Obesity is a national health crisis—that  much we know. If current trends continue, it will soon surpass smoking in the U.S. as the biggest single factor in early death, reduced quality of life and added health care costs. A third of adults in the U.S. are obese, according to the Centers for Disease Control and Prevention, and another third are overweight, with Americans getting fatter every year. Obesity is responsible for more than 160,000 “excess” deaths a year, according to a study in the Journal of the American Medical Association. The average obese person costs society more than $7,000 a year in lost productiv­ity and added medical treatment, say researchers at George Washington University. Lifetime added medical costs alone for a person 70 pounds or more overweight amount to as much as $30,000, depending on race and gender.

All this lends urgency to the question: Why are extra pounds so difficult to shed and keep off? It doesn’t seem as though it should be so hard. The basic formula for weight loss is simple and widely known: consume fewer calories than you expend. And yet if it really were easy, obesity would not be the nation’s number-one lifestyle-related health concern. For a species that evolved to consume energy-dense foods in an environment where famine was a constant threat, losing weight and staying trimmer in a modern world of plenty fueled by marketing messages and cheap empty calories is, in fact, terrifically difficult. Almost everybody who tries to diet seems to fail in the long run—a review in 2007 by the American Psychological Association of 31 diet studies found that as many as two thirds of dieters end up two years later weighing more than they did before their diet.

Science has trained its big guns on the problem. The National Institutes of Health has been spending nearly $800 million a year on studies to understand the metabolic, genetic and neurological foundations of obesity. In its proposed plan for obesity research funding in 2011, the NIH lists promising research avenues in this order: animal models highlighting protein functions in specific tissues; complex signaling pathways in the brain and between the brain and other organs; identification of obesity-related gene variants; and epigenetic mechanisms regulating metabolism.

This research has provided important insights into the ways proteins interact in our body to extract and distribute energy from food and produce and store fat; how our brains tell us we are hungry; why some of us seem to have been born more likely to be obese than others; and whether exposure to certain foods and toxic substances might modify and mitigate some of these factors. The work has also given pharmaceutical companies numerous potential targets for drug development. What the research has not done, unfortunately, is make a dent in solving the national epidemic.

Maybe someday biology will provide us with a pill that re­adjusts our metabolism so we burn more calories or resets our built-in cravings so we prefer broccoli to burgers. But until then, the best approach may simply be to build on reliable behavioral-psychology methods developed over 50 years and proved to work in hundreds of studies. These tried-and-true techniques, which are being refined with new research that should make them more effective with a wider range of individuals, are gaining new attention. As the NIH puts it in its proposed strategic plan for obesity research: “Research findings are yielding new and important insights about social and behavioral factors that influence diet, physical activity, and sedentary behavior.”

How We Got Here
The desperation of the obese and overweight is reflected in the steady stream of advice pouring daily from sources as disparate as peer-reviewed scientific journals, best-selling books, newspapers and blogs. Our appetite for any diet twist or gimmick that will take the pounds off quickly and for good seems to be as insatiable as our appetite for the rich food that puts the pounds on. We, the public, love to believe in neat fixes, and the media oblige by playing up new scientific findings in headline after headline as if they are solutions.

It doesn’t help that the scientific findings on which these headlines are based sometimes appear to conflict. For example, a study in September’s American Journal of Clinical Nutrition found a link between increased dairy intake and weight loss, although a meta-analysis in the May 2008 Nutrition Reviews discovered no such link. A paper in the Journal of Occupational and Environmental Medicine in January 2010 postulated a connection between job stress and obesity, but in October a report in the journal Obesity concluded there was no such correlation. Part of the problem, too, is that obesity researchers are in some ways akin to the metaphorical blind men groping at different parts of the elephant, their individual study findings addressing only narrow pieces of a complex puzzle.

When the research is taken together, it is clear that the obesity fix cannot be boiled down to eating this or that food type or to taking any other simple action. Many factors contribute to the problem. It is partly environment—the eating habits of your friends, what food is most available in your home and your local stores, how much opportunity you have to move around at work. It is partly biology—there are genetic predispositions for storing fat, for having higher satiety thresholds, even for having more sensitive taste buds. It is partly economics—junk food has become much cheaper than fresh produce. And it is marketing, too—food companies have become masterful at playing on human social nature and our evolutionary “programming” to steer us toward unhealthy but profitable fare. That is why the narrow “eat this” kinds of solutions, like all simple solutions, fail.

When we go on diets and exercise regimens, we rely on willpower to overcome all these pushes to overeat relative to our activity level. And we count on the reward of getting trimmer and fitter to keep us on the wagon. It is rewarding to lose the weight, of course. Unfortunately, time works against us. As the weight comes off, we get hungrier and develop stronger cravings and become more annoyed by the exercise. Meanwhile the weight loss inevitably slows as our metabolism tries to compensate for this deprivation by becoming more parsimonious with calories. Thus, the punishment for sticking to our regimen becomes increasingly severe and constant, and the expected reward recedes into the future. “That gap between the reinforcement of eating and the reinforcement of maybe losing weight months later is a huge challenge,” says SungWoo Kahng, a neurobehaviorist who studies obesity at the Johns Hopkins University School of Medicine and the Kennedy Krieger Institute.

We would be more likely to stick with the regimen if it remained less punishing and more reliably rewarding. Is there a way to make that happen?

From Biology to Brain
The most successful way to date to lose at least modest amounts of weight and keep it off with diet and exercise employs programs that focus on changing behavior. The behavioral approach, tested over decades, involves making many small, sustainable adjustments in eating and exercise habits that are prompted and encouraged by the people and the rest of the environment around us.

The research in support of behavioral weight-loss approaches extends back more than half
a century to Harvard University psychologist B. F. Skinner’s development of the science of behavioral analysis. The field is founded on the notion that scientists cannot really know what is going on inside a person’s brain—after all, even functional MRIs, the state of the art for peering into the mind, are crude, highly interpretable proxies for cognition and emotion that reduce the detailed firing of billions of neurons in complex circuits to a few blobs of color. But researchers can objectively and reproducibly observe and measure physical behavior and the immediate environment in which the behavior occurs, allowing them to identify links between environment and behavior. That typically includes trying to spot events or situations that may be prompting or triggering certain behaviors and noting what may be rewarding and thus reinforcing of some behaviors or punishing and thus inhibiting of others.

The effectiveness of behavioral interventions has been extensively documented for a wide variety of disorders and problem behaviors. A 2009 meta-analysis in the Journal of Clinical Child & Adolescent Psychology concluded that “early intensive behavioral intervention should be an intervention of choice for children with autism.” A systematic review sponsored by the U.S. Pre­ventive Services Task Force found that even brief behavioral counseling interventions reduced the number of drinks taken by problem drinkers by 13 to 34 percent for as long as four years. Review studies have found similar behavioral-intervention successes in challenges as diverse as reducing stuttering, increasing athletic performance and improving employee productivity.

To combat obesity, behavioral analysts examine related environmental influences: Which external factors prompt people to overeat or to eat junk food, and which tend to encourage health­ful eating? In what situations are the behaviors and comments of others affecting unhealthful eating? What seems to effectively reward eating healthfully over the long term? What reinforces being active? Behavior-focused studies of obesity and diets as early as the 1960s recognized some basic conditions that seemed correlated with a greater chance of losing weight and keeping it off: rigorously measuring and recording calories, exercise and weight; making modest, gradual changes rather than severe ones; eating balanced diets that go easy on fats and sugar rather than dropping major food groups; setting clear, modest goals; focusing on lifelong habits rather than short-term diets; and especially attending groups where dieters could receive encouragement to stick with their efforts and praise for having done so.

If these strategies today sound like well-worn, commonsense advice, it is because they have been popularized for nearly half a century by Weight Watchers. Founded in 1963 to provide support groups for dieters, Weight Watchers added other approaches and advice in keeping with the findings of behavioral studies and used to bill itself as a “behavior-modification” program. “Whatever the details are of how you lose weight, the magic in the sauce is always going to be changing behavior,” says nutrition researcher and Weight Watchers chief science officer Karen Miller-Kovach. “Doing that is a learnable skill.”

Studies back the behavioral approach to weight loss. A 2003 review commissioned by the U.S. Department of Health and Human Services found that “counseling and behavioral interventions showed small to moderate degrees of weight loss sustained over at least one year”—a year being an eon in the world of weight loss. An analysis of eight popular weight-loss programs published in 2005 in the Annals of Internal Medicine found Weight Watchers (at that time in its pre-2010 points-overhaul incarnation) to be the only effective program, enabling a 3 percent maintained body-weight loss for the two years of the study. Meanwhile a 2005 JAMA study found that Weight Watchers, along with the Zone diet (which, like Weight Watchers, recommends a balanced diet of protein, carbohydrates and fat), achieved the highest percentage (65 percent) of one-year diet adherence of several popular diets, noting that “adherence level rather than diet type was the key determinant of clinical benefits.” A 2010 study in the Journal of Pediatrics found that after one year children receiving behavioral therapy maintained a body mass index that was 1.9 to 3.3 lower than children who did not. (BMI is a numerical height-weight relation in which 18.5 is held to be borderline underweight and 25 borderline overweight.) The Pediatrics report noted that “more limited evidence suggests that these improvements can be maintained over the 12 months after the end of treatments.” A 2010 study in Obesity found that continuing members of Take Off Pounds Sensibly (TOPS), a national, nonprofit behaviorally focused weight-loss organization, maintained a weight loss of 5 to 7 percent of their body weight for the three years of the investigation. The U.K.’s Medical Research Council last year declared that its own long-term study had shown that programs based on behavioral principles are more likely to help people take and keep the weight off than other approaches. (The study was funded by Weight Watchers, but without its participation.)

But Weight Watchers and other mass-market programs tend to fall short when it comes to enlisting a full range of behavioral techniques and customizing them to meet the varied needs of individuals. They cannot routinely provide individual counseling, adapt their advice to specific challenges, assess environmental factors in a member’s home, workplace or community, provide much outreach to members who do not come to meetings, or prevent their members from shooting for fast, dramatic, short-term weight loss or from restricting food groups. As a for-profit company, Weight Watchers sometimes even mildly panders to these self-defeating notions in its marketing. “Some people join us to drop 10 pounds for a high school reunion,” says Weight Watchers’s Miller-Kovach. “They achieve that goal, then stop coming.”

To close that gap, a number of researchers have turned their attention in recent years to improving, expanding and tailoring behavioral techniques, with encouraging results. For example, Michael Cameron, head of the graduate behavioral analysis department at Simmons College and a faculty member at Harvard Medical School, is now focusing his research on behavioral weight-loss techniques. He is one year into a four-person study—behavioral analysts generally do very small group or even single-subject studies to more closely tailor the intervention and observe individual effects—in which the subjects meet together with him via online videoconferencing for reinforcement, weigh themselves on scales that transmit results via wireless networks, and have their diets optimized to both reduce caloric density and address individual food preferences. Favorite foods are used as a reward for exercise. So far the subjects have lost between 8 and 20 percent of their body weight.

Matt Normand, a behavioral analyst at the University of the Pacific, has focused on finding ways to more precisely track subjects’ calorie intake and expenditure by, for example, collecting receipts for food purchases, providing food checklists to record what is eaten, and enlisting various types of pedometers and other devices for measuring physical activity. He then provides participants with daily detailed accounts of their calorie flow and in one published study showed three of four subjects reduced calorie intake to recommended levels. Richard Fleming, a researcher at the University of Massachusetts Medical School’s Shriver Center, has in Obesity looked at ways to encourage parents to steer their children to healthier choices. He has found, among other techniques, that showing parents in person what appropriate serving sizes of foods look like on plates is helpful. Another successful Fleming trick: letting children pick out a small treat at a food store—as long as they walk there. “Kids can really respond to that reward for being active,” he says.

Why are behavioral interventions effective? Laurette Dubé, a lifestyle psychology and marketing researcher at McGill University’s Faculty of Management, notes that our environment is currently one in which ubiquitous, sophisticated marketing efforts prey on our need for sensory gratification as well as our vulnerability to misinformation. In addition, the poor eating and exercise habits we observe in our friends, family and colleagues encourage us to follow suit. In essence, behavioral interventions seek to reconfigure this environment into one in which our needs for information, gratification and social encouragement are tapped to pull us toward healthy food and exercise choices rather than away from them. “When we are getting the right messages in enough ways, we have a better chance of resisting the urge to eat more than we need,” Dubé says.

Changing Policy
There is no one-size-fits-all solution, behavioral or otherwise, to the problem of obesity. But although behavioral interventions work best when they are customized to individuals, mass-market behavioral approaches such as Weight Watchers and TOPS are at least fairly effective. Why don’t more people lose weight with them? The main reason is that people simply do not sign up for them, often because would-be weight losers are chasing fad diets or supplements or have read that obesity is locked into our genes. Weight Watchers, by far the most popular behavioral weight-loss program, counts only 600,000 meeting-attending members in its ranks in North America. That means that fewer than one out of 100 obese people in the U.S. and about one out of 200 overweight people are part of a formal behavioral-modification program.

Public policy may be changing, however. The U.S. Surgeon General’s office and the CDC have both publicly lined up behind behavioral approaches as the main weapon in what is becoming a war on obesity. First Lady Michelle Obama’s high-profile Let’s Move campaign against childhood obesity consists almost entirely of behavioral weight-loss wisdom—that is, find ways to encourage children to eat less-calorie-dense foods, to become more active, and to enjoy doing it. The recent proposed ban of toys in Happy Meals in San Francisco suggests that more officials may be getting ready to pressure the food industry into easing up on contaminating the environment with what are essentially obesity-supportive marketing tactics. To make it easier and more tempting to buy healthier food in poorer, disproportionately over­weight communities, the White House has proposed subsidizing the costs of fruits and vegetables. Approaching the problem from the other direction, New York City Mayor Michael Bloomberg is among those who have advocated modifying food-assistance programs to restrict the purchase of high-sugar beverages, and last year Washington, D.C., enacted a 6 percent tax on sugary drinks. New York City has also offered vouchers for buying produce at farmers’ markets to low-income families and incentives to stores to offer healthier fare.

Some experts are trying to push the government to rewrite zoning and building codes to ensure that neighborhoods and buildings become friendlier to walkers, bikers and stair climbers. A 2009 study by researchers at Louisiana State University Medical School found that a mere 2.8 percent increase in a person’s stair usage alone would keep off almost a pound a year. “The correlation between activity levels and healthy weight is one of the best-established ones in all of obesity research,” says William M. Hartman, a psychologist and director of the behavioral program of the highly regarded Weight Management Program of the California Pacific Medical Center in San Francisco.

Increasing access to behavior therapy would help, too. Many overweight people might only need online behavioral monitoring, support and progress-sharing tools, which have proved moderately effective in studies. Others may need much more intensive, more personal interventions of the kind Cameron is developing. Given that obesity especially plagues the economically disadvantaged, fees for these programs may have to be heavily subsidized by the government and health care insurers. A weekly session with a behavioral therapist costing $50 would amount to $2,500 a year, or a bit more than a third of the $7,000 per year societal and medical costs of obesity—and the sessions might only be needed for a year or two to establish new, permanent eating and exercise habits, whereas the savings would continue on for a lifetime.

It is too soon to say whether the public will accept government efforts to push it toward healthier choices. In San Francisco, a community known to be especially friendly to public health initiatives, the plan to ban Happy Meals has provoked angry reactions, and Mayor Gavin Newsom vetoed it. Efforts by Let’s Move to bring healthier food to school cafeterias have been intensely criticized by some as overly intrusive. Even if these efforts are eventually fully implemented nationwide, there is no way of being sure they will significantly reduce obesity. The current rate of obesity is far beyond any ever seen before on the planet, and thus a large-scale solution will necessarily be an experiment in mass behavior change. But the research suggests that such a grand experiment would be our best shot at fixing obesity and that there is reason to be hopeful it will succeed. Given that more and more scientists, public policy experts and government officials seem eager to get it off the ground, we may well have early findings within this decade.