Our findings showed an overall decrease in the underweight category (from 8.4% in 2010 to 6.7% in 2016) and in the normal weight category (from 39.9% in 2010 to 36.5% in 2016) and an increase in the overweight category (from 35.1% in 2010 to 38.6% in 2016) and obese category (from 16.7% in 2010 to 18.7% in 2016) in the Singapore adult population, which is consistent with the global trend that has been observed in other studies. In 2008, about 1·5 billion adults globally were overweight, and 502 million adults were obese. While the epidemic started in high income-countries later, a similar increase was seen in middle and low-income countries (mostly in high socioeconomic countries)(10). In 2014, 39% of adults were overweight. 11% of men and 15% of women worldwide were obese. In the South East Asia region, the prevalence of overweight and obese were 22% and 5%, respectively (6).
From a systemic perspective, rising socio-economic status affects the population's lifestyle. People tend to be more sedentary due to longer working hours and are less able to devote time to vigorous physical activities, especially as jobs have become more office-based. (19) Furthermore, the convenience of transportation also plays a part in encouraging sedentary behavior. (10) A study conducted in China found that obesity prevalence is likely to increase among families that own auto-motor vehicles. (20) In Singapore, the car population, has increased from 2010 to 2016 (21) suggests that this could be another contributing factor.
Increased calorie content of food has been used to explain the global rise in body weight and obesity. (22) Overconsumption of food is promoted in the form of increased portion size and more affordable fast food that are high in energy but poor in nutrition. (23) Unhealthy food is more accessible than healthy and nutritious food in the market. (24) Singapore’s active night-life culture, including late-night suppers, might also be associated with the current increasing trend. (25) Emerging literature suggests feeding times may have an effect on metabolism rate and hence influence the development of obesity.(26, 27)
The current study found that age was significantly associated with BMI in both 2010 and 2016. With the economic growth in Singapore in the past couple of decades, people have more access to more nutrition-dense food resulting in changes in their health status.(28) Many studies suggest that the direct reason being human basal metabolism decreases with age due to muscle loss and an increase in body fat. (29, 30)
Gender was also found to be significantly associated with BMI in both 2010 and 2016. This finding is in line with other studies conducted on differences in body mass index and body weight perceptions between the two genders. (31, 32) One explanation could be that females generally have a higher body fat composition than males. (33) A locally based population study found that females, compared to males, are less likely to exercise regularly. (19) Few other studies also found that young females are more sedentary than males because they enjoy socializing more, such as sitting and talking, which could be another possible explanation for current findings on the gender difference. (34, 35)
Compared to degree holders, diploma holders were found less likely to be underweight in 2016 than in 2010, while those with vocational education were more likely to be overweight in 2016 than in 2010. Study findings also suggested that students with pre-university/junior college qualifications are less likely to become obese in 2016 than in 2010. While the findings are consistent with existing literature on the significant association between educational levels and obesity-related behavior, (36) Results did not show a significant inverse relationship between the education levels and BMI categories. Changes between the two time periods for individuals with the same educational level might be explained due to the positive effects of ongoing national programmes in local schools; for example, healthy eating guidelines are provided to help students choose healthy food and beverages. (37) Information regarding healthy ingredients and their suppliers also comply on an official website for school canteen vendors’ reference. (38)
Limitation
Data were collected through self-report from the respondents, so the measurement was subjective, the weight could be under-reported due to embarrassment, and both height and weight could be misreported due to inaccurate recollection. However, the mean differences between self-reported and measured anthropometric values were insignificant in this population (39). Thus, the use of self-reported anthropometric values should not affect the validity of the conclusions drawn in this study. Data did not include those below 18 years of age, which may be an important group to explore.