Cigarette smoking is considered as a major risk factor for leading causes of death worldwide including cancers and cardiovascular disease. Compared to developed countries, the smoking rate in developing countries has been alarmingly increasing. Thailand, in particular, is also facing the same challenge. It has been established that smokers tended to have unhealthy dietary intake, and have lower body weight and body mass index compared to non-smokers. Not many studies have observed the prevalence of smoking and its association with body mass index and body weight in Asia and in Thailand. The aims of this study were to determine smoking prevalence and to examine the relationship between smoking, dietary intake pattern and body mass index of Thai adults. Participants aged 18 and over were randomly selected across Thailand using a multistage, random sampling strategy. A structured interview incorporating health questionnaire, 24-hour dietary recall and anthropometric measurements were applied.

In this study population, 22.2% were smokers (41.3% of men and 3.8% of women). Smoking prevalence was much higher in men than women across age groups and across regions. In both genders, current smokers were less educated, had lower level job and lower household annual income. Regarding to dietary intake, there were not substantial significantly differences among smoking group. However, current smokers have lower body mass index and body weight than their non-smoking counterparts, regardless of gender. In addition, a U-shaped relationship between number of cigarettes smoked per day and body mass index was found in this population, with the lowest body mass index in those smoking 1-9 cigarettes per day. Heavy smokers and never-smokers had similar body mass index.

Results from this study are consistent with other reports showing that smoking is associated with lower body weight and body mass index when compared to non-smokers. The mechanism for this association may be partially related to the potential for nicotine to increase metabolic rate rather than appetite suppression in smokers. In conclusion, 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.