Lifestyle, social class, and obesity-the Copenhagen Male Study

With the implicit purpose of identifying relevant intervention targets, the aim of the study was to test if lifestyle factors associated with obesity are unevenly distributed across social groups, and whether an uneven distribution of such factors may contribute to the explanation of social differences in obesity.

Cross-sectional study of 3290 men aged 53-75 years (mean=63) carried out in 1985-1986 using in addition, data from a previous baseline established in 1970-1971. Information about lifestyle factors was obtained from a questionnaire validated during an interview. Potential risk factors were smoking history, alcohol consumption, leisure time physical activity (LTPA), and from the 1985-1986 study only: consumption of tea and coffee, use of sugar in tea or coffee, and avoidance of fat in foods. The clinical examination included measurements of height and weight. Obesity was defined as a body mass index > or =30 (BMI=kg/m2). Based on information about education and job profile the men were subdivided into five social classes.

Overall, 291 men (8.8%) were obese. The lower the social class the higher the proportion of obese men: in social classes I and II, 4.5% (of 953), social class III, 9.1% (of 636), social class IV, 11.1% (of 1353), and social class V, 11.6% (of 346), P<0.001 (trend test). Leisure time physical activity, alcohol consumption, smoking habits, use of sugar in hot beverages, and consumption of coffee and tea, were all significantly associated with obesity, either positively or negatively, and even significantly associated with social class. Based on these lifestyle factors it was possible to discriminate subgroups with highly different prevalences of obesity. Despite this, adjustment for identified obesity covariates in a multiple logistic regression analysis did in no way explain the association of social class with obesity.

Lifestyle factors in concert strongly associated with obesity are unevenly distributed across social classes, yet incapable of explaining the higher prevalence of obesity in lower social classes.