A multilevel analysis of variations in body mass index among adults, Brazil, 2006.

OBJECTIVE To analyze the variation in body mass index (BMI) among adults according to individual factors and environmental characteristics of their city of residence. METHODS Data generated in 2006 by the Vigilância de Fatores de Risco e Proteção para Doenças Crônicas por Inquérito Telefônico (VIGITEL--Telephone-based Surveillance of Risk and Protective Factors for Chronic Diseases) system. This survey is based on telephone interviews carried out among probabilistic samples of the population of adults aged > or = 18 years from the 26 Brazilian state capitals and Federal District. Analysis of associated factors included individual socioeconomic and demographic variables and environmental variables pertaining to the city of residence of the 49,395 VIGITEL subjects. Food intake was evaluated based on a 'healthy diet' score and on 'five-a-day' fruit and vegetable intake. Physical activity was evaluated based on frequency and duration of exercise and presence of a place in which to perform physical activity. Associations were tested using multilevel linear models (p<0.05). RESULTS Associations between BMI and individual explanatory variables differed according to sex. Schooling was positively associated with BMI among men, and negatively among women. Five-a-day fruit and vegetable intake was positively associated with BMI among men. In both sexes, presence of a place for physical activity was negatively associated with BMI. CONCLUSIONS Mean BMI differed substantially among Brazilian capitals; however little of this variation could be explained by presence of a place for physical activity or by socioeconomic and diet-related variables.