Over the past two decades, there has been an alarming, unprecedented increase in childhood and adolescent obesity and at-risk-of obesity1 that has reached epidemic proportions. This increase has raised worldwide awareness and concern, particularly regarding the link between obesity and serious, chronic health conditions like diabetes, cardiovascular disease, hyperlipidemia, and others. The ultimate solution for reversing obesity requires maintaining energy balance and a healthy lifestyle; such a solution implies the development and implementation of specific, feasible, and efficient strategies and interventions defined through political, social, and cultural contexts specific for each country.
The Institute of Medicine (IOM) report Preventing Childhood Obesity: Health in the Balance (2005) found that among U.S. children, those of Hispanic origin, especially Mexican–American children, have the highest rates of obesity. Moreover, the obesity epidemic has been recognized in Mexico as well, where the public health community is paying increased attention to survey data indicating the growing obesity rates among children, youth, and adults. These findings, as well as the recognition of the unique context of the Mexican–American population in the United States
and the many similarities shared between the United States and Mexico, served as the basis for the initial discussions that resulted in this workshop.
Since the 1500s Mexican Americans have lived in what is now the southwestern United States and have maintained a continuing cultural and commercial exchange with Mexico. In fact, Mexicans continue to immigrate to the United States in unprecedented numbers. As they integrate in American society, they maintain their culture but also begin a process of acculturation, that is, they adopt many social norms and habits of the United States, including those related to diet and exercise; the consequences of acculturation in obesity prevalence are intriguing and still unclear.
Although, as already mentioned, solutions to prevent obesity should be feasible within the specific context of each country, the substantial and ongoing interchange of people and culture between the United States and Mexico necessitates an obesity prevention approach that recognizes the common social, cultural, and economic factors that contribute to childhood obesity in both countries. With this in mind, the IOM, with the Instituto Nacional de la Salud Pública (INSP) and supported by Kaiser Permanente, sponsored a joint U.S.–Mexico workshop that involved researchers, public health officials, industry leaders, and policy makers from both sides of the border. The primary objective of the workshop was to explore the potential for a U.S.–Mexico binational obesity prevention strategy by considering the perspectives and experiences of various stakeholders—governments, research institutions, industry, non-governmental organizations, and communities. Other objectives included assessing similarities and differences in the prevention of obesity in Mexican and Mexican–American children, sharing policy and program experiences, and identifying data and information gaps. This workshop summary focuses on the nature of childhood obesity, its magnitude and distribution, current and future policies and programs, and data needs. This summary should not be perceived as a series of recommendations reached by consensus but rather as a recapitulation of the discussions of speakers, working groups, and individual participants.
As background for the workshop, two papers were commissioned. The first paper, “Preventing Obesity in Mexican Children and Adolescents,” reviews the factors that contribute to the high obesity prevalence in Mexican children and adolescents, provides an overview of current obesity intervention programs, and proposes actions to prevent the epidemic. A second paper, “Preventing Obesity in Mexican–American Children and Adolescents,” addresses similar topics from a U.S. perspective.
OBESITY PREVALENCE AND ASSOCIATED FACTORS IN PEOPLE OF MEXICAN ORIGIN
Preventing Childhood Obesity: Health in the Balance (IOM, 2005) included an ecological model of the obesity problem and recommendations for action to all stakeholders. In the United States, CDC data demonstrated an alarming growth in obesity prevalence—among U.S. children and adolescents the rate tripled from approximately 5 percent to about 16 percent within the last 40 years. In Mexico, the data available from the National Nutrition Surveys show an increase of more than 30 percent from the 1988 to the 1999 survey in at-risk for obesity and obese Mexican children 2–4 years old. The 1999 survey indicates a high prevalence (16 percent) of obesity and at-risk of obesity among Mexican children, occurring in all regions, rural and urban areas, and in both girls and boys ages 2–17 years. At substantially higher levels, the obesity and at-risk for obesity prevalence among Mexican–American boys 2–11 years of age is about 38 percent. The epidemiological data presented show the existence of an obesity epidemic in Mexico with similar characteristics to the one in the United States.
This continued increase in prevalence makes obesity a problem of epidemic proportions, with a behavior that is comparable to the characteristics of infectious diseases. The negative implications of this rising trend in obesity for the economy and health on both sides of the border call for an urgent prevention strategy on all fronts.
Many factors associated with the risk of obesity are complex, including psychosocial, dietary, and physical activity factors, which ultimately are related to energy balance—the fundamental issue underlying the epidemic. As an example, changes in the diets are occurring in people on both sides of the border. Data presented show that instead of selecting fruits and vegetables in their diets, Mexicans as well as Mexican Americans are choosing more high-energy, less-nutritious foods. In Mexico, this might be related to cost, urbanization, changes in family structures, or other social factors. In the United States, on the other hand, the process of acculturation to the U.S. social rules and habits might be a contributor to the increasing obesity prevalence. Differences in the nature and occurrence of these nutritional transitions may explain one notable difference between the United States and Mexico—the relationship between socioeconomic status (SES) and the prevalence of obesity. In Mexico, a higher SES is associated with a higher prevalence of obesity, whereas the opposite relationship prevails in the United States. The relationships between obesity and SES in both countries might be simply explained by a difference in the progression of the epidemic in both countries that is, dietary changes experienced in both countries at different times, rather than a reflection of differences in dietary risk factors.
On the other side of the equation, data from physical activity tendencies call to the need for changes in this area. Data point to a low level of physical activity during and after school and a concurrent increasing trend in screen-viewing activities among children and youth in Mexico and the United States. This increase in sedentary activities might be spurred by a combination of factors related to safety concerns, lack of resources and time in schools, expense of activities, or other factors. In addition, having and enjoying appliances like televisions, computers, and cars provide a certain social status, therefore, supporting the hypothesis that a high SES might be causing a more obesigenic lifestyle.
Other cultural factors that are unique to the Hispanic population and define Mexicans on both sides of the border include the perception that being plump is equated with being at a healthy weight, and adherence to values that favor family needs over personal ones.
RESEARCH AND INFORMATION GAPS
Critical information gaps that thwart progress in obesity prevention among children and youth still remain and include the following two main themes: (1) risk factors leading to childhood obesity, particularly those related to behavioral patterns, along with strategies for interventions and implementations, and (2) design and implementation of studies to evaluate the efficacy of interventions and programs. Concerted efforts need to be directed towards solution-oriented research—research designs that lead directly to policy or practice changes that also include an evaluation component—in various areas; industry participation was seen as a necessity in translating research findings into effective interventions and programs.
Identifying Risk Factors and Developing Interventions and Implementation Strategies
What interventions and strategies will be effective in obesity prevention among Mexican–American and Mexican children? How should interventions be implemented? What specific intervention designs and testing are needed? Understanding behavioral factors through conducting experimental behavioral research on motivation and eating behaviors is critical to develop interventions that will result in long-term food and physical activity attitude changes. For example, searching for incentives to moderate the negative effects of acculturation and of adherence to certain values is an important focus of behavioral research. Another element of consumer behavior essential to designing effective interventions is that which derives from analysis of consumer responses to voluntary industry changes (e.g., new products and packaging). The industry could assist greatly in this en-
deavor by finding a mechanism for sharing marketing data; this is an area that was identified by individual participants as a current challenge.
To further assist in the design of randomized control trials on behavioral studies, researchers could conduct feasibility studies or pilot studies to test intervention strategies and identify potential barriers and facilitators of behavioral changes; this approach will help design and test appropriate intervention strategies before the more costly randomized control trials.
Information on other obesity-linked risk factors is scarce, so interventions are developed based on suggested associations. Therefore, there is a need to collect more data on obesity risk factors so that recommendations on interventions are based on sufficient evidence. For example, research on the effects of dietary content, eating patterns, physical activity and inactivity levels, and patterns leading to obesity prevention and weight control in already obese children could continue to be investigated so that a clearer picture of the factors and relationships among them can emerge. Once there is more evidence supporting the association between specific risk factors and obesity then a much broader testing of these interventions can be conducted in real-life scenarios.
Evaluating Interventions and Programs
An important aspect of reversing the obesity epidemic through interventions is evaluating programs that already have been implemented, internationally as well as locally. Researchers could gain important knowledge from those experiences and apply that knowledge to the development of new or improved strategies.
Much of the workshop participants’ discussion focused on the importance of conducting studies for evaluating macro level interventions (e.g., evaluation of governmental policies and actions such as food and nutrition regulations, taxations, trade policies, urban planning policies, dietary and physical activity guidelines, or other current public health initiatives).
OBESITY PREVENTION SOLUTIONS
Participants conveyed the urgency of the situation and that, despite the dearth of data available to indisputably link risk factors to childhood obesity, key players have a responsibility to develop and implement strategies to prevent childhood obesity based on the best available evidence.
Role of Various Sectors
In general, the majority of participants found that the main premise for an obesity prevention strategy is that the causes of obesity follow an eco-
logic causal model, and therefore the strategy to mitigate the epidemic should be multilevel, multisectorial, and multidisciplinary. Some participants suggested that a cost-effectiveness analysis of the obesity epidemic is critical in helping decision makers prioritize resource allocation for health programs. As mentioned previously, interventions will need to be based on the best available evidence. If possible, using information from data on evaluation of the efficacy of interventions could be used as an important component of decision making.
Several workshop participants presented their perspectives and experiences on the role of the community, schools, industry, and government in implementing efficient prevention measures (see highlights in Box S-1). Discussions also highlighted differences in the countries’ social and political systems and culture that could result in variations in implementation strategies.
Among the different perspectives presented, the issue of industry self-regulation versus government regulation to restrict food industry activities directed to children (e.g., marketing) was controversial. Ultimately, the group felt that industry self-regulation and government regulation both should be considered. The unifying theme in the group was that collaboration among sectors and disciplines is a crucial element of obesity prevention programs.
Next Steps Suggested by Working Groups and Individual Participants
Participants identified several barriers that are unique to the social and political context of each country. Ideas were discussed to overcome those barriers, and one major suggestion by Working Group III was the establishment of a government-led Mexican National Obesity Prevention Task Force paralleled to a joint U.S.–Mexico collaboration. Activities that could be the responsibility of this Mexican task force that were discussed by individual participants during the plenary are in Box S-2. Working Group III also proposed the creation of a U.S.–Mexico Obesity Prevention Task Force to initiate a collaboration to prevent obesity among children of Mexican heritage. Potential elements of such a collaboration are included in Box S-3 as summarized by Working Group III and discussed by individual participants in the plenary session. According to Working Group III, the responsibilities of the U.S.–Mexico Task Force would be the following:
Develop a strategy to prevent obesity.
Promote an obesity agenda with a specific timeline and responsibilities.
Promote policies and norms that will allow environmental modifications in schools, worksites, cities, and other venues.
Develop an educational strategy.
The Role of Public and Private Sectors in Preventing Obesity
The following are perspectives on the role of various sectors in preventing obesity as viewed by panelists from Mexico and the United States.
Community (U.S. perspective)
In Mexico, a sector that represents consumers’ interests does not exist, and efforts in developing prevention strategies that involve community participation should be pursued by empowering the communities and encouraging advocacy activities.
Schools (Mexican perspective)
Industry (U.S. and Mexican Perspective)
Government (U.S. and Mexican Perspective)
Mexican National Obesity Prevention Task Force
Participants in Working Group III listed several elements for a Mexican National Obesity Prevention Task Force. These were further expanded by individual participants and include:
U.S.–Mexico Joint Obesity Prevention Task Force
Participants in Working Group III listed several elements for a U.S.– Mexico Obesity Prevention Task Force and include the following: