Study characteristics & samples
All of the studies were published in the 1990s and 2000s, and all were conducted in the US. Eight studies utilised cross-sectional designs, while one was longitudinal (see Table 2). Of the studies reviewed, participant mean age was 41 years (SD = 15), and the male: female ratio across all studies was 32:68. The focus of the articles included was limited to immigrant and refugee resident populations, and thus, temporary residents were not represented in any of the studied populations. Study sample ethnicity included, Mexican-Americans [45, 46, 50, 51], Hmong (Thailand and Laos) US residents ; Korean-Americans , Puerto-Rican Americans [48, 51], and Soviet-American women . Six studies used BDM-scales to measure acculturation [45, 46, 49, 50, 52, 53] and three studies used UDM-scales [47, 48, 51]. Two studies used self-report measures for the BMI measure [46, 52].
Of the nine studies reviewed, seven reported overall positive associations between the degree of acculturation and body weight variables [45–50, 52]. The conclusions drawn from these studies generally complemented one another. Three studies [50, 51, 53] found negative associations between higher degree of acculturation and obesity in women. Lee et al.  found no significant relationship between acculturation and obesity in their female sub-sample, while more acculturated males recorded higher BMI.
In their study on US-born and Mexico-born Mexican-American adults living in the US, Barcenas et al.  indicated significant differences in the relationships between acculturation level and BMI, gender, and birthplace. In Mexican-born participants longer residency in the US was associated with higher BMI. Women residing in the US for more than 15 years recorded a mean BMI of 2.38 kg/m2 (β (adjusted) =2.12, 95% CI, 1.53-2.72, p < .0001) higher than those who had lived in the US for less than five years. Similarly, men living in the US for more than 15 years recorded an average BMI of 1.10 kg/m2 (β (adjusted) = 1.47, 95% CI, 0.59-2.34, p < .001) higher than residents of less than five years. Furthermore, the risk of obesity in men and women with a low degree of acculturation increased with every additional year of residence in the US by 2% (OR = 1.02, 95% CI, 1.00-1.03) and 1% (OR = 1.01, 95% CI, 1.01-1.02) respectively. For highly acculturated men and women the increase in risk was 4% (OR = 1.04, 95%CI, 1.01-1.07) and 3% (OR = 1.03, 95% CI, 1.00-1.05) respectively. In US-born Mexican-Americans, high acculturation and birthplace accounted for 6% and 25% of risk of obesity in men and women respectively.
These general findings of positive correlations between obesity and acculturation in Mexican-Americans, were further supported in the study by Ahluwalia et al.,  where comparable general associations between the degree of acculturation and BMI were established. Further, Khan et al.  found that 2nd and 3rd generation Mexican-Americans had higher BMIs than 1st generation migrants.
A similar study was conducted by Hazuda et al.  who established a more ambiguous and complex relationship between acculturation and obesity in Mexican-Americans. In this study, overweight was assessed using BMI, sub scapular-to-triceps skin-fold thickness (SUBTR) ratio, and waist-to-hip ratio (WHR). Both acculturation and socio-economic status (SES) were associated with anthropometry measurements. Specifically, low SES was associated with a high WHR (p < .001), and high scores on the ‘family attitude’ subscale of acculturation was associated with a high SUBTR-ratio (p < 0.01). Among females, low SES was associated with high BMI, SUBTR-ratio and WHR (p < .01 – p < .001), but, interestingly, high scores on the ‘functional integration’ acculturation subscale were associated with lower BMI and SUBTR-ratios (p < .01 – p < .0001). This apparently protective effect for Mexican-American women was also evident in Khan et al. , where higher acculturation was associated with lower BMI for Mexican-American women (β = −.56, p < .01) but not for males nor either gender in the other ethnicities examined (Puerto Rican and Cuban).
Other studies examined the impact of acculturation on health factors such as smoking, physical activity, fat intake, and BMI, and have included other ethnicities with similar results. For example, Bertera et al.  found that acculturation was positively associated with obesity in Salvadoran immigrants in the US, accounting (in combination with other variables such as gender and SES) for 45% of the variance in immigrant obesity (p < .01-.001). Similarly, Fitzgerald et al.  discovered that less acculturated Puerto Ricans in the US were 54% less likely to be obese than their more acculturated counterparts. In yet other research on Hmong-American immigrants, higher degree of acculturation also correlated with higher BMI . This relationship was mainly attributed to the changes in diet and physical activity following the adaptation to an environment with higher average income .
Comparable effects have also been found in studies among Korean-Americans  whereby more acculturated men (but not women) had a higher BMI than their enculturated counterparts, with a mean difference in BMI of 1.7kg/m2 (p < .05) . This effect persisted when controlling for age, income, education, working status, and smoking as well as physical activity, fat intake and parents’ body size. In addition, and perhaps paradoxically, acculturated men and women were more likely to engage in light physical activity than enculturated men and women (men OR = 4.34, p < .005; women OR = 7.38, p < .005) .
The final paper included in this review  reported on a longitudinal study which examined the relationship between acculturation and cardiovascular disease risk factors in Soviet Union-born middle-aged women in the US. Similar to some of the other research reviewed, this study established a significant inverse correlation between acculturation score and obesity in women. Specifically, women with higher acculturation scores at baseline predicted lower changes in BMI over the following ten years (r = −.14, p = .05). Similarly, higher enculturation scores predicted higher changes in mean BMI and waist circumference (r = .25, p = .01; r = .34, p = .01, respectively) in the following decade .
Five of the nine studies included measurement of SES [47, 48, 50–52]. Three found no significant correlations between SES and obesity [47, 51, 52], while Fitzgerald et al.  established an inverse correlation between these two variables, and Hazuda et al.  found both positive and negative correlations for men and women, respectively.