The prevalence of excess weight is increasing rapidly across the country: close to 65% of the U.S. adult population was recently estimated to be overweight or obese (1-2). According to data from the National Health and Nutrition Examination Survey (NHANES), the combined prevalence of overweight and obesity (body mass index [BMI] ≥25kg/m²) increased by nearly 40% between 1976–1980 and 1999–2000 (from 46% to 64.5%), and the prevalence of obesity (BMI ≥30kg/m²) increased by 110% (from 14.5% to 30.5%) (2).

Although the prevalence of obesity has increased among Americans of all ages, races, ethnicities, socioeconomic levels, and geographic areas (3-4), one of the largest increases has occurred among Hispanics: from 12% in 1991 to 21% in 1998 (5). Part of this increase in the prevalence of obesity among Hispanics may be attributable to changes in dietary habits, which have been well documented among Hispanics as a group, although few studies have been reported specifically on the dietary habits of U.S. Hispanics of Central American ancestry. The Hispanic Health and Nutrition Examination, for example, sampled only Mexican Americans, Cuban Americans, and Puerto Ricans, and NHANES III, conducted from 1989 to 1994, sampled only Mexican Americans (2).

Demographic indicators of low socioeconomic status (SES), including low educational attainment, unemployment, poverty, and (for women) number of children, have previously been associated with overweight and obesity among members of specific ethnic groups (6-9). Lack of health insurance coverage and restricted access to health care services, including services for the prevention, treatment, and management of conditions related to overweight and obesity, have also contributed to Hispanics' relatively poor health status. Approximately 32.4% of the 45 million uninsured people in the United States are Hispanic (10). Hispanics' efforts to acquire health insurance and health care have sometimes been compromised by language barriers and cultural practices and beliefs (11).

For immigrant populations, acculturation to U.S. norms can lead to the adoption of a more sedentary (westernized) lifestyle and, as a result, to excess weight and obesity (6,7,12,13). Acculturation occurs when members of one cultural group (usually a minority group) adopt the beliefs and behaviors of another group (usually the dominant group) (14). For the past 15 years, the prevalence of obesity among immigrants living in the United States has approached that of U.S.-born adults even though most minority immigrants in the United States are from countries where the prevalence of obesity is lower than in the United States (6).

Overweight and obesity are associated with significant health problems and financial burdens. In the United States, obesity was recently estimated to be responsible for almost 300,000 deaths each year and annual health care costs of $117 billion (1). In 2000, more than 17% of all deaths in the United States were attributable to overweight and obesity; only tobacco use accounted for more deaths (15). Overweight and obesity have also been linked to a variety of chronic diseases, including cardiovascular disease, type 2 diabetes, hypertension, stroke, dyslipidemia, osteoarthritis, breathing problems, some cancers, and depression (16).

Overweight and obesity are caused by an imbalance between the number of calories that people consume and the number of calories that they burn (17). According to the Centers for Disease Control and Prevention, poor diet and physical inactivity, both modifiable behaviors, are substantial contributors to deaths associated with being overweight (6). While factors such as genetics and aging may also increase people's risk of being overweight, in the United States the environment is believed to be influential in promoting energy intake and discouraging physical activity (17,18).

For this study, we analyzed data from the 2001 California Health Interview Survey (CHIS 2001) to examine how various social, cultural, and behavioral factors were related to overweight and obesity among the adult Hispanic population as a whole and the Mexican American and Central American populations specifically. The findings from this study can add to our understanding of how these factors may influence Mexican Americans' and Central Americans' response to obesity prevention interventions.

Our findings substantiate those of previous studies showing that Mexican American adults living in the United States have relatively high rates of overweight and obesity. For example, 1999–2002 data from NHANES showed that 73% of Mexican American adults were at least overweight and 33% were obese; they also showed that obesity rates had increased from 24% to 27% among Mexican American men and from 35% to 38% among Mexican American women during this period (24). Our findings, however, also include some disaggregated information on Central Americans, who do not routinely appear in the health literature, and highlight clear differences between Mexican Americans and Central Americans in how various factors affect their risk of being overweight or obese.

In all four ethnic subgroup/sex categories, increasing age was associated with an increased risk of being overweight or obese, at least through age 49. Education level was inversely associated with the risk of being overweight or obese for all Mexican American groups, though the high rate of obesity among Mexican Americans who did not complete high school was particularly compelling. Among Central Americans, those who were college graduates were somewhat surprisingly more likely to be overweight or obese than were those who did not have a college education. Using data from NHANES III, Zhang and Wang (25) found that overweight was more prevalent among women than among men; by age, most prevalent among adults aged 41–49; and among men more prevalent among those of high SES but among women more prevalent among those of low SES. Results from the San Antonio Heart Study (26)  showed that the prevalence of overweight was higher among Hispanics than among non-Hispanic whites and higher among women than men.

In our study, both Mexican American and Central American women with three children were more likely to be overweight than were those with none, while having four or more children was associated with obesity only among Mexican American women. The results of previous studies have similarly suggested a positive association between the number of children that women have and their risk of being overweight or obese (27-29).

We found that acculturation as indicated by U.S. residency of 15 years or more was a strong correlate of obesity for both Mexican and Central American men but not for women of either group. We also found that Mexican Americans, on average, had been in the United States longer than Central Americans. Previous research has indicated that level of acculturation may play an important role in the development of obesity within the Hispanic population, as immigrants follow the trend of native-born Americans toward more sedentary behavior and the consumption of more calorie-rich foods (30-32). Data from a cross-sectional survey of Latino men and women from a community sample indicated that acculturation was the strongest correlate of obesity (5), although other research findings also suggest that acculturation may be more complex than the definition we used and needs to be defined more broadly (33). We recommend that future studies of obesity risk and overall health in immigrant populations focus on how both are affected by the interplay of sociocultural and income changes (34).

We found that fair to poor self-reported health status was consistently associated with an increased risk of being overweight or obese. However, the correlation between access to care, as measured by having health insurance, and the risk of being overweight or obese varied substantially between Central and Mexican Americans. Mexican American men and women with health insurance were each more likely to be obese than those without, whereas Central American men without coverage (but not Central American women without coverage) were more likely to be overweight and more likely to be obese than were those with coverage. Further research will be needed to delineate the relationship between having health insurance and the risk of being overweight or obese in these two Hispanic subgroups.

Hispanics in general have self-reported comparatively poor access to health care services, which is usually associated with a lack of health insurance (11,34). Although the results of two studies have suggested that insurance status has no real effect on the quality of health care (30,35), the National Health Disparities Report, which offers a snapshot of the nation's progress on health care, showed that various health parameters, including insurance as a measure of access, were worse among Hispanics than among most other U.S. racial/ethnic groups (31). Furthermore, some of this disparity has been attributed to Hispanic men having particularly low rates of health insurance and health care access, which two recent studies have cited as being important factors in health outcomes (11,36). The findings from these studies suggest that although having health insurance may not ensure that people receive quality care, it at least makes accessing care easier. In addition, the health status and access to care of undocumented immigrant Hispanics are likely to be worse than those we reported among Hispanics who are here legally (11).

In analyzing health behaviors, we found that Central American men who reported binge drinking were less likely to be obese than those who did not. We also found that Mexican American men and women who did not take vitamins were more likely to be obese than those who did. Micronutrient deficiencies and poor dietary variety have been associated with high energy intake and BMI; and serum concentrations of certain vitamins such as A, D, E, and the carotenoids have been associated with diet, race, and obesity (37,38). Our findings thus support those of previous studies and suggest that greater emphasis should be placed on the role of diet and micronutrients in maintaining an optimal BMI, particularly among people such as binge drinkers, who are particularly vulnerable to dietary shortfalls.

Finally, we found a significant association between absence of physical activity and being overweight among Mexican American women. A substantial body of data has shown physical activity levels to be associated with body weight and body fatness (18,39). Two studies (40,41) have shown levels of physical activity to be lower among Hispanics than among non-Hispanic whites, and this lack of physical activity is a possible factor in the high rates of type 2 diabetes found among Hispanics, especially Mexican Americans (42). To increase levels of physical activity and exercise among particular Hispanic subgroups, health officials will need to examine barriers to and facilitators of such activity for each subgroup before planning strategies to enhance participation. And in planning strategies for women, they should also consider issues pertaining to body image and weight-related distress.

Overall, most of the factors we found associated with overweight or obesity have been reported in other studies; however, our study was notable in that it sampled a large number of Hispanics from California, where the majority of Mexican Americans and a substantial portion Central Americans in the United States reside. The large number of Mexican Americans in our study sample allowed us to estimate the prevalence of overweight and obesity and to identify the risk factors for excess weight in this population with considerable confidence, and the inclusion of Central Americans allowed us to present corresponding estimates for a segment of the U.S. Hispanic population that has been ignored in many studies and national surveys.

Because our analyses were based on cross-sectional data, significant associations with overweight or obesity should not be taken as proof of causation. Other limitations include incomplete dietary data on respondents' portion sizes and consumption of high-calorie foods such as sweets. Our study also did not address environmental factors that contribute to weight gain, such as a reliance on fast food outlets and convenience stores with limited dietary choices, and heavy marketing of calorie-dense foods (2,43,44). In addition, we calculated subjects' BMI on the basis of their self-reported height and weight, which may have led to the misclassification of some overweight or obese participants, since people who are overweight or obese may tend to underestimate their weight and overestimate their height (45). Although we used the normal BMI criteria for classifying people as overweight or obese, BMI calculations based on actual height and weight measurements rather than the self-reports of survey participants may have produced different results; however, the percentages of Mexican Americans aged 18 to 64 that we estimated to be obese using CHIS data were similar to corresponding estimates based on data from NHANES III, in which subjects' BMI was derived from clinical measurements of their height and weight (23% vs 20% for men; 25% vs 24% for women).

Because Hispanics are expected to constitute 25% of the U.S. population by 2050 (46), policymakers, community leaders and members, and Hispanic advocates must act now to reduce the striking health disparities between U.S. Hispanics and the overall U.S. population. Our findings show that a considerable proportion of Mexican Americans and Central Americans are at risk for adverse health outcomes because of their weight; however, they also show that rates of overweight and obesity in these two Hispanic subgroups vary, as do some of the factors associated with being overweight or obese. These differences suggest the need for weight-reduction interventions that target specific subgroups of Hispanics by country of origin, level of acculturation, and socioeconomic status; they also support previous recommendations that providers of health care information to Spanish-speaking populations consider factors such as their audience's cultural competency and language proficiency (43,47,48). Our finding that the percentage of Hispanics who are overweight or obese increases with acculturation also suggests that one approach to reducing rates of overweight and obesity and improving the overall health of Hispanics might be to encourage them to maintain their traditional dietary practices. However, whatever specific interventions are used to reduce the prevalence of overweight and obesity in Hispanic communities, the success of these intervention efforts will continue to depend on cooperation between community members and health care workers (5).