BackgroundExtended life spans have led to an increase in the number of older people and an increase in the prevalence of disability among people older than 60 years of age.ObjectiveThis study aims to investigate the association of sociodemographic variables and unhealthy behaviors with limitations in activities of daily living (ADL) among Thai older adults. The study also projects the number of older individuals likely to experience ADL limitations in the next 20 years.MethodsWe performed sex-specific multinomial logistic regression analysis based on the 5th Thai National Health Examination Survey in 2014 to investigate the association between sociodemographic variables and health behaviors with ADL limitations among Thai older adults. Age- and sex-specific prevalence estimates of ADL limitations were obtained by applying the same models. These estimates were combined with population projections up to 2040 from the Office of the National Economic and Social Development Board, Thailand, to generate projections of older individuals with ADL limitations.ResultsAge and physical activity were significant factors for both sexes, with age positively associated with the level of ADL limitations and low physical activity associated with an increased relative probability of mild or moderate to severe ADL limitations compared to individuals with no ADL limitation (1.2-2.2 times). Other variables such as education, marital status, diabetes, hypertension, smoking, alcohol consumption, and having a fruit- and vegetable-based diet showed significant associations, but the results varied regarding sex and levels of ADL limitations. This study also projected the number of older adults with mild and moderate to severe ADL limitations over the next 20 years from 2020 to 2040, revealing an increase of 3.2 and 3.1 times, respectively, along with a significant increase in men compared to that in women.ConclusionsThis study identified age and physical activity as significant factors associated with ADL limitations in older adults, while other factors showed varying associations. Over the next 2 decades, projections suggest a significant increase in the number of older adults with ADL limitations, particularly men. Our findings emphasize the importance of interventions to reduce ADL limitations, and health care providers should consider various factors impacting them.