adherence to a study diet was 95.4% at 1 year and 84.6% at 2 years."

In other words, the study was designed in part to measure the cost of making diets easy enough to maintain. The lead author makes this clear in an interview with Parker-Pope:

In order to keep participants on the diet for long term as a way of life, we did not impose extreme diet protocols. More dramatic diet protocols could probably reduce more weight for the short term, but participants would have dropped out.

So Parker-Pope is right that the average weight loss was depressingly modest, and Ornish is right that more radical diets would probably have produced better results. But Ornish is wrong that this amounts to a damning flaw in the study, and Parker-Pope is wrong that it shows "diets don't work." The study set out to see what would happen if people were put on diets that the vast majority of them could psychologically sustain for two years. What happened was that by making the diets sustainable, the researchers made them less potent at reducing weight.

I've said this before, and I'll say it again: Compliance is part of a diet's effectiveness. Unless you plan on jailing people and sliding food under the door, their ability and willingness to adhere to the regimen are crucial factors in whether it works. If you want to complain about flaws in diet studies, complain about the studies with high dropout rates, which conveniently eliminate the real-world failure of diets that reduce weight if perfectly followed but are, for too many people, unsustainable.

This study isn't one of them. The news it brings is bad but important: We have to figure out how to design diets that are both potent and sustainable. We're not there yet.