This study indicates that prevalence of obesity is particularly high in Belgium. Low level of education and reduced physical activity, increased fat intake and especially elevated fat to sugar ratio appear to be powerful determinants of obesity in this Belgian population.

OBJECTIVE: To assess trends in average body mass index (BMI) and the prevalence of obesity between 1977 and 1992, in middle-aged Belgian men at work. SUBJECTS: A subsample of men at work, aged 40 ± 54 y extracted from the base-line data from four independent prospective studies, each representing a period (Physical Fitness Study (1977 ± 1978, Belgian Interuniversity Research on Nutrition and Health (BIRNH) (1979 ± 1984), Multinational Monitoring of Trends and Determinants in Cardiovascular Diseases (MONICA) (1986 ± 1991) and ORCA (1992ORCA ( ± 1993). DESIGN: Linear regression of the average body mass index (kg/m 2 ) and logistic regression of the prevalence of obesity (BMI ! 30 kg/m 2 ). Independent variables taken into account in multivariate analysis were: age, educational level, marital status and region. RESULTS: In this subsample of Belgian men at work, aged 40 ± 54 y, prevalence of obesity increased from 9.2% in 1977 ± 1978 to 14.5% in 1992 ± 1993. This rise was present in each ®ve-year age group, in both regions and in all educational groups, but strongest in the lowest educated. After adjustment for sociodemographic covariables, it was estimated that with regard to 1977 ± 1978, the proportion of men with a BMI ! 30 kg/m 2 doubled over the 15-year period (odds ratio OR (95% con®dence intervals, 95% CI)): 1.98 (1.40; 2.80). CONCLUSION: Keeping in mind that the trends have been calculated from data from four different studies, presenting some shortcomings, prevalence of obesity has increased between 1977 ± 1992 in men aged 40 ± 54 y at work. This rise is particularly pronounced in the lower educated groups.