Educational level, relative body weight, and changes in their association over 10 years: an international perspective from the WHO MONICA Project

OBJECTIVES: This study assessed the consistency and magnitude of the association between educational level and relative body weight in populations with widely different prevalences of over-weight and investigated possible changes in the association over 10 years. METHODS: Differences in age-adjusted mean body mass index (BMI) between the highest and the lowest tertiles of years of schooling were calculated for 26 populations in the initial and final surveys of the World Health Organization (WHO) MONICA (Monitoring Trends and Determinants in Cardiovascular Disease) Project. The data are derived from random population samples, including more than 42,000 men and women aged 35 to 64 years in the initial survey (1979-1989) and almost 35,000 in the final survey (1989-1996). RESULTS: For women, almost all populations showed a statistically significant inverse association between educational level and BMI; the difference between the highest and the lowest educational tertiles ranged from -3.3 to 0.4 kg/m2. For men, the difference ranged from -1.5 to 2.2 kg/m2. In about two thirds of the populations, the differences in BMI between the educational levels increased over the 10-year period. CONCLUSION: Lower education was associated with higher BMI in about half of the male and in almost all of the female populations, and the differences in relative body weight between educational levels increased over the study period. Thus, socioeconomic inequality in health consequences of obesity may increase in many countries.