This paper focuses on prevalence of nutritional status (Body Mass Index, BMI) in social groups in Greater Metropolitan São Paulo, in Southeastern Brazil. The population was stratified in four socioeconomic groups. Prevalence of malnutrition (BMI < 18.5kg/m2), low body mass (BMI < 20.0kg/m2), and overweight (BMI > 25.0 kg/m2) and obesity (BMI > or = 30.0kg/m2) were calculated. Prevalence of malnutrition was 3.9% in men and 6.2% in women. Prevalence of overweight ranged from 27.5% to 34.1% in men and from 25.8% to 43.6% in women. Obesity ranged from 2.5% to 11.1% in men and from 7.1% to 20.5 in women. Prevalence of overweight and obesity was greater among women than men (p<0.01). In relation to excess weight (BMI > 25.0 kgm/2), the study showed that prevalence in men was 43, 51, 35, and 30% for strata I, II, III, and IV, respectively. Among women, prevalence was 12, 61, 55 and 46% for strata I, II, III, and IV, respectively. In women there were an abrupt increase in excess weight just before 40 years of age. A high percentage of overweight and obesity was observed in all population groups.