Longitudinal study of the socio-demographic determinants of changes in body weight and waist circumference in a multi-ethnic Asian population

Objective: To examine the changes in weight and waist circumference of adult Singaporeans between 1998 and 2005-2007, and the associations of these changes with demographic and socio-economic factors. Methodology: A prospective study, which followed up participants aged 18-69 years from the 1998 National Health Survey. Analysis was performed on data from 2483 individuals (53% of original sample) who returned for follow-up in 2005-2007. Body weight and waist circumference were measured both at baseline and follow-up. Logistic regression was used to examine factors associated with being overweight and obese at baseline. Linear regression was used to examine changes in weight and waist circumference over time. The variables examined were age, gender, ethnicity, marital status, educational level, housing and employment status, smoking, alcohol consumption and sports activities. Results: Mean weight for the population increased over the follow-up period by 1.48 kg (s.d. = 4.95) and mean waist circumference increased by 3.32cm (s.d. = 7.92). Cross-sectionally, those who were overweight or obese were more likely to be Malays or Indians, married, homemakers and have lower educational level. Prospectively, individuals who gained the most weight were younger, more likely to be ethnic minority groups and have the lowest body mass index (BMI) at baseline. They also appeared to be of higher socio-economic status (SES) based on housing type. These associations were statistically significant even after adjusting for other variables. Conclusion: Obesity prevention should start early in the younger age. Preventive programs need to reach out to Malay and Indian ethnic groups and those with higher SES. These findings should be used in designing messaging of preventive strategies. International Journal of Obesity (2009) 33, 1299-1308; doi:10.1038/ijo.2009.173; published online 8 September 2009