Sociodemographic and nutritional determinants of obesity in Belgium.

OBJECTIVE: To examine associations between sociodemographic, dietary factors and physical activity and the prevalence of obesity in the Belgian general population. DESIGN: Base-line data from the Belgian Interuniversity Research on Nutrition and Health (BIRNH) study (1979-1984). SUBJECTS: A total of 5837 men and 5243 women aged 25-74y were included in the analysis. The sample was considered representative of the Belgian population. MEASUREMENTS: Using the body mass index (BMI) as the criterion, obesity was defined as a BMI> or =30 kg/m2. Nutritional data were assessed by a 24 h food record. Physical activity level (PAL) was calculated by dividing total caloric intake by an estimation of basal metabolic rate (BMR, predicted from gender, weight and age). Age-adjusted odds ratios (OR) of the prevalence of obesity were estimated by multilogistic regression analysis. RESULTS: Prevalence of obesity was 12.1% in men and 18.4% in women. In both sexes, prevalence of obesity increased gradually in each 10-year age category (P<0.0001) and steeply decreased with level of education. Comparing lowest (Q1) to highest quartile (Q4), after adjustment for age, prevalence of obesity decreased with total carbohydrate intake, as well as total sugar intake in both sexes, and increased with total fat intake only in men. Obesity increased with a high fat to sugar ratio (men: OR(Q4/Q1) = 1.56; confidence interval (CI): 1.25-1.93; women: OR(Q4/Q1) = 1.45; CI: 1.17-1.80). PAL was inversely and very strongly associated with obesity (men: OR(Q4/Q1) = 0.20; CI: 0.15-0.26; women: OR(Q4/Q1) = 0.18; CI: 0.14-0.23). The same associations were observed with the mean BMI. CONCLUSION: 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.

Trends in the prevalence of obesity among Belgian men at work, 1977-1992.

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 (1992-1993)). DESIGN: Linear regression of the average body mass index (kg/m2) and logistic regression of the prevalence of obesity (BMI > or = 30kg/m2). 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 five-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 > or = 30 kg/m2 doubled over the 15-year period (odds ratio OR (95% confidence 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.