OBJECTIVE: Research about the prevalence of underweight and overweight/obesity in the Saudi Arabian female population is limited. The aim of the present study was to examine the dietary habits and the prevalence of underweight and overweight/obesity and associated factors among female university students.

DESIGN: A cross-sectional study.

SETTING: A university centre for female students in south-western Saudi Arabia.

SUBJECTS: The study involved 663 randomly selected female university students who self-reported their physical activities, nutritional habits and socio-economic factors. Multiple linear and logistic regression analyses were used to identify factors associated with the students' BMI, dietary variables, underweight and overweight/obesity.

RESULTS: The majority of the university females were normal weight (56·9 %), but a high prevalence of underweight (19·2 %) and overweight/obesity (23·8 %) occurred. Social factors significantly associated with BMI were the presence of obese parents and siblings as well as physical activity levels, marital status, number of sisters, father's level of education and more frequent intake of French fries/potato chips (>3 times/week). Several variables were found to correlate with dietary habits, underweight and overweight/obesity. Of special interest is the association between the number of siblings and the participants' BMI and dietary intake in both negative and positive ways.

CONCLUSIONS: The findings of this research have implications for health promotion and prevention of malnutrition among college-aged females. Health-care providers and policy makers need to involve the whole family when promoting females' physical activity. The study serves as an evidence-based background for planning and implementation of interventions targeting improvement of highly educated populations' nutritional habits.