International Journal of Obesity (2006) 30, 684–690 & 2006 Nature Publishing Group All rights reserved 0307-0565/06 $30.00 www.nature.com/ijo ORIGINAL ARTICLE Ethnic differences in obesity among immigrants from developing countries, in Oslo, Norway

BN Kumar1, HE Meyer1,2, M Wandel3, I Dalen4 and G Holmboe-Ottesen1

1Section of Preventive Medicine and Epidemiology, Department of Community Medicine and General Practice, University of Oslo, Oslo, Norway; 2Norwegian Institute of Public Health, Oslo, Norway; 3Department of Nutrition, University of Oslo, Oslo, Norway and 4Institute of Basic Medical Sciences, Department of Statistics, University of Oslo, Oslo, Norway

Objectives: To compare ethnic and gender differences in generalized and central obesity and to investigate whether these differences persisted after adjusting for socio-demographic and lifestyle factors. Design: In 2002, the population-based cross-sectional, Oslo Immigrant Health study was conducted. Subjects: A total of 7890 Oslo residents, born between 1942 and 1971 in Turkey, Iran, Pakistan, Sri Lanka and Vietnam, were invited and 3019 attended. Measurements: Participants completed a health questionnaire and attended a clinical screening that included height, weight, waist and hip measurements. Results: Generalized obesity (BMIX30 kg/m2) was greatest among women from Turkey (51.0%) and least among men from Vietnam (2.7%). The highest proportions of central obesity (waist hip ratio (WHR)X0.85) were observed among women from Sri Lanka (54.3%) and Pakistan (52.4%). For any given value of BMI, Sri Lankans and Pakistanis had higher WHR compared to the other groups. Despite a high mean BMI, Turkish men (27.9 kg/m2) and women (30.7 kg/m2) did not have a corresponding high WHR. Ethnic differences in BMI, waist circumference and WHR persisted despite adjusting for socio-demographic and lifestyle factors. Conclusion: We found large differences in generalized and central obesity between immigrant groups from developing countries. Our data find high proportions of overweight and obese subjects from Pakistan and Turkey, but low proportions among those from Vietnam. Subjects from Sri Lanka and Pakistan had the highest WHR for any given value of BMI. Our findings, in light of the burgeoning obesity epidemic, warrant close monitoring of these groups. International Journal of Obesity (2006) 30, 684–690. doi:10.1038/sj.ijo.0803051; published online 30 August 2005

Keywords: ethnic minorities; immigrants; body mass index; waist circumference; waist hip ratio

Introduction lifestyle factors have been observed.4,5 The close linkage of obesity to type 2 diabetes and associations with a wide The global obesity epidemic, marked by alarming propor- spectrum of morbidities make it one of the most important tions in affluent countries and increasing numbers in some avoidable risk factors.6 developing countries, raises several concerns.1,2 This burden While BMI is widely accepted as the measure of obesity, of obesity is not shared equally by all segments of society and Deurenberg-Yap et al. among others have highlighted that varies by ethnicity.3 some ethnic groups have higher body fat percentage (BF%) at Obesity exhibits both genetic and environmental associa- relatively lower BMI.7,8 Current literature supports evidence tions, suggesting individual susceptibility that interacts with that immigrants are no exception to the obesity epidemic9 in adverse environmental conditions. While the exact causes of the USA and Europe.10 However, European studies to date obesity remain to be fully elucidated, associations with have been limited to few selected immigrant groups. demographic, socio-cultural, biological, behavioural and Immigration to Norway from developing countries, largest groups being from the Indian subcontinent and the Middle East,11 dates back only 30 years. Studies from countries of origin 12 Correspondence: Dr BN Kumar, Section of Preventive Medicine and show fairly low levels of generalized and central obesity. Epidemiology, Department of Community Medicine and General Practice, However, to date, obesity among immigrants from developing University of Oslo, PO Box 1130, Oslo N-0318, Norway. countries in Norway has not been described in any detail. E-mail: [email protected] Received 18 January 2005; revised 17 June 2005; accepted 5 July 2005; The objectives of this paper are to analyse whether there published online 30 August 2005 are ethnic and gender differences in generalized and central Ethnic differences in obesity among immigrants BN Kumar et al 685 obesity in five major immigrant groups, and furthermore to Questionnaire determine if these differences persist after adjusting for The main questionnaire covered a wide range of issues, socio-demographic and lifestyle factors. including general health status, self-reported disease, risk factors, as well as socio-demographic factors. The question- naires were based on questions previously used for ethnic Subjects and methods Norwegians, and were not validated for immigrants. The original questionnaires along with official English transla- The population-based, cross-sectional, Oslo Immigrant tions can be found at the following website: http:// Health Study was conducted by the Norwegian Institute of www.fhi.no/tema/helseundersokelse/oslo/index.html Public Health and the University of Oslo in 2002. Oslo residents, born in Pakistan, Sri Lanka, Turkey, Iran and Vietnam, were invited to attend. This study followed the Variables Oslo Health Study (HUBRO 2000–2001), described in detail The Norwegian Registry of Vital Statistics provided informa- elsewhere (www.fhi.no), and both studies followed the same tion on the age, gender, country of birth and residential protocol. The Norwegian Data Inspectorate approved the address. Ethnicity was determined on the basis of country of study and it has been cleared by the Regional Committee for birth from this register. A cross-check with Statistics Norway Medical Research Ethics. (SSB) registers confirmed that in 99.8% of cases the country of birth was identical to their ‘country of origin’. Self-reported continuous variables included years of Sample education, years lived in Oslo and number of children. From the 2001 population register, 7972 individuals (born Respondents were asked about their smoking status; 1942–1971) were eligible for participation, excluding those and their responses were categorized as: (1) yes, now (current who had already participated in HUBRO (800 persons born smoker), (2) yes, earlier (previous smoker) and (3) never in 1940, 1941, 1955, 1960 and 1970). Since 11 individuals (nonsmoker). had died and 72 had emigrated prior to the invitation, 7890 Self-reported leisure-time physical activity was assessed by were eligible for participation but only 7607 were reached by a four-graded measure (inactive to very active) shown to mail. Of the 7607 reached by mail, 3019 attended a clinical predict the mortality risk in both genders. Responses screening, gave their written consent and met the criteria of included: (1) ‘reading, watching television or other seden- inclusion (completion of at least one question in either of tary activities’ (inactive/sedentary); (2) walking, cycling the questionnaires), attaining a final response rate of 39.7%. or moving at least four times per week; (3) taking part Participation rates according to country of birth are as in physical exercise/sport or heavy gardening; (4) hard follows: Turkey 32.7%, Sri Lanka 50.9%, Iran 38.8%, Pakistan exercise or participation in competitive sports regularly 31.7% and Vietnam 39.5%, respectively. The nonresponder (very active). pattern among these groups was similar to that observed in the preceding Oslo Health Study, described in detail else- 13 where. Data analysis Data were analysed using the SPSS package 11.0. We report Data collection gender-specific, age-adjusted descriptive statistics for BMI, WHR and waist circumference (WC). Means were compared Two weeks prior to the clinical screening the questionnaire, by analysis of variance (ANOVA) and proportions by w2 tests. consent and information brochures and their appropriate Linear regression analysis, stratified by gender, explored translations were sent to participants. A single reminder was associations between indices of obesity and ethnicity, sent to nonresponders of the first invitation. Screenings, adjusting for age, education, number of years lived in Oslo, held at three local district stations, offered additional smoking, number of children and physical activity. assistance of fieldworkers fluent in the five immigrant languages. Results Anthropometry Body weight (in kg, one decimal) and height (in cm, one Sample characteristics decimal) were measured with an electronic Height and Background characteristics (Table 1) showed significant Weight Scale, with the participants wearing light clothing differences in age, with the Sri Lankans being the youngest without shoes. BMI (kg/m2) was calculated based on weight and Pakistanis the oldest. Iranians were significantly more and height. Both waist and hip were measured with a educated compared with all ethnic groups, the only excep- measuring tape of steel. Waist and hip circumference were tion being Sri Lankan women. Subjects from Turkey had the used to calculate the waist hip ratio (WHR), using the least education compared to all groups. Subjects from formula waist (cm)/hip circumference (cm). Pakistan had the longest length of stay in Oslo compared

International Journal of Obesity Ethnic differences in obesity among immigrants BN Kumar et al 686 Table 1 Background characteristics of adult immigrants from developing countries. Oslo Immigrant Health Study 2002

Turkey Iran Pakistan Sri Lanka Vietnam

Men (n ¼ 1679) (n ¼ 228) (n ¼ 359) (n ¼ 244) (n ¼ 603) (n ¼ 245) Age* 42.9 (41.9–43.9) 41.7 (41.1–42.4) 45.3 (44.3–46.4) 40.1 (39.7–40.6) 44.1 (43.1–45.1) Years of education* 9.8 (9.1–10.4) 14.8 (14.4–15.2) 11.5 (11.0–12.0) 13.0 (12.7–13.3) 11.6 (11.0–12.2) Years lived in Oslo* 16.1 (15.0–17.2) 9.2 (8.5–9.8) 20.5 (19.3–21.7) 9.9 (9.3–10.4) 13.3 (12.5–14.1) Proportion sedentary 51.7 (44.9–58.6) 46.7 (41.4–52.1) 58.3 (51.7–65.0) 51.5 (47.1–55.8) 55.0 (48.4–61.6) Proportion current smokers* 57.3 (51.3–63.4) 40.5 (35.7–45.2) 37.0 (31.0–42.9) 18.8 (14.8–22.7) 35.1 (29.3–41.0)

Women (n ¼ 1320) (n ¼ 196) (n ¼ 239) (n ¼ 196) (n ¼ 398) (n ¼ 291) Age* 41.1 (40.1–42.1) 41.7 (40.8–42.7) 43.9 (42.8–45.1) 39.5 (38.9–40.2) 43.5 (42.7–44.4) Years of education* 7.0 (6.3–7.8) 13.0 (12.4–13.7) 8.4 (7.7–9.2) 12.4 (12.0–12.7) 10.3 (9.8–10.9) Years lived in Oslo* 14.6 (13.6–15.6) 8.3 (7.7–8.9) 15.5 (14.5–16.5) 8.0 (7.6–8.5) 11.7 (10.8–12.6) Number of children* 2.9 (2.6–3.2) 2.2 (2.0–2.5) 3.5 (3.3–3.8) 2.1 (2.0–2.3) 2.7 (2.4–2.9) Proportion sedentary 61.4 (54.0–68.8) 48.8 (42.1–55.5) 61.8 (54.3–69.2) 54.1 (48.8–59.5) 56.4 (50.4–62.5) Proportion current smokers* 26.6 (22.5–30.8) 24.6 (20.9–28.3) 4.7 (0.4–9.0) 0 3.3 (0.1–6.6)

*Po0.001 – ANOVA for means and w2 test for proportions. All proportions are percentages (CI) and all other variables are means (CI).

to those from Sri Lanka. Pakistani women had the highest persisted. These factors, including age, accounted for 14.6% parity compared to all ethnic groups. Over 45% of the (BMI), 22.6% (WHR) and 22.3% (WC) of the ethnic respondents were sedentary, the greatest proportion being differences among men. In the case of women after among Pakistanis. Smoking was least reported among Sri adjusting, in addition to the other factors, number of Lankans and most reported among the Turks. children, ethnic differences persisted for BMI and WC between the Vietnamese and other groups, but only for Sri Lanka and Pakistan for WHR. These factors, including age, Anthropometric characteristics accounted for 27.9% (BMI), 18.7% (WHR) and 30.2% (WC) After adjusting for age, Vietnamese men and women had the of the ethnic differences. lowest mean height, whereas Turkish men and women had the highest mean weight (Table 2). BMI increased by age in all groups, except for the Pakistanis (Figure 1). After Relationship between the indices of obesity adjusting for age, the Vietnamese had the lowest BMI, After adjusting for age, positive associations between BMI whereas the Turks had the highest BMI for both genders and WHR were observed in all groups (Figure 2). For any (Table 2). All ethnic groups with the exception of Vietnam given value of BMI, the mean value of WHR was higher in had a lower mean BMI for men than women. Mean WC was subjects from Sri Lanka and Pakistan compared to other the greatest among Pakistani men and women. However, groups (Figure 2). Despite having the highest BMI, Turks did mean WHR was highest among Pakistani and Sri Lankan not have corresponding highest values for WHR. Ethnic men and women. differences followed a fairly similar pattern for WC though differences were attenuated (Figure 3).

Prevalence of obesity A greater proportion of women were obese (BMIX30 kg/m2) Discussion than men. Twice as many women from Turkey, Pakistan and Sri Lanka were obese compared to their men. The highest Our study has shown that immigrants in Oslo are no prevalence of obesity was among Turkish women (51.0%) exception to the onslaught of the obesity epidemic. General- and least among Vietnamese men (2.7%). Nearly 80% of ized obesity was most frequent among the Turks, with one Pakistanis and over 60% of Sri Lankans were found to have a out of two Turkish women having a BMIX30 kg/m2. BMIX25 kg/m2. Central obesity measured by WHR was However, central obesity was most frequent among the highest for Pakistani women (55.6%). Gender differences in Pakistanis and Sri Lankans. For any given value of BMI, the WHR were greatest among the Sri Lankan men and women WHR was considerably higher among Sri Lankans and (8.6 and 51.3%). Pakistanis compared to the other groups. Ethnic differences in BMI and WHR persisted despite adjusting for age, known socio-demographic, biological and lifestyle factors. Indices of obesity and associated factors For the first time in Norway, we have been able to study Despite adjustments for education, physical activity and and explore associations between actual anthropometric smoking, the ethnic difference in BMI, WHR and WC measurements and determinants of obesity among immi- between Vietnamese men and other ethnic groups (Table 3) grants, from a considerable population-based sample (3000).

International Journal of Obesity Ethnic differences in obesity among immigrants BN Kumar et al 687 Table 2 Age-adjusted anthropometric characteristics and age-adjusted obesity prevalence of adult immigrants

Turkey Iran Pakistan Sri Lanka Vietnam

Men (n ¼ 228) (n ¼ 359) (n ¼ 244) (n ¼ 603) (n ¼ 245) Height and weight Height in centimeters (mean (CI)) 170.9 (170.1–171.7) 171.6 (170.9–172.2) 170.2 (169.5–171.0) 167.7 (167.2–168.2) 164.4 (163.7–165.2) Weight in kilograms (mean (CI)) 81.2 (79.8–82.6) 78.0 (76.9–79.1) 79.4 (78.0–80.8) 72.1 (71.3–73.1) 65.3 (63.6–66.6)

Body Mass Index (BMI) Mean (CI) 27.9 (27.5–28.4) 26.6 (26.3–27.0) 27.5 (27.1–27.9) 25.8 (25.5–26.1) 24.2 (23.8–24.7) Prevalence of obesity (X30) 25.2 (20.9–29.5) 13.5 (10.1–17.0) 22.0 (17.8–26.2) 9.1 (6.5–11.8) 2.7 (1.0–6.9) Prevalence of overweight (X25) 79.8 (73.8–85.9) 71.2 (66.4–76.0) 77.1 (71.2–83.0) 58.6 (54.9–62.3) 40.2 (34.3–46.0)

Waist circumference (WC) Mean (CI) 93.0 (91.8–94.2) 89.3 (88.4–90.3) 93.6 (92.4–94.7) 89.0 (88.2–89.7) 80.2 (79.1–81.4) Prevalence of obesity (X102 cm) 17.2 (13.2–21.3) 9.4 (6.2–12.7) 26.4 (22.4–30.3) 10.1 (7.6–12.6) 0.0

Waist hip ratio (WHR) Means (CI) 0.91 (0.90–0.92) 0.90 (0.89–0.90) 0.93 (0.92–0.94) 0.93 (0.91–0.93) 0.87 (0.87–0.88) Prevalence of obesity (X1.00) 10.4 (6.8–14.0) 3.9 (1.1–6.8) 19.6 (16.1–23.29 10.2 (7.9–12.5) 1.8 (0–5.3)

Women (n ¼ 196) (n ¼ 239) (n ¼ 196) (n ¼ 398) (n ¼ 291) Height and weight Height in centimetres (mean (CI)) 156.9 (156.0–157.9) 157.0 (156.1–157.8) 157.3 (156.3–158.2) 155.4 (154.7–156.1) 153.2 (152.5–154.6) Weight in kilograms (mean (CI)) 75.2 (73.6–76.7) 65.3 (63.9–66.7) 72.3 (70.6–73.8) 64.8 (63.7–65.8) 54.4 (53.1–55.7)

Body mass index (BMI) Mean (CI) 30.7 (30.1–31.3) 26.5 (25.9–27.0) 29.3 (28.7–29.9) 27.0 (26.6–27.4) 23.2 (22.7–23.7) Prevalence of obesity (BMIX30) 51.0 (45.5–56.6) 20.2 (15.2–25.2) 39.8 (34.2–45.4) 20.9 (16.9–24.8) 3.1 (0–7.6) Prevalence of overweight (X25) 83.7 (77.6–89.9) 58.4 (52.9–64.0) 80.4 (74.2–86.6) 69.2 (64.8–73.5) 24.3 (19.2–29.3)

Waist circumference Mean (CI) 88.1 (86.7–89.5) 80.2 (78.9–81.4) 89.4 (88.0–90.8) 84.2 (83.2–85.1) 72.7 (71.6–73.9) Prevalence of obesity (X88 cm) 46.6 (40.8–52.5) 19.9 (14.7–25.2) 56.7 (50.9–62.6) 31.6 (27.5–35.8) 3.3 (0–8.1)

Waist hip ratio Mean (CI) 0.82 (0.81–0.83) 0.80 (0.79–0.81) 0.85 (0.84–0.86) 0.85 (0.84–0.86) 0.80 (0.79–0.81) Prevalence of obesity (X0.85) 33.0 (26.6–39.3) 23.1 (17.4–28.9) 52.4 (46.0–58.9) 54.3 (49.8–58.9) 21.4 (16.1–26.7)

Men Women 32.0 36.0

34.0 30.0 32.0

30.0 28.0 Ethnic Group Ethnic group

Tyrkia 28.0 Tyrkia

26.0 Sri Lanka 26.0 Sri Lanka

Iran Iran Mean Body Mass Index

Mean Body Mass Index 24.0 24.0 Pakistan Pakistan 22.0

Vietnam Vietnam 22.0 20.0 31-35 36-40 41-45 46-50 51-55 56-60 31-35 36-40 41-45 46-50 51-55 56-60 Age in groups Age in groups

Figure 1 Mean BMI of adults from five ethnic groups (Oslo Immigrant Health Study, Norway).

The low participation rate (39.7%) cannot rule out possible accessing South Asian communities is difficult, and is a self-selection. However, other researchers also report low barrier to research.14 attendance rates among marginalized groups, such as While one should be cautious in generalizing our findings immigrants in large population surveys. In particular, to the entire population, it is unlikely that the large

International Journal of Obesity Ethnic differences in obesity among immigrants BN Kumar et al 688 Table 3 Age- and multivariate-adjusted differencesa in BMI. WHR and WC between Vietnamese and other Immigrant groups

BMI diff. in kg/m2 (95% CI) WHR diff. in WHR (95% CI) WC diff. in centimetres (95% CI)

n Model 1 Model 2 Model 1 Model 2 Model 1 Model 2

Men Turkey 228 3.7 (3.1–4.3)* 3.5 (2.8–4.1)* 0.05 (0.04–0.06)* 0.05 (0.03–0.06)* 12.7 (11.1–14.4)* 12.6 (10.9–14.5)* Iran 358 2.4 (1.9–2.9)* 2.6 (2.0–3.2)* 0.03 (0.02–0.04)* 0.03 (0.02–0.04)* 9.0 (7.6–10.6)* 9.7 (8.2–11.5)* Pakistan 243 3.3 (2.7–3.8)* 3.3 (2.6–3.9)* 0.07 (0.06–0.08)* 0.07 (0.06–0.08)* 13.3 (11.7–14.1)* 13.5 (11.7–15.3)* Sri Lanka 603 1.6 (1.1–2.1)* 1.2 (0.6–1.8)* 0.06 (0.05–0.07)* 0.06 (0.05–0.07)* 8.7 (7.3–10.1)* 8.1 (6.5–9.7)* R2 (%) 11.9 14.6 21.5 22.6 20.6 22.3

Womenb Turkey 132 3.9 (3.1–4.7)* 6.8 (5.8–7.7)* 0.02 (0.00–0.03) 0.01 (À0.01–0.02) 14.2 (12.1–16.3)* 13.2 (11.0–15.5)* Iran 182 6.4 (5.4–7.3)* 3.6 (2.7–4.5)* 0.00 (À0.02–0.01) 0.01 (À0.01–0.02) 6.5 (4.6–8.4)* 7.8 (5.8–9.8)* Pakistan 110 3.9 (3.1–4.7)* 6.3 (5.3–7.3)* 0.04 (0.03–0.06)* 0.04 (0.02–0.05)* 16.0 (13.8–18.2)* 15.5 (13.3–17.7)* Sri Lanka 240 2.9 (2.0–3.7)* 4.2 (3.4–5.0)* 0.05 (0.04–0.06)* 0.06 (0.04–0.07)* 11.3 (9.4–13.1)* 11.6 (9.8–13.4)* R2 (%) 25.7 27.9 14.4 18.7 29.6 30.2

aValues in the other ethnic groups minus values for the Vietnamese. bNumber of children adjusted for in Model 2 for women only. *Po0.001 for differences between ethnic groups. Model 1: adjusted for age. Model 2: adjusted for age, education, physical inactivity, years lived in Oslo and current smoker. Note: Due to missing data on some variables in the fully adjusted models, n might be lower than in Table 2.

Men Women 1.00 0.92

0.98 0.90

0.96 0.88

0.94 0.86 Ethnic Group Ethnic Groups 0.92 0.84 Tyrkia Tyrkia 0.90 0.82 Sri Lanka Sri Lanka 0.88 0.80 Iran Iran 0.86 0.78 Estimated Marginal Mean WHR Pakistan Estimated Marginal Mean WHR Pakistan 0.84 0.76 Vietnam 0.82 0.74 Vietnam < 25 kg/m2 25-26.9 27-29.9 >= 30kg/m2 < 25 kg/m2 25-26.9 27-29.9 >= 30kg/m2

BMI in groups BMI in groups

Figure 2 Association of WHR and BMI among adults from five ethnic groups (Oslo Immigrant Health Study, Norway).

Men Women 110.0 100.0

105.0 95.0

100.0 90.0

Ethnic groups Ethnic Group 95.0 85.0 Tyrkia Tyrkia 90.0 80.0 Sri Lanka Sri Lanka

85.0 75.0 Waist Circumference Iran Iran Waist Circumference Estimated Marginal Mean Estimated marginal Mean

80.0 Pakistan 70.0 Pakistan

Vietnam Vietnam 75.0 65.0 < 25 kg/m2 25-26.9 27-29.9 >= 30kg/m2 < 25 kg/m2 25-26.9 27-29.9 >= 30kg/m2 BMI in groups BMI in groups

Figure 3 Association of WC and BMI among adults from five ethnic groups (Oslo Immigrant Health Study, Norway).

International Journal of Obesity Ethnic differences in obesity among immigrants BN Kumar et al 689 differences in obesity can be merely attributed to bias. the home country is often lost as education is not recognized Differences in prevalence of obesity between the Turks and by the host country. Immigrants from Pakistan and Turkey the Vietnamese are so great that it is nearly inconceivable originate mainly from rural areas, have lower levels of that they can be explained by selection bias. When education than other groups and are more obese. comparing associations between the indices of obesity and However, Sri Lankans, despite being younger, their short risk factors between groups, selection bias will be less than stay in Norway, higher education, low parity and lower when assessing prevalence estimates or population means BMI show higher WHR for the same BMI, indicating a more of risk factors.15 A comprehensive analysis of the nonatten- complex interplay of these factors. Others have discussed dance in the Oslo Health Study (2000–2001, that preceded the impact of socio-demographic factors in more detail, our study with the same protocol and similar dropout both concerning a possible increase in socio-economic problem) showed that age, education, income and gender gradient with time after migration, and the complexity of (women) were positively associated with attendance, and using SEP variables across ethnic groups being in different this also applied to non-Western immigrants in addition stages of transition in the European pattern of health to the Norwegians. However, their analysis concluded that inequalities.25 prevalence estimates were robust even in light of the Greater proportions of women were found to be over- considerable non-attendance.13 weight and obese compared to men, except for the Norway’s previously homogenous population has evolved Vietnamese. Immigrant women26 might be shielded from to a multicultural society that needs to examine ethnic Western societal norms and their associations with body health inequalities. Few studies have investigated groups image could differ in being more comfortable with extra like the Vietnamese, Iranians and Turks in comparison to kilograms. However, our data, being cross-sectional and the South Asians. Age and gender differences of the ethnic quantitative, limit such inferences and these underlying groups reflect the historical perspectives of migration; processes must be pursued. Pakistanis came here first and are the oldest. Our data are All immigrant groups were sedentary, notwithstan- also unique with regard to the most susceptible groups from ding the methodological limitations in assessing physical South Asia. Previous studies have identified intra-ethnic activity correctly in population-based surveys. Validity subgroup differences as a limitation to inferences of data problems of questionnaire data are greater in immi- obtained, due to the heterogeneity of risk factors.16 In our grants given the language problems, different conceptual study, the majority of immigrants from Pakistan (Punjabi) content, relevance and cultural norms about leisure time and Sri Lanka (Tamil) originate from one major ethnic group physical activity. However, for immigrants living in a and therefore intra-ethnic differences have been consider- cold northern Western country, outdoor physical activity ably reduced.17 remains challenging. The prevalence of obesity (BMIX30 kg/m2) among Discussing the socio-cultural adaptation, including issues Pakistani women (39.8%) is four times higher than such as integration, is beyond the scope of this study. Norwegian Women (11.6%).18 Immigrant women from deve- However, it is clear that the differences between the ethnic loping countries might be more traditional with regard groups in their socio-demographic characteristics and their to parity, physical activity, smoking and employment migration history indicate that this adaptation varies by compared to Norwegian women. The anthropometric means ethnicity. This is also confirmed by comparison with the (BMI, WHR and WC) among the Pakistanis are identical ethnic Norwegian population, where differences are greatest to the Riste et al.’s19 findings from Manchester in an urban with Pakistanis and Turks, but not as great with Iranians and but much smaller sample. Nevertheless, the mean BMI of Sri Lankans. Pakistani women (29.3 kg/m2) in our study is much higher In summary, we found large differences in generalized and than in a study from Pakistan (21.9 kg/m2).12 A study from central obesity between immigrant groups from developing Turkey reported lower prevalence of obesity (39.3%)20 than countries that add to the existing public health challenges. our sample. Diversity in obesity patterns between and within ethnic If the recently21,22 proposed WHO definitions23 are groups despite similarities in the physical environment has applied, an overwhelmingly large majority of the Pakistani been documented. However, data constraints limit any men (77.1%) and women (80.4%) are obese (BMI425 kg/m2), inferences to gene–environmental interactions. Pathways and 78.2% are overweight (BMI423 kg/m2). While BMI between socio-demographic factors associated with obesity, cutoffs underestimate BF% in these groups, WHR has shown particularly the directional effects of these relationships, the strongest association with diabetes across the ethnic need further investigation. The high prevalence of central groups, confirming the limitation of using the BMI for this adiposity in the South Asians identifies an obvious need for a purpose.24 long-term strategy of early prevention, particularly among Ethnic differences in BMI persisted after controlling for young women. Minorities are often at cross-roads, and tailor- socio-demographic and lifestyle factors. Migration is synony- made strategies that are culturally sensitive need to be mous with change of living conditions, status in life and designed, developed and evaluated to halt this burgeoning lifestyle. During migration, professional status enjoyed in epidemic.

International Journal of Obesity Ethnic differences in obesity among immigrants BN Kumar et al 690 Acknowledgements 10 Brussaard JH, van Erp-Baart MA, Brants HA, Hulshof KF, Lowik MR. Nutrition and health among migrants in The Netherlands. Public Health Nutr 2001; 4: 659–664. We thank Kathleen Glenday and Zumin Shi for assistance, 11 Kumar B, Holmboe-Ottesen G, Lien N, Wandel M. Ethnic Anne Johanne Søgaard and Aage Tverdal for valuable differences in body mass index and associated factors of comments. The data collection was conducted as part of adolescents from minorities in Oslo, Norway: a cross-sectional the Oslo Immigrant Health Study 2002 in collaboration with study. Public Health Nutr 2004; 7: 999–1008. 12 Jafar TH, Levey AS, White FM, Gul A, Jessani S, Khan AQ et al. the Norwegian Institute of Public Health. BNK, HM, GHO Ethnic differences and determinants of diabetes and central obesity and MW contributed to the conception and design of the among South Asians of Pakistan. Diabet Med 2004; 21: 716–723. study. BNK, HM and ID analysed the data and all authors 13 Sogaard AJ, Selmer R, Bjertness E, Thelle D. The Oslo Health contributed to the interpretation of the data. BNK drafted Study: the impact of self-selection in a large, population-based survey. Int J Equity Health 2004; 3:3. the article and HW, MW, GHO and ID commented upon and 14 Rankin J, Bhopal R. Understanding of heart disease and diabetes revised the drafts. All authors gave their approval to the final in a South Asian community: cross-sectional study testing the version submitted for publication. The Oslo Immigrant ‘snowball’ sample method. Public Health 2001; 115: 253–260. Health Study was funded by the Norwegian Institute of 15 Bhopal RS. Concepts of Epidemiology: An Integrated Introduction to the Ideas, Theories, Principles, and Methods of Epidemiology. Oxford: Public Health and University of Oslo. 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