The sweeping environmental change hypothesis: the case of obesity and diabetes among Mediterranean migrants in Belgium

Hadewijch Vandenheede, Vrije Universiteit Brussel
Patrick Deboosere, Vrije Universiteit Brussel

Theoretical background: Large differences in obesity and type 2 diabetes between populations are observed. Particularly high rates of obesity and diabetes are found among migrants in industrialized countries and among urban dwellers in developing countries. To explain this population variability, research often refers to the thrifty genotype and phenotype hypotheses. Both hypotheses consider physiological factors as of uttermost importance, while environmental factors are thought to play second fiddle. In this paper we want to formulate an alternative hypothesis – the sweeping environmental change hypothesis – that supposes social and environmental change to play a key aetiological role in the development of obesity and diabetes. To underpin this hypothesis, we use migration data from Belgium. Method: Obesity and diabetes morbidity were analyzed using the Belgian Health Interview Surveys of 1997, 2001 and 2004. Obesity and diabetes prevalence rates were computed and stepwise logistic regression analyses were conducted. To gain insight in ethnic differences in diabetes mortality, direct standardization and Poisson regression were performed on the basis of the census-linked National Mortality Database 1991-1996 and on the basis of the Brussels Mortality Database 2001-2005. Results: In men no ethnic differences in obesity and diabetes morbidity nor in diabetes mortality were observed. Yet women of Italian, Turkish and Moroccan origin were more likely to be obese and have a higher diabetes prevalence compared to Belgian women. With regard to diabetes mortality, there were indications that mortality was higher among women of Mediterranean origin. Discussion and conclusion: We discuss the results in the light of the thrifty phenotype, the thrifty genotype and the sweeping environmental change hypothesis. We argue that the sweeping environmental change hypothesis fits the data best. We postulate that the (sweeping) change to an ‘obesogenic’ environment is a key fuel of population variability in obesity and diabetes.