Foreign-born Hispanics lose their advantage in the fight against obesity; the role of
acculturation
Brenda Mendizabal, MS, MD; Alexandra C. Ehrlich, MPH; Matthew Oster, MD, MPH
Abstract
Childhood obesity continues to disproportionately affect Hispanic children compared to white
children. The reasons for this disparity remain unclear. The Hispanic health paradox has
previously proposed improved health outcomes amongst the Hispanic population. Acculturation,
however, has been shown to have a negative impact on long-term health among Hispanics. Our
objective was to determine the impact of acculturation on the development of overweight and
obesity amongst Hispanic children and adolescents in the U.S.
We analyzed cross-sectional examination and questionnaire data from the U.S. National Health
and Nutrition Examination Survey 2007-2010. Overweight and obesity were defined as BMI zscore > 85th and >95th percentile, respectively. Race/ethnicity was considered Hispanic, nonHispanic White, non-Hispanic Black, or other, based on self-report, and country of birth was
used as a measure of acculturation. We used multiple regression analyses to assess associations
of foreign-born, BMI z-score, age, sex, race/ethnicity, and socioeconomic status.
Among the 6,672 participants in this study, Hispanics comprised 21.2% of the overall sample
and 39% of them were overweight. Among all subjects, those born in the U.S. had a 1.5 increase
in the odds of being overweight, and a 1.7 increase in the odds of being obese compared to those
who were foreign-born (OR 1.5, 95% CI 1.1-2.0, p-value 0.01; OR 1.7, 95% CI 1.2-2.4, p-value
0.01). Hispanics born in the U.S. had similar findings, with a 1.3 increase in the odds of being
overweight compared to foreign-born Hispanics (OR 1.3, 95% CI 1.1-1.7, p-value 0.04).
However, this difference disappeared with increasing time in the U.S., with no difference after 5
years (test for trend: p<0.01 for overweight, p=0.048 for obesity).
In the U.S., Hispanic children are more likely than non-Hispanic whites to be overweight. Being
U.S. born may contribute to this disparity. Foreign-born Hispanic children appear to be
protected from negative health outcomes initially, as proposed by the Hispanic health paradox.
However, as these children become more acculturated in the U.S., their risk for overweight and
obesity matches that of U.S. born children, proposing acculturation as a major health risk factor.
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Introduction
The obesity epidemic has reached an all-time high, now affecting over twelve and a half million
children in the U.S.i This epidemic, however, is not affecting all children equally. Studies
continue to show the disproportionate effect overweight and obesity have on Hispanic children
and adolescents in the U.S.ii Hispanic children who are four to five years old have a higher
prevalence of overweight than those in any other racial or ethnic group.iii As the prevalence of
overweight and obesity amongst Hispanic children continues to rise, it is important to understand
the factors that contribute to this disparity; especially since the elevated risk of obesity has
previously not been explained by other socioeconomic factors in the past, such as maternal
education, household income, or food security.iv
For years there was belief in the Hispanic health paradox, whereby Hispanic immigrants were
proposed as being healthier than the U.S. born population.v In fact, perinatal studies have
consistently documented more favorable outcomes among Hispanic children as compared with
African American children.vi On the contrary, there have been recent concerns that acculturation
is a major contributor to the negative health outcomes seen amongst Hispanic children. It raises
the question of whether the positive health benefits seen with the Hispanic health paradox are
merely temporary, and if acculturation plays a bigger role than previously believed. Using data
from the US National Health and Nutrition Examination Survey (NHANES), we aimed to
determine the role of acculturation as a major risk factor for the differences in the rates of
overweight and obesity between U.S. born and foreign-born Hispanic children. We
hypothesized that there would be greater rates of overweight and obesity among U.S. born
Hispanic children and adolescents when compared to foreign-born Hispanic children, and
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therefore, acculturation would be considered a major risk factor for the development of
overweight and obesity.
Methods
Data Source
NHANES is a cross-sectional, complex, multistage probability sampling survey. It consists of an
in-person interview and physical examination, collecting data from self-reports, physical
markers, and laboratory specimens. It is designed to select participants representative of the
civilian, non-institutionalized U.S. population. The sample does not include persons residing in
nursing homes, members of the armed forces, institutionalized persons, or U.S. nationals living
abroad. NHANES oversamples selected populations to provide reliable estimates of minority
populations and relevant to this present study, including all Hispanics since 2007vii.
Study Population and Measurements
Using NHANES data from 2007-2010, we included all participants age two to nineteen who had
information from the Mobile Examination Center, which included the physical exam and
interview portion. We created BMI z-scores using individual BMI (kg/m2) from the medical
exam file. An individual was defined as being overweight if he/she had a BMI z-score >85th %ile and obese if he/she had a BMI z-score >95th %-ile. Through demographic and questionnaire
files, participants additionally reported other covariates of interest, including socio-demographic
characteristics such as gender, age, race/ethnicity, country of birth, and length of time in the U.S.
if they reported themselves as foreign-born. Country of birth was used as a measure of
acculturation in this study. Country of birth has previously been used in health research as a
substitute for migration and level of integration with the American culture, retrospectively.viii A
participant’s country of birth was categorized as either U.S. or foreign-born. Foreign-born
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individuals included those participants who answered as “born in Mexico” or “born elsewhere
than the United States.”
Statistical Analysis
All analyses were obtained using survey procedures available through SAS 9.3. To adjust for the
sampling methodology and obtain nationally representative results accounting for non-responses,
we calculated four year weights from the cycle sample weights provided by NHANES public
files. Descriptive statistics were calculated using proc surveymeans and proc surveyfreq
analyses, using weights for adequate error calculations. We used survey logistic multiple
regression analyses to assess associations of race/ethnicity and country of birth (U.S. born versus
foreign-born) with overweight status among children ages two to nineteen years, adjusting for
age, sex and socioeconomic status (ratio of income to poverty level).
Results
Participant Demographics
A total of 6,672 participants were included in our study. Sociodemographic characteristics are
demonstrated in Table 1. The mean age was 10.5 years old and the mean BMI among all
participants was 20.3. Overall, 35% of participants were overweight and 19% were obese.
Individuals identifying as Hispanic or Mexican-American comprised 21.2% of the sample, with
39% of this population being overweight. Overall, 6% of participants identified themselves as
foreign-born, with 2.5% living in the U.S. for less than 5 years, and 3.5% of them living in the
U.S. for greater than or equal to 5 years.
Primary Analysis
Amongst all racial/ethnic groups, non-Hispanic blacks and Hispanics had the highest rates of
both overweight and obesity. Hispanics, in particular, were 1.48 and 1.45 times more likely to
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be overweight or obese, respectively, compared to non-Hispanic whites regardless of age,
gender, or poverty ratio (overweight: OR 1.48, 95% CI 1.27-1.71, p-value <0.0001; obese: OR
1.45, 95% CI 1.19-1.77, p-value <0.0003). Additionally, among all subjects, those born in the
U.S. had a 1.5 increase in the odds of being overweight, and a 1.7 increase in the odds of being
obese compared to those who were foreign-born (overweight: OR 1.5, 95% CI 1.1-2.0, p-value
0.01; obese: OR 1.7, 95% CI 1.2-2.4, p-value 0.01).
Analyzing Hispanics separately, we found significant differences amongst U.S. born and foreignborn Hispanics, but these differences were dependent on the length of time spent in the U.S.
U.S. born Hispanic children and adolescents were significantly more likely to be overweight
compared to their foreign-born counterparts, adjusting for age, sex, and poverty ratio (OR 1.3,
95% CI 1.1-1.7, p-value 0.04). However, as Figure 1 shows, the differences in rates of
overweight and obesity between U.S. born and foreign-born Hispanics changed over time.
While foreign-born Hispanics had lower rates of overweight and obesity upon entry into the
U.S., these differences disappeared with increasing time in the U.S. (test for trend: p<0.01 for
overweight, p=0.048 for obesity).
Discussion
In this, the first large-scale study examining the effect of time in the U.S. on rates of overweight
and obesity among foreign-born Hispanics, we found that foreign-born Hispanics may initially
be protected from negative health outcomes, but that this protection disappears over time. As
hypothesized, acculturation is a major risk factor for the development of overweight and obesity
among Hispanic children and adolescents, despite differences in age, sex, and poverty level.
Acculturation has been known to be a very complex construct whereby there is simultaneous
maintenance and adaptation of cultural characteristics. Previous studies have proposed
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acculturation as a major risk factor for the development of overweight and obesity, with results
similar to those in this study. Wiley et al, for example, examined the relationship between BMI,
dietary intake, and maternal acculturation in mostly Puerto Rican children in the Hartford, CT
area. Approximately 200 Hispanic, 84% Puerto Rican, mother-child dyads were given surveys
on acculturation and dietary intake at an urgent care center where BMIs were obtained. They
found higher acculturation to the U.S. was associated with higher child BMI percentiles and
higher consumption of “non-core” (i.e. those not native to the country of origin) foods.ix
Similarly, amongst Hispanic adults, Kaplan et al. found long-term Hispanic immigrants (i.e.
those living in the U.S. for greater than or equal to 15 years) had experienced a nearly 4-fold
greater risk of obesity than recent immigrants, or those living in the U.S. for less than 5 years.
They hypothesized this higher risk of obesity as being associated with length of residence and
acculturation processes.x Sussner and colleagues used focus groups and in-depth interviews to
look at these acculturation processes a little closer. Mothers from focus groups and interviews
identified changes in dietary quality and intake, physical activity and rising sedentary behaviors.
They additionally described changes in eating practices/routines, breastfeeding, and cultural
beliefs about food, time pressures and lack of social support since immigrating as major
influences as factors of acculturation.xi
Despite seemingly irrefutable evidence that acculturation is a risk factor for the development of
negative health outcomes, there has been controversy in the past with some studies suggesting
the opposite. Ariza used a cross-sectional survey study design in two-inner city Chicago public
elementary schools to investigate acculturation and obesity amongst 250 five-to-six year old
Hispanic children. They unfortunately found similar prevalence of overweight children
regardless of mother’s birthplace, and they found no significant correlation between
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acculturation score and child weight-for-height percentile.xii Arredondo and colleagues studied
how parenting skills influenced a child’s risk for obesity. They found no clear positive
associations between children’s diets and acculturations, and actually found that less acculturated
Hispanic parents in the U.S. were more likely to encourage their children to eat more and “clean
their plates,” possibly contributing to higher rates of obesity among less acculturated familiesxiii
Some of these discrepancies may be contributed to small sample size, and possibly because
Hispanics all too often are grouped into one homogenous group. Studies rarely take into account
the different Hispanic subgroups, which may reveal different cultural backgrounds.
The Hispanic health paradox has been thought of as a protective factor for Hispanics as it relates
to health outcomes and has been used to explain the unexpected disconnect between well-known
socio-demographic risk factors and health outcomes in Hispanic individuals.xiv Although
foreign-born Hispanics who have lived in the U. S. for a short period of time remain somewhat
protected, as demonstrated in our current study, this does not hold true for very long. This study
demonstrates a greater risk of overweight and obesity for both U.S. born Hispanics and foreignborn Hispanics who lived in the U.S. for greater than or equal to 5 years. Although not a direct
contraindication to the Hispanic health paradox, it is evident through this study that the length of
time spent in the U.S. after they have immigrated is an important environmental factor that
contributes to the prevalence of obesity in this vulnerable population.
Some important limitations of the study to acknowledge include the use of the NHANES data
set. This is, of course, a cross-sectional study, and thus cannot make inferences about true
causality between acculturation and obesity among Hispanic children. Additionally, like many
other studies on this topic, we grouped Hispanics as a whole into one large group. As previously
mentioned, there may be differences among the different subsets of Hispanics and country of
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origin may play more of an important role than we anticipate. Unfortunately, the NHANES data
limits questions regarding race and ethnicity to Mexican American or Other Hispanic. We are
therefore unable to infer differences among the subsets of Hispanics. One final limitation to
mention is that we used country of origin as a measure of acculturation. Previous studies have
used primary language use, with this showing a stronger association with acculturation. Within
this population of children, many of which were very young, no preferred language was given,
and so we were unable to use this as a primary measure of acculturation.
As demonstrated by our study, acculturation is a major contributing factor to the development of
overweight and obesity in the Hispanic population. Overall, it is imperative we account for
acculturation status as it pertains to the obesity epidemic among Hispanic children, as this may
impact treatment strategies in the future. Acculturation among foreign-born Hispanics children
is complex, as they may be protected during the first few years of living in the U.S. We now
know that this does not persist. Future research is needed to determine what protective factors
exist, and what acculturation processes occur that contribute to the decline in health outcomes
among these children. As we continue to stride for greater impacts in obesity prevention and
treatment strategies, we must take acculturation into account.
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Table 1: Participant Demographics
Age
2-5 years
6-11 years
12-19 years
N
1771
2737
2164
%
22.2
38.4
39.4
Male
Female
3186
3486
48.6
51.4
Non-Hispanic White
Non-Hispanic Black
Hispanic or Mexican-American
Other
2177
1503
2584
408
57.5
14.3
20.8
7.5
U.S. born
Foreign-born, U.S. <5 years
Foreign-born, U.S. ≥ 5 years
6166
195
277
94
2.5
3.5
Sex
Race/Ethnicity
Acculturation
Figure 1:
100
90
80
70
Overweight or Obese
60
Obese
50
US Born Hispanic/MexicanAmerican Percent Overweight
or Obese
40
30
20
US Born Hispanic/MexicanAmerican Percent Obese
10
0
< 1 Yr
> 1 Yr to < 5 Yrs
> 5 Yrs
Figure 1: Percent overweight or obese and obese amongst foreign-born Hispanics and Mexican Americans
by time spent in the U.S. Solid and dotted lines represent U.S. born Hispanics and Mexican Americans who
are overweight or obese and obese respectively.
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