Community approaches to obesity treatment and prevention.

PL02-03

Recent increases in population obesity have been dramatic. Rates have more than doubled in the last two or three decades, marking a sharp upturn in historical trends in body weight in this country. As a result, two-thirds of U.S. adults are now considered overweight, and one-third are clinically obese. Although obesity is not equally distributed across different groups in our society, rates of obesity increase have been very similar in men, women, the elderly, and children. They have also been similar across different ethnic groups and social classes. Obesity has long been recognized to have both environmental and biological components. People who live in obesity-prone environments, generally affluent societies in which individuals have ample access to food and limited requirements for physical activity, are much more likely to be obese than those in environments less prone to obesity. Meanwhile, in both obesity-prone and nonobesity-prone environments, there is a strong biological link to obesity. Genetic influences have been estimated to account for half or more of individual variations in body weight in stable environments. Because recent changes in obesity have been so widespread and have occurred so quickly, the causes of these recent shifts are thought to be almost certainly the result of changes in the environment in which we live rather than changes in underlying biological forces. Exactly what aspects of our environment are the strongest contributors to changing obesity rates and how to change those environmental aspects are now the subject of intensive study by public health researchers interested in the obesity problem. The prevailing cultural belief in the United States is that body weight and obesity are the result of individual choices of behavior and, therefore, that the responsibility for obesity ultimately lies in the individual. Following this line of reason, it is generally believed that given the will, and adequate knowledge about how to change energy balance, most people could and would successfully control their weight. This cultural belief is not supported particularly well by scientific data. Most people who are overweight or obese recognize that they are heavier than they should be, most report that they would like to change, and most report that they are actively trying to do something about it. On any given day, roughly 50% of women and 33% of men report that they are doing something to actively try to control their weight. Although there is clear and well-documented evidence that some people who have had significant weight problems in the past have been successful in losing weight and keeping it off over long periods of time, for the vast majority of Americans, these weight control efforts have not been effective, thus continuing increases in population obesity. Nevertheless, the belief that exercise of personal self-control is the key to obesity management persists. The history of public health efforts to deal with the obesity issues from a public health perspective have also to date been driven, for the most part, by the belief in individual responsibility. The public health community has provided educational materials about body weight standards and about the relationship between eating and activity patterns and weight for several decades. These public health messages have been heard. Most people are knowledgeable about actuarial weight norms that apply to themselves. They are also generally knowledgeable about the energy content of food, for example, that high-fat animal products have more calories than fruits and vegetables. The most targeted forms of health education related to obesity are intensive counseling programs generally targeted at highly motivated, obese individuals. These education programs are relatively costly in time and effort. They have also been shown to have significant benefits for controlling body weight as well as the health consequences associated with body weight, although to date still falling short of desired rates of clinical effectiveness. For the most part, public health education, which has been distributed more broadly to the general population, has had much weaker effects than intensive education experiences. Indeed, it has proved difficult to demonstrate that any large-scale public health education efforts focused on obesity have been successful. Three efforts from our group at the University of Minnesota are exemplary, one in worksites, one in public health departments, and one in the healthcare delivery system. All three of these programs engage large numbers of people, all were successful in delivering nutritional messages that resulted either in improved knowledge of nutritional principals related to weight control and/or short-term beneficial changes in body weight. None, however, were able to demonstrate a measurable effect on the mean population body weight or obesity prevalence over periods of as long as one to two years. It has been tempting for some to argue that nutrition education efforts at a public health level are unable to have effects on behaviors related to obesity. We, however, believe such a conclusion is decidedly premature. We note, for example, that the public health message to reduce the intake of fats, and particularly animal fats, in the interest of promoting heart health, has been repeated consistently in many, many different ways for roughly 30 years and, not coincidentally, the fat intake in the U.S. has dropped by nearly 25% over that time. There is clearly more work that needs to be done to improve public health nutrition education related to obesity. One of the themes of our research group at the University of Minnesota over the last several years has been on this topic of public health messages. We have noted that some of the current nutrition education messages being propagated in connection with weight control by the public health community are likely to be ineffective. For example, "eat a variety of foods" is a standard public health education message from the U.S.D.A. Eating a variety of foods is a good message for ensuring nutritional adequacy. However, considerable research has shown that giving people a variety of foods to eat actually increases how much they eat, rather than decreasing it. We have also noted that at least one behavior quite strongly related to body weight and successful body weight control is not on the list of weight control recommendations in most public health nutrition promotions. This is regular monitoring of body weight. We are currently in the process of trying to develop a method for testing the effectiveness of different public health recommendations about weight control that are readily understood and acted upon and would have a demonstrably beneficial effect on population body weight. As noted earlier, environmental influences are thought to be especially important to secular trends in body weight; and one of the newest and most exciting areas of public health research in obesity is studying the extent to which direct manipulation of environmental factors can influence energy balance and body weight. Two areas in which our group in Minnesota has made specific contributions are in the effects of food cost on food selection and the effects of portion size on food consumption. We have examined the cost question in several studies with adults and with children, in cafeterias, and in vending machines. We have found a very consistent effect that changing the relative price of lower and higher energy-density food items dramatically alters purchase and presumably consumption patterns in the direction of healthier choices. We have also shown is a naturalistic study in free living adults that chronic exposure to large portion sizes increases usual energy intake and body weight. We are in the process of examining other issues as well, including breakfast eating, soft drink availability, and television viewing. Our most comprehensive effort in this area is an ongoing study called the HealthWorks Study, in which we are attempting to show that modifying prices, portion sizes, calorie content, and price of foods sold in work environments can result in lower energy intake at work that is not compensated for at home, and that translates into lower rates of weight gain with time. Similar efforts are being attempted by other investigators for children in school settings. Overall, our research group believes that the problem of population obesity is one that is understandable and reversible. To achieve this goal, we believe in the importance of broad societal involvement in managing the obesity epidemic and that multiple sectors of society will need to be involved in its solution.