Socioeconomic, psychosocial, behavioural, and psychological determinants of BMI among young women: differing patterns for underweight and overweight/obesity.

OBJECTIVES Underweight, overweight, and obese women aged 18-34 years were compared with normal weight women of the corresponding age according to socioeconomic, psychosocial, health behaviour, self reported global and psychological health, and locus of control characteristics. METHODS The 2000 public health survey in Scania is a cross-sectional study. A total 13,715 persons aged 18-80 years, of which 1967 were females of 18-34 years of age, were included in this study. They answered a postal questionnaire, which represents 59% of the random sample. A logistic regression model adjusted for age was used to investigate the association between socioeconomic, psychosocial, health behaviour, self reported global and psychological health, locus of control, and the BMI categories. RESULTS A 17.5% proportion of the women, aged 18-34 years, were underweight (BMI < 20.0), 18.4% were overweight, and 7.0% obese. The prevalence of underweight according to the BMI < 18.5 definition was 5.8% among women aged 18-34 years. Women who were underweight had significantly higher odds ratios for overtime work, being students, low emotional support, and poor self reported global as well as poor psychological health than normal weight women. Women who were overweight/obese were unemployed, had low education, low social participation, low emotional and instrumental support, were daily smokers, had a sedentary lifestyle, had poor self reported global health, and had lack of internal locus of control compared with normal weight women. CONCLUSIONS Underweight women are more likely to have poorer psychological health than normal weight women. In contrast, overweight and obese women are more likely to have poor health related behaviours and lack of internal locus of control compared with normal weight women. These differing patterns suggest both different etiology and different preventive strategies to deal with the health risks of people who are underweight as opposed to those who are overweight/obese.