Purpose: The study aimed to assess the prevalence of underweight and overweight or obesity and their sociodemographic, lifestyle, and health factors in a national adult population in Lao People’s Democratic Republic (PDR) (Laos). Methods: A national cross-sectional study based on a stratified cluster random sampling was conducted in 2013. The total sample included 2531 individuals 18–64 years, (females = 59.3%; mean age 38.7 years, SD = 12.8) from Laos. Questionnaire interview, blood pressure and anthropometric measurements, and biochemistry tests were conducted. Multinomial logistic regression was utilized to determine the association between sociodemographic, lifestyle and health status factors, and underweight and overweight or obesity relative to normal weight. Results: Using Asian criteria for body mass index (BMI) classification, 9.7% of the population was underweight (BMI < 18.5, kg/m2), 47.5% had normal weight (BMI 18.5–22.9 kg/m2), 17.5% overweight (23.0–24.9 kg/m2), 19.6% class I obesity (BMI 25.0–29.9 kg/m2), and 5.6% class II obesity (BMI ≥ 30.0 kg/m2) (or 42.8% overweight, class I or class II obesity). In adjusted multinomial logistic regression, female sex (adjusted relative risk ratio-ARRR 0.67, confidence interval-CI 0.45, 0.99), current tobacco use (ARRR 1.57, CI 1.02, 2.41), and having no hypertension (ARRR 0.50, CI 0.26, 0.97) were associated with underweight, and middle and older age (ARRR 1.79, CI 1.41, 2.25), being Lao-Tai (ARRR 1.37, CI 1.06, 1.76), urban residence (ARRR 1.62, CI 1.20, 2.17), having meals outside home (ARRR 1.36, CI 1.04, 1.77), no current tobacco use (ARRR 0.57, CI 0.34, 0.59), low physical activity (ARRR 1.39, CI 1.01, 1.92), having hypertension (ARRR 2.52, CI 1.94, 3.26), and dyslipidaemia (ARRR 1.56, CI 1.21, 2.00) were associated with overweight or obesity. Conclusion: A dual burden of both adult underweight and overweight or obesity was found in Laos. Sociodemographic, lifestyle, and health status risk factors were identified for underweight and overweight or obesity, which can help in guiding public health programmes to address both these conditions. Level of evidence: Level V, descriptive cross-sectional survey.
