Major differences in prevalence of overweight according to
nationality in preschool children living in Germany:
determinants and public health implications
J Kuepper-Nybelen, A Lamerz, N Bruning, J Hebebrand, B Herpertz-Dahlmann, H Brenner
See end of article for
Dr H Brenner, Department
of Epidemiology, German
Centre for Research on
Ageing, Bergheimer Str.
20, 69115 Heidelberg,
Arch Dis Child 2005;90:359–363. doi: 10.1136/adc.2004.052423
Aims: To investigate the prevalence of overweight according to nationality in preschool children living in
Germany, and to establish the determinants responsible for differences in body mass index.
Methods: The study was performed within the context of the 2001/2002 obligatory health examination
before school entry in the city of Aachen, Germany. Of 2020 eligible children 1979 children were
recruited (participation rate: 98%). Children’s height and weight were measured using a standardised
protocol. The parents completed a standardised questionnaire on sociodemographic factors and possible
determinants of nutritional status. Being overweight was defined according to age and sex specific
reference values for German children as well as according to international reference values.
Results: The study population included 452 (22.9%) children with other than German nationality. Among
these children the prevalence of overweight was twice as high than among German children (14.8% v
7.2%). Prevalence of most known risk factors for overweight, such as low physical activity, high
consumption of soft drinks, and frequent visits to fast-food restaurants was higher in the children with other
nationalities than in the German children. Multivariate analyses revealed that most of the difference in
prevalence of obesity by nationality is explained by known risk factors of overweight, especially education
of mother and watching TV.
Conclusions: The apparent ethnic differences could be explained by two non-ethnic but socioeconomic
factors. In preventing overweight in children, there is the need to identify and deal with high risk
environments rather than high risk ethnic groups.
epidemic.1The incidence and prevalence of obesity in
children and adolescents are increasing in many countries
around the world2including countries in Europe.3German
preschool children have gained a higher body mass index
(BMI) during the last 30 years according to a recent study
conducted in the city of Aachen, which also revealed that
increasing BMI affected children in the upper weight range
more than those in the lower range.4It is known that obesity
in children persists into adulthood5 6and increases the risk of
obesity related morbidity later in life.7 8
Regarding obesity, there seems to be great variation by
ethnic groups both between and within populations. In the
United States, where obesity is particularly common, a large
variation in childhood obesity by ethnic groups has been
shown,9with rates generally highest for Hispanic and Native-
Estimates of the prevalence of overweight of children in
European countries suggest that prevalence is higher among
the southern countries of Europe.11However, pertinent data
comparing prevalences of overweight according to ethnic
groups within European countries, including Germany, are
Several factors have been discussed that may be contribut-
ing to different obesity prevalence rates in ethnic groups.
They include environmental factors such as high caloric food
supply and a rapid change from an active to a sedentary
lifestyle and socioeconomic factors. The role of the latter
appears to vary across countries with different development
levels. In developing countries children with higher socio-
economic status are more likely to be obese, whereas in
besity is considered to be the most prevalent nutri-
tional disease in developed countries, and it is widely
acknowledged that obesity has emerged as an
developed countries socioeconomic status is inversely related
to obesity.12Other contributing factors are race, which
remains an independent risk factor after controlling for
differences in socioeconomic status,13physical activity levels
which vary by ethnicity,14dietary patterns,15and factors
related to the home environment such as television watching
Within the last decade, many European countries have
faced high rates of immigration, particularly of young
families, and there is now a large diversity of national groups
among children living in many European countries. Recent
epidemiological studies on childhood obesity in Europe have
not included comparisons between children of different
nationalities living in the same country. However, with
regard to adequate and effective prevention programmes it is
necessary to identify the risk factors and to adapt measures
as much as possible. The aim of this study was to investigate
the prevalence of overweight of German children and
children of other nationalities living in Germany, and to
establish the determinants responsible for possible differ-
ences in BMI.
Study design and study population
All children born between 1 July 1995 and 30 June 1996, who
attended the 2001/2002 obligatory health examination before
school entry in the city of Aachen, Germany, and who were
accompanied by a parent with sufficient knowledge of
German, were enrolled in this cross-sectional study. The
study was conducted in cooperation with the Aachen Public
Health Service between December 2001 and July 2002 after
approval by the Ethics Board of the University of Aachen.
The children’s anthropometric data, including height and
weight, were measured according to a standardised protocol
as part of the routine examination conducted at the
prospective primary school of the children. Body weight in
underwear was measured to the nearest 0.1 kg and height to
the nearest 1 cm using a digital scale (Seca column scale 910
with telescopic measuring rod, Hamburg, Germany). Body
mass index (BMI) was calculated as weight (kg)/height (m2).
The age and sex specific BMI percentile ranks were calculated
by a German internet based reference program (www.
mybmi.de), which is based on pooled data from 17 epide-
miological studies in Germany, including anthropometric
data of 17 147 boys and 17 275 girls in the age range 0–18
years.17A BMI > the 90th centile was defined as being
overweight. Additionally, prevalence of overweight was
estimated according to the age and sex specific cut-off points
derived from international data as recommended by the
Childhood Obesity Working Group of the International
Obesity Task Force.18These cut-off points (boys: 17.5, 17.6,
17.7, and 17.9 kg/m2; girls: 17.2, 17.3, 17.5, and 17.8 kg/m2
for ages ,5.75 years, 5.75 to ,6.25 years, 6.25 to ,6.75 years,
and >6.75 years, respectively) are linked to the widely
accepted cut-off point for overweight of a BMI >25 kg/m2.
During the examination the parents were asked to
complete a standardised 42 item questionnaire, which
included questions on sociodemographic factors as well as
on several suggested determinants of nutritional status. The
screening questionnaire was presented in German; however,
one of our research assistants was always available at the
survey location and was able to explain unclear items to the
We first described the study participants with respect to basic
sociodemographic factors. The children were categorised in
German children and children with other nationalities
according to the nationality of their mothers in order to take
the cultural background of the mother into account, who is
the person with the closest contact to the child in most cases.
The nationality of the mother was strongly linked to the
country where the mother has predominantly lived before
age 18: more than 90% of German mothers, but less than 20%
of mothers with other nationality had predominantly grown
up in Germany. Hence, although no clear definition of
ethnicity of the children (which is rather difficult for
European countries) was available in this study, nationality
as defined here should closely reflect the ethnic background
in most cases. Next, the prevalence of overweight as well as
eating habits and various suggested risk factors for over-
weight were described according to nationality.
Furthermore, we used multiple logistic regression analyses
to assess to what extent differences in prevalence of
overweight (dependent variable) by nationality are explained
by the following known or suggested risk factors or protective
factors: mother’s and father’s school education classified
according to the German school system (,9 years, 9 years,
10–12 years, 13 years), watching TV on weekdays (,2 hours/
day, >2 hours/day), watching TV on weekends (,2 hours/
day, >2 hours/day), doing sports or playing outside ((16/
week, .16/week), consumption of sweets ((16/week, .16/
week), consumption of savoury snacks ((16/week, .16/
week), consumption of soft drinks ((16/week, .16/week),
visiting fast-food restaurants ((16/week, .16/week), BMI
of mother (,25 kg/m2, >25–,30 kg/m2, >30 kg/m2), and
BMI of father (,25 kg/m2, >25–,30 kg/m2, >30 kg/m2).
These variables were added one by one to the regression
model, and changes in odds ratios (ORs) for nationality by
inclusion of these covariates were recorded. The covariates
were entered into the model in the order of their impact on
the OR—that is, the variable which changed the OR for
nationality the most was entered first, and this algorithm was
repeated until none of the remaining covariates changed the
OR by more than 5%. Finally, a fully adjusted model was
calculated in which all mentioned risk factors were con-
sidered. All analyses were carried out with the SAS statistical
software package version 8.2.
Of the 2020 children who fulfilled the inclusion criteria, 1979
parents (98.0%) agreed to participate in the study. Overall, a
sample of 1974 children remained for the final analysis after
exclusion of one child without determination of anthropo-
metric measures and another four children without informa-
tion on the nationality of the mother.
Table 1 gives basic characteristics of the study population.
About half of the children were boys, and the majority were
6 years of age (78.9%). About one quarter of the children had
a nationality other than German. Most of them were Turkish
children (32.3%) or came from Eastern European countries
Table 2 presents the prevalence of overweight in German
and non-German children according to German and inter-
national reference values. Based on the German values, a
BMI >90th centile was seen in 7.2% of the German children,
but prevalence was more than twice as high (14.8%) in the
children with other nationality (p , 0.0001). There were no
differences in the prevalence of overweight due to sex,
neither among the German (p=0.85) nor among the non-
German children (p=0.49). Dividing the other children by
regions of origin, children from Turkey had the highest
prevalence of overweight (21.2%). In children from Southern
Europe, combining the countries Italy, Greece, Spain, and
Portugal, overweight was prevalent in 18.2% of the pre-
schoolers. Prevalences of overweight were generally higher
according to the international reference values, but variation
of overweight between nationalities was very similar for both
classification schemes. Therefore, further analyses regarding
variation of overweight by nationality were carried out using
the German reference values only.
Table 3 shows the prevalence of several factors known or
suggested to be associated with overweight. Children with
other nationality had less exercise and watched TV more
often than German children; 31.9% of parents of non-
German children compared to 8.6% of parents of German
Sociodemographic characteristics of the study
*Southern Europe=Greece, Italy, Portugal, Spain.
?Central Europe=Austria, Belgium, Denmark, France, Great Britain,
`Eastern Europe=Albania, Bosnia-Herzegovina, Bulgaria, Croatia,
Hungary, Kosowo, Macedonia, Moldavia, Poland, Romania, Russia,
Serbia, Ukraine, Yugoslavia.
360Kuepper-Nybelen, Lamerz, Bruning, et al
children reported their children watching TV for two hours
and more on weekdays. Also consumption of unhealthy food
like savoury snacks, soft drinks, and fast-food more often
than once a week was more prevalent in children of non-
German nationality. Furthermore, parents of non-German
children were more often overweight themselves and were
less educated than parents of German children.
Table 4 presents the analysis regarding the contribution of
suggested risk factors to the differences in prevalence of
overweight by nationality. In crude analysis children with
nationality other than German had a 2.23-fold odds to be
overweight compared to children of German nationality. This
association could mostly be explained by education of the
mother and by watching TV on weekdays. The OR for
nationality was reduced to 1.37 after inclusion of these two
covariates in the logistic regression model. The additional
consideration of other risk factors did not change the OR
substantially. After simultaneous inclusion of all considered
risk factors in the multivariate analysis, there remained a
moderate, statistically non-significant independent associa-
tion of nationality with overweight (OR 1.30, 95% CI 0.87 to
1.93). Additionally the same analysis was done dividing
defined by German and international cut-off points for overweight
Prevalence of overweight in German children and children with other nationality
Boys German children
Children with other nationality
Children with other nationality
Both German children
Children with other nationality
Children from Southern Europe
Children from Central Europe
Children from Eastern Europe
Children from other countries
*Cut-off point for overweight: BMI >90th centile.
?Cut-off point for overweight: defined to pass through BMI of 25 kg/m2at the age of 18.
children living in Germany
Prevalence of risk factors for overweight by nationality among preschool
German (n=1522)Other (n=452)
Doing sports or playing outside
Watching TV on weekdays
Watching TV on weekends
Consumption of sweets
Consumption of savoury snacks
Consumption of soft drinks
Visit to fast-food restaurants
BMI of mother
BMI of father
Education of mother
Education of father
39026.0 220 49.8
70 4.661 13.6
*p value from x2test (without adjustment for sex).
Prevalence of overweight in children361
children with other nationality into subgroups (data not
shown). For the Turkish children the crude odds to be
overweight was 3.46 (95% CI 2.23 to 5.38); however, this
association was again strongly reduced and no longer
statistically significant after full adjustment (OR 1.66, 95%
CI 0.97 to 2.83).
Our analyses of the prevalence of overweight by nationality
among 1974 preschool children attending the 2001/2002
obligatory health examination before school entry in the city
of Aachen, Germany, indicated a higher prevalence of known
risk factors for obesity and a two times higher prevalence of
overweight in children with other than German nationality
than in German children. In Turkish children, the largest
group of foreign children, the prevalence of overweight was
three times higher than in German children. Multivariate
analyses revealed that most of the difference in prevalence of
obesity by nationality is explained by known risk factors of
overweight, especially education of mother and watching TV,
whereas there remained only a moderate, statistically non-
significant association of nationality with overweight after
control for these risk factors.
The proportion of people with other than German
nationality living in Germany in 2001 was 8.9%. However,
the proportion of children with other than German nation-
ality was higher (children 0–5 years of age: 9.7%; children
6–14 years of age: 10.5%),19and there is substantial regional
variation with a much higher proportion of foreign children
in the Western part than in the Eastern part of Germany. In
this study 22.9% of the subjects were children with other
than German nationality. Most of them held Turkish
nationality (32.3%) or came from Eastern European countries
(21.9%). This distribution is in accordance to corresponding
national figures.19Furthermore, the city of Aachen is a typical
German city with respect to the population’s age distribution
and indicators of socioeconomic status, such as unemploy-
ment rates and the proportion of inhabitants receiving
welfare payments.20Particular strengths of this study were
the very large number of participating children and the very
high participation rate, making selection bias very unlikely.
Our findings of significant differences in prevalence of
overweight between different ethnic groups within a country
are consistent with those of US studies, generally considering
ethnic groups.9 10 21 22Only a few European studies on BMI in
children examined different ethnic groups within a country.
Based on data from 1983, Caucasian and Afro-Caribbean
children in Britain were found to have a similar weight-for-
height index, but it was higher than that for Asian children in
younger age groups.23These patterns have been confirmed in
later investigations from 199324and 1999.25In France,
children with Maghrebian origin were found to have a
higher prevalence of obesity.26Brussaard and colleagues,27
who investigated migrants in the Netherlands, figured out a
higher risk of overweight for Turkish and Moroccan children
aged 4–15 years than for Dutch children, based on data from
1992/1993. In a recent study from Germany the frequency of
overweight in non-German boys was 1.9 times higher and in
non-German girls 1.5 times higher than in German boys
and girls, respectively.28However, none of these studies
established determinants responsible for the prevalence
In our investigation education of the mother emerged to be
the factor contributing most to the different prevalence of
overweight between German and other children. In parti-
cular, the proportion of mothers with very low levels of
school education was much higher among children with a
nationality other than German than among German children.
Low maternal education may be associated with an insuffi-
cient knowledge of the risk factors for obesity like an
unhealthy diet with a high energy intake from fat and from
sugar sweetened soft drinks and a sedentary lifestyle. Low
education also often goes along with low socioeconomic
status. An inverse relation between socioeconomic status of
the parents and obesity in children has been reported in
studies from developed countries.29 30In the study of the
migrants in the Netherlands the lower socioeconomic
position of the migrant groups partly explained their less
favourable health status, but a study among Turkish people
indicated that their health status was also lower than that of
Dutch people of comparable socioeconomic status.27
Time spent watching TV, which can be considered an
indirect indicator of (lack of) physical activity, was the other
main factor contributing to the difference between over-
weight prevalence of German and other children. Physical
inactivity is a risk factor for obesity in children.31 32Time
spent with television viewing has been associated with body
fatness in children of various ethnicities in some,33–35but not
all studies.36Although time spent with television viewing is
related to indicators of low socioeconomic status, such as low
maternal education and low family income,37it further
contributed to explain ethnic differences in overweight in
our study even after consideration of maternal education.
One limitation of our study is that, as in other studies
comparing children from various nationalities, anthropo-
metric data from migrant children were compared to
reference data for German children, based on pooled data
of 17 studies conducted in various regions of Germany. No
reference data for children with other nationality living in
Germany are available yet, nor were reference data for
Turkish children (the biggest group of children with other
than German nationality in our study population) from
Turkey published in the literature. However, when using
international reference values for overweight in children,18
the differences in prevalence of overweight between children
of the considered nationalities essentially stayed the same,
even though the absolute prevalence was higher in all
subgroups. Another intriguing question that could not be
assessed with adequate power in this study, despite its large
size, was that of potential interactions between nationality
(according to German reference values) by nationality
Contribution of suggested risk factors to differences in prevalence of overweight
Included variables into the regression modeln OR*
Crude OR for other nationality
OR for other nationality after adjustment for education of mother
After additional adjustment for watching TV on weekdays
After full adjustment?
1.62 to 3.09
1.06 to 2.17
0.95 to 1.99
0.87 to 1.93
*Reference category: German nationality.
?Adjustment for education of mother and education of father, watching TV on weekdays and watching TV on
weekends, doing sports or playing outside, consumption of sweets, consumption of savoury snacks, consumption of
soft drinks, visiting fast-food restaurants, BMI of mother, and BMI of father.
362 Kuepper-Nybelen, Lamerz, Bruning, et al
and lifestyle covariates—that is, potential variations in the
role of lifestyle factors between nationalities. Such interac-
tions, which might be of clear relevance for public health
measures, should be specifically addressed in future, even
In conclusion, our results clearly indicate that prevalence
of overweight among children varies greatly between
children of different nationalities and countries of origin
living in the same country. These apparent ethnic differences
can be explained by two non-ethnic but socioeconomic
factors. Therefore, in order to prevent overweight in children,
it is important to identify and deal with high risk environ-
ments rather than high risk ethnic groups. There is the need
to change mothers’ beliefs about diet, or about fat children
being healthy children, and to inform especially low educated
mothers about healthy lifestyle. Furthermore, there is the
need to understand why children watch television a lot and
to offer alternatives to TV as a form of low cost childcare. Due
to the early onset of obesity at the age of 6, prevention efforts
should start prior to school entrance. In Germany every child
is offered nine routine paediatric check-ups between birth
and the age of 6. These check-ups, which are attended by
many children and their parents, might provide an excellent
opportunity for paediatricians to address the weight devel-
opment of the child and to consult the parents regarding
prevention of overweight among their children.
We would like to thank the staff of the Aachen Public Health Service,
Sandra Schaefer, Christine Schell, Martina Selzner, and Christine
Wehle for their support and cooperation in field work of this study.
J Kuepper-Nybelen, H Brenner, Department of Epidemiology, German
Centre for Research on Ageing, Heidelberg, Germany
A Lamerz, N Bruning, B Herpertz-Dahlmann, Department of Child and
Adolescent Psychiatry, Technical University of Aachen, Germany
J Hebebrand, Clinical Research Group, Department of Child and
Adolescent Psychiatry, Philipps University of Marburg, Germany
Funding: This study was funded by the German Society for the
Advancement of Scientific Research (DFG grants HE 1809/5-1 and BR
1704/4-1) and by the START-Program of the Medical Faculty, RWTH
Competing interests: none declared
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What this study adds
N Determinants responsible for prevalence differences
are non-ethnic but socioeconomic factors
What is already known on this topic
N Prevalences of overweight differ by ethnic groups
Prevalence of overweight in children 363