Determinants of body mass index : a study from Northern Italy

Overweight and obesity are associated with increased mortality and morbidity, and human weight is influenced by multiple factors, both genetically and environmentally determined. We investigated the influence of some socioeconomic, behavioral, dietary and reproductive factors on body mass index (BMI). Data were obtained from a comparison group of a case-control study of gastrointestinal cancers from the four largest teaching and general hospitals in Milan, northern Italy. The subjects were 1,188 men and 832 women admitted between January 1985 and June 1992 to the hospitals under study for diseases other than malignant or digestive and not known or suspected to be related to alcohol or tobacco. The following were measured: BMI (Quetelet's index, weight, kg/height, m2) and the corresponding standard errors (s.e.) in strata of selected variables, linear regression coefficients (β) and correlation coefficients between BMI and each variable. Mean BMI increased with age until 35-44 years in men and 45-54 years in women. In both sexes BMI was inversely associated with education and social class. Smokers tended to be leaner than non-smokers, but no consistent trend was observed with increasing numbers of cigarettes. Alcohol drinkers had mean BMI similar to non-drinkers, except heavy drinking women who were lighter. BMI was not significantly associated with coffee, decaffeinated coffee, tea, bread, vegetable and fruit consumption. No relation was observed between total estimated caloric intake and BMI. In women BMI was directly associated with marriage and number of children, and inversely with oral contraceptive use. It was concluded that socioeconomic, behavioral and reproductive factors influence BMI in this Italian population, particularly in women. Reported diet appeared to have little influence.