Impact of cultural determinants on obesity trajectories

Abstract

Research question: How much do the differences in cultures between countries contribute to their differences in obesity levels and trajectories over time? Aim: The aim of this thesis was to study the effect of national culture and understand its relationship with obesity trajectories between 1975 and 2014. Methods: NCD Risk Factor Collaboration obesity trajectory data was used as the outcome variable measure using national mean body mass index (BMI). The obesity trajectories were adjusted for national income, proportion of population living in urban areas, mean number of years of education and food availability. National culture was measured using the six dimensions of culture in the Geert Hofstede database (power distance, individualism, masculinity, uncertainty avoidance, long-term orientation and indulgence). Multiple linear regressions were conducted for the slope of BMI increase (between 1975 and 2014), intercept (BMI at 1975) and BMI-trend (mean BMI between 1975 and 2014). Where possible, a weighting coefficient was applied to give more weight to better data. Income inequality (the Gini coefficient) was also included as a covariate. Multivariate intercept and BMI-trend analyses for females and males were conducted incorporating all six cultural dimensions in one analysis, and adjusted for a second covariate, region. Findings: 68 countries for the power distance, individualism, masculinity and uncertainty avoidance and 90 cultures for long-term orientation and indulgence were included in the analyses. The cultural dimensions associated with a high BMI at 1975 and a steeper BMI trajectory between 1975 and 2014 was in low power distance societies, high individualistic societies, low masculine societies (for females only), high uncertainty avoidance societies, low long-term orientation (for males only) and highly indulgent societies. The cultural variables collectively explained 40-54% of the differences in BMI in 1975 and 54-65% of the differences in the steepness of trajectories between 1975 and 2014. Conclusion: In this study about half of the differences in obesity between countries can be attributed to differences in culture. Such large effects warrant much more research and cultural dimensions need to be incorporated into current understandings of the obesity epidemic and interventions to reduce obesity.