This study examined the relationship between dietary intake, body weight, and body mass index (BMI) in adult Thais as a function of smoking status. A cross-sectional, nationally representative survey using health and dietary questionnaires and anthropometric measurements were used. Participants were 7858 Thai adults aged 18 years and older recruited from 17 provinces inThailand. Results demonstrated that smoking is associated with lower weights and BMI. However, when smokers were stratified by smoking intensity, there was no dose–response relationship between smoking and body weight. There is no conclusive explanation for weight differences across smoking groups in this sample, and the results of the present study did not clearly support any of the purported mechanisms for the differences in body weight or BMI. In addition, because the substantial negative health consequences of smoking are far stronger than those associated with modest weight differences, smoking cannot be viewed as an appropriate weight management strategy.