There is evidence to suggest that immigrant populations from low or medium-income countries to high income countries show a significant change in obesogenic behaviors in the host society, and that these changes are associated with acculturation. However, the results of studies vary depending on how acculturation is measured. The objective of this study is to systematically review the evidence on the relationship between acculturation - as measured with a standardized acculturation scale - and overweight/obesity among adult migrants from low/middle countries to high income countries. A systematic review of relevant studies was undertaken using six EBSCOhost databases and following the Centre for Reviews and Dissemination’s Guidance for Undertaking Reviews in Health Care. The initial search identified 1135 potentially relevant publications, of which only nine studies met the selection criteria. All of the studies were from the US with migrant populations from eight different countries. Six studies employed bi-directional acculturation scales and three used uni-directional scales. Six studies indicated positive general associations between higher acculturation and body mass index (BMI), and three studies reported that higher acculturation was associated with lower BMI, as mainly among women. Despite the small number of studies, a number of potential explanatory hypotheses were developed for these emerging patterns. The ‘Healthy Migrant Effect’ may diminish with greater acculturation as the host culture potentially promotes more unhealthy weight gain than heritage cultures. This appears particularly so for men and a rapid form of nutrition transition represents a likely contributor. The inconsistent results observed for women may be due to the interplay of cultural influences on body image, food choices and physical activity. That is, the Western ideal of a slim female body and higher values placed on physical activity and fitness may counteract the obesogenic food environment for female migrants.

Objectives. There is evidence to suggest that immigrant groups from low- or medium-human development index countries show a significant adoption of obesogenic behaviors and experience weight gain following migration to Australia. The objective of this study is to understand the changes that Iranian immigrants experience in relation to the determinants of obesity after migration to Victoria, Australia. Design. We conducted five focus group discussions with 33 recent Iranian immigrants. This study took an interpretive qualitative approach to data analysis using the constant comparative method. Results. Participants discussed individual level acculturation (e.g., in diet, body size, attitudes), as well as environmental level changes (e.g., physical/structural and sociocultural) that occurred after immigration. Stress during the initial immigration transition, which affected diet and physical activity habits, was a common experience among participants. Gender and the effect of political/religious changes were also important factors. Participants' discourse largely focused on their ability and willingness to adopt positive health behaviors after migration. Conclusion. This study provides insight into the effect of migration on the determinants of obesity among Iranian immigrants in Victoria, Australia, and offers a contrast with the existing evidence by considering the experience of a group that is generally well educated, often emigrates for reasons related to personal freedom as opposed to material deprivation, and has rates of obesity similar to high-income countries.

While migration from low- to high-income countries is typically associated with weight gain, the obesity risks of migration from middle-income countries are less certain. In addition to changes in behaviours and cultural orientation upon migration, analyses of changes in environments are needed to explain post-migration risks for obesity. The present study examines the interaction between obesity-related environmental factors and the pattern of migrant acculturation in a sample of 152 Iranian immigrants in Victoria, Australia. Weight measurements, demographics, physical activity levels and diet habits were also surveyed. The pattern of acculturation (relative integration, assimilation, separation or marginalization) was not related to body mass index, diet, or physical activity behaviours. Three relevant aspects of participants’ perception of the Australian environment (physically active environments, social pressure to be fit, unhealthy food environments) varied considerably by demographic characteristics, but only one (physically active environments) was related to a pattern of acculturation (assimilation). Overall, this research highlighted a number of key relationships between acculturation and obesity-related environments and behaviours for our study sample. Theoretical models on migration, culture and obesity need to include environmental factors.

Although there are a number of studies examining the effect of migration on obesity, these studies tend to focus on the role of acculturation in this relationship. However, there are indications that the change in environment may also be an important factor. Indeed, there is a considerable lack of psychometric tools designed to assess the association between environment and migrant health behaviour. The current study aimed to assess the literature on the link between environment and health for migrants, and on the basis of this information, design and develop the Migrant Obesogenic Perception of the Environment questionnaire (MOPE-Q). The MOPE-Q is the first comprehensive measure of the impact of environmental factors on migrant health behaviour related to physical activity, food habits and body image concern, as well as weight change. Using a systematic approach, an initial pool of items for the questionnaire was developed and refined on the basis of rigorous content and face validity assessments and factor analysis. Further, reliability tests and test re-test studies were undertaken. Differences between Iranian and Australian environmental factors as they relate to obesogenic behaviour were explored using the developed measure. A total of 36 items were developed for the MOPE-Q. Principal factor analysis identified three similar factor structures of environmental factors related to obesity (categorized in terms of facilitators, barriers and pressures) for each country. The final questionnaire consisted of four distinct subscales pertaining specifically to the Australian environment and five subscales pertaining to the Iranian environment, accounting for 59% and 63%, respectively, of the total variance in obesity rates. Data suggests that the MOPE-Q is a reliable and valid self-report measure for assessing the relationship between environmental factors linked to obesity and obesogenic behaviour for this particular migrant group. The variations in environmental factors linked to obesity behaviour between home (Iran) and host (Australia) countries have been incorporated into the MOPE-Q instrument which has shown good psychometric properties. The MOPE-Q can be adapted and applied to other environments and populations to help explain changes in diet, physical activity patterns and body weight in migrant groups as they acculturate.