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Keywords:

  • prevalence;
  • trends;
  • epidemiology;
  • education;
  • socioeconomics

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Objective: To measure trends in the prevalence of overweight and obesity and the relationship with urban or rural residence and education in Thailand.

Research Methods and Procedures: Data were from two nationally representative surveys of 38,323 individuals ≥18 years old (19,156 were 18 to 59 years old) in 2004 and 3375 individuals 18 to 59 years old in 1997. Overweight and obesity were defined using the World Health Organization's Asian criteria.

Results: Among those ≥18 years old in 2004, 17.8% of men (95% confidence interval, 16.6% to 19.0%) were overweight, 18.4% (17.3% to 19.5%) had Class I obesity, 4.8% (4.1% to 5.5%) had Class II obesity, and 15.9% (14.6% to 17.1%) had abdominal obesity. In women, 18.2% (17.1% to 19.2%) were overweight, 26.1% (24.9% to 27.3%) had Class I obesity, 9.3% (8.6% to 10.0%) had Class II obesity, and 37.3% (35.3% to 39.2%) had abdominal obesity. In those 18 to 59 years old, the prevalence of Class I obesity in men and all four categories in women significantly increased between 1997 and 2004. There was an inverse relationship in women but a positive relationship in men between education and the odds of being overweight or obese. In 2004, there were significantly lower odds of being overweight or obese in rural compared with urban men but similar odds between urban and rural women.

Discussion: The prevalence of overweight and obesity in Thailand is high and increasing. Although the transition of overweight and obesity to those of lower socioeconomic status is not complete, it is well on the way.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Over the last decade, excess body weight has become a global public health epidemic. One billion seven-hundred million individuals were estimated to be overweight in 2005 (BMI ≥ 25 kg/m2, BMI ≥23 kg/m2 in Asian populations) (1), and being overweight was the eighth most important risk factor contributing to the total global burden of disease in 2001 (2). The epidemic is occurring across the globe with growing prevalence in the developing world, due largely to the rapid changes in behavior and lifestyle, such as diet and physical activity, which have accompanied economic development (3). At the early stages of economic development, overweight and obesity tend to be associated with high socioeconomic status (SES)1 and urban populations (4), but as economic output increases, this association shifts toward those with lower SES (5), with this shift occurring earlier in women than it does in men (6)(7).

In Thailand, overweight and obesity have become increasingly prominent public health priorities (8), with non-communicable disease and risk factors playing a growing role as the country moves through the epidemiological transition from infectious to predominantly chronic diseases (9). In 1999, obesity was the seventh ranked risk factor in men (2.4% of all disability-adjusted life years in men) and the second ranked risk factor in women (6.1% of all disability-adjusted life years in women) (8). Increasing urbanization and ongoing economic growth mean that health risks attributable to overweight and obesity are likely to rise further (10). Recent evidence on the size of the problem, trends over time, and the association with socioeconomic factors in Thailand, however, is scarce. Such evidence is crucial for health systems if they are to adequately plan for, and respond to, the growing problem of overweight and obesity. In this paper, we present results from the Third National Health Examination Survey (NHES III) conducted in 2004 on the prevalence of overweight and obesity in Thailand, examine trends over time by reanalyzing the Second National Health Examination Survey (NHES II) conducted in 1997, and quantify the association of overweight and obesity with urban or rural residence and education for both time-points.

Research Methods and Procedures

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

NHES III was conducted by the Health Systems Research Institute (see “Acknowledgments”), with data collection conducted between January and May, 2004. NHES II was conducted in 1997. Both studies were approved by the relevant ethics committee at the time, and participants provided written informed consent.

Sample Design

NHES III was a nationally representative cross-sectional survey, using multistage, stratified, cluster sampling. The total target sample size was 42,120 participants over 15 years of age. For all areas except Bangkok, three provinces in each of the 12 public health areas were selected based on probability proportional to size (PPS). At the second stage, nine electoral units (EUs) or villages were selected by PPS from both urban and rural areas. At the final stage and for each EU/village, 15 individuals were selected by simple random sampling, with replacement from government registers of households and individuals, from each of four broad age and sex groups (men/women, 15 to 59/60+ years). Replacements were within a 5-year age range and of the same sex and EU/village. In Bangkok, nine EUs were selected by PPS and EU/village. The final sampling stage was identical to that used in the other 12 public health areas. The final collected sample for NHES III was 39,290 individuals (18,934 men and 20,356 women) of the target sample size of 42,120 (93.3%).

NHES II has been described in detail elsewhere (11). Briefly, a multistage, stratified, cluster sampling frame was used. At the first stage, eight provinces from regional strata (central, northeast, north, south) and eight districts from Bangkok were selected. In each selected province/district, up to eight EUs and up to nine villages were randomly selected from urban and rural strata. The number of EUs/villages was proportional to the size of the population in the corresponding strata. Fifteen individuals from four age groups (0 to 5, 6 to 12, 13 to 59, and 60+ years) were then systematically sampled. The total target sample size was 20,040 individuals, with a final collected sample of 15,822 (7279 men and 8543 women; 79.0% of target sample).

Data Collection and Measurement

In both surveys, data were collected by interview and physical examination. The questionnaire was administered by a trained interviewer according to standard protocol (12) and collected information on demographic characteristics, including total years of education. The physical examination was conducted at a field survey site, with anthropometric measurements, including weight, height, and waist circumference (WC), measured by a trained technician using standardized procedures and equipment. WC was measured from the horizontal plane at a level midway between the lower rib margin and iliac crest with the measuring tape all around the body, while the participant stood erect, abdomen relaxed, arms at the side, and feet together with weight equally distributed over both legs. Participants were told to breathe normally and gently and not to hold in their abdomen or their breath. The measurement was read at the end of a gentle exhale.

Definitions

The Asian criteria for BMI were used, with overweight defined as 23 ≤ BMI < 25 kg/m2, Class I obesity defined as 25 ≤ BMI < 30 kg/m2, and Class II obesity defined as BMI ≥ 30 kg/m2 (13)(14). Abdominal obesity was defined as WC ≥ 90 cm for men and ≥80 cm for women (13). Education was categorized into four levels: less than primary education, primary education, secondary or vocational education, and tertiary education. Smoking status was categorized from self-reported data as current smoker or non-smoker. Marital status was also self-reported and categorized as single, married, or divorced/widowed/separated.

Statistical Analysis

Both surveys were sample weighted against the relevant national population of the time; the NHES III was weighted against the total national registered population for 2004, and the NHES II was weighted against the 2000 population census, the closest year for which national population data were available. In this analysis, we restricted observations to those at least 18 years of age (N = 38,323) to account for different overweight and obesity criteria for adolescents. Using Stata 9.2 (StataCorp LP., College Station, TX), robust methods of variance estimation were used to take into account the complex survey design. Statistical significance between men and women in 2004 was determined using the adjusted Wald test, with a p value < 0.05 considered statistically significant. Because measurements of height, weight, and WC were conducted only for those 18 to 59 years of age in NHES II, comparisons over time are limited to this age group (N = 19,156 for NHES III, N = 3375 for NHES II) and were age- and sex-standardized to the 2004 national population. Statistical significance between the 1997 and 2004 prevalence estimates was determined with a standard z test (15) using SE estimates for each of the time-points derived from the robust variance estimation described above. Logistic regression was used to examine the relationship of education and urban/rural residence with abdominal obesity, controlled for age (in 10-year age groups), geographic region, smoking status, and marital status. For overweight and obesity measured by BMI, continuation ratio ordinal logistic regression (16), controlled for the same factors, was used to determine odds ratios (ORs) for levels of education and urban or rural residence for the following comparisons: Class II obesity vs. Class I obesity, overweight or normal weight; Class I obesity vs. overweight or normal weight; and overweight vs. normal weight. Regression models were run separately for men and women.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Prevalence of Overweight, Obesity, and Central Obesity, Thailand 2004

Among Thai men at least 18 years old in 2004, mean BMI was 22.7 kg/m2 (SE 0.1), and mean WC was 79.0 cm (SE 0.3). In women of the same age, mean BMI was 23.9 kg/m2 (SE 0.1), and mean WC was 77.0 cm (SE 0.3). BMI was significantly higher in women than in men (p < 0.001), but WC was lower (p < 0.001). Among the Thai population ≥18 years old in 2004, 18.0% [95% confidence interval (CI), 17.2% to 18.7%] were overweight (23 kg/m2 ≤ BMI < 25 kg/m2), 22.4% (95% CI, 21.5% to 23.3%) had Class I obesity (25 kg/m2 ≤ BMI < 30 kg/m2), and 7.1% (95% CI, 6.6% to 7.7%) had Class II obesity (BMI ≥ 30 kg/m2). In the same population, 26.8% (95% CI, 25.5% to 28.3%) had abdominal obesity (WC ≥ 90 cm in men, ≥80 cm in women) and 21.3% (95% CI, 20.2% to 22.4%) were obese (BMI ≥25 kg/m2) with abdominal obesity.

In both sexes, the prevalence of overweight and obesity increased with age, peaking at 45 to 54 years of age and declining thereafter (Figure 1). Women were no more likely than men to be overweight (18.2% vs. 17.8%; p = 0.668 for the age-standardized comparison) but were more likely to have Class I obesity (26.1% vs. 18.4%; p < 0.001), Class II obesity (9.3% vs. 4.8%; p < 0.001), or abdominal obesity (37.3% vs. 15.9%; p < 0.001), or to be both obese and have abdominal obesity (28.3% vs. 13.9%; p < 0.001).

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Figure 1. : Prevalence of overweight (23 ≤ BMI < 25), Class I obesity (25 ≤ BMI < 30), Class II obesity (BMI ≥ 30), and abdominal obesity (WC ≥90 cm in men, ≥80 cm in women) by age and sex, Thailand 2004. (A) Men, overweight, Class I and Class II obesity. (B) Women, overweight, Class I and Class II obesity. (C) Men, abdominal obesity. (D) Women, abdominal obesity.

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Trends in the Prevalence of Overweight, Obesity, and Abdominal Obesity, Thailand, 1997 and 2004

Between 1997 and 2004, among Thai adults 18 to 59 years of age, the age-standardized prevalence of overweight increased from 16.2% to 18.2% (Figure 2; 12.8% relative increase from 1997 to 2004, p < 0.01), Class I obesity increased from 19.3% to 22.8% (18.2%, p < 0.001), Class II obesity increased from 6.3% to 7.5% (20.1%, p < 0.05), and abdominal obesity increased from 22.5% to 26.3% (16.5%, p < 0.01). Age-standardized prevalence increased significantly across all measures in women 18 to 59 years of age between 1997 and 2004 (Figure 2A). Although the age-standardized prevalence of overweight or obesity among men was higher in 2004 compared with 1997, only the prevalence of Class I obesity increased significantly (Figure 2B).

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Figure 2. : Age-standardized prevalence of overweight (23 ≤ BMI < 25), Class I obesity (25 ≤ BMI < 30), Class II obesity (BMI ≥ 30), and abdominal obesity (WC ≥90 cm in men, ≥80 cm in women) in adults 18 to 59 years of age by sex, Thailand 1997 and 2004. (A) Men. (B) Women. * p < 0.05. ** p < 0.01. Error bars are 95% CIs.

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Relationship of Urban or Rural Residence and Education with Overweight, Obesity, and Abdominal Obesity, Thailand, 1997 and 2004

Table 1 shows the age-standardized prevalence of overweight, Class I obesity, Class II obesity, and abdominal obesity by urban or rural residence and by education levels for adults 18 to 59 years of age in 1997 and 2004. Table 2 shows the result from a continuation ratio ordinal logistic regression of overweight, Class I obesity, and Class II obesity and a logistic regression of abdominal obesity against urban/rural residence and education for adults 18 to 59 years of age by sex in 1997 and 2004. In 2004, rural men were less likely than urban men to be overweight or obese across all measures (Table 2). Among women in 2004, rural women were less likely to have Class II obesity than their urban counterparts but had similar odds for other measures of overweight or obesity. Having higher education was usually associated with a higher probability of being overweight or obese in men, whereas an inverse relationship was generally observed for education in women for all measures of overweight and obesity (Table 2). Overall, ORs in 1997 were similar to those in 2004, but the smaller sample size meant that estimates were less precise with larger CIs.

Table 1. . Age-standardized* prevalence (95% CIs) of overweight (23 ≤ BMI < 25), Class I obesity (25 ≤ BMI < 30), Class II obesity (BMI ≥ 30), and abdominal obesity (WC ≥90 cm in men, ≥80 cm in women) by sex, urban/rural residence, and level of education for adults 18 to 59 years of age, Thailand 1997 and 2004 (N = number of respondents in particular strata)
 Sample size (N)OverweightObesity Class IObesity Class IIAbdominal obesity
 MenWomenMen (95% CI)Women (95% CI)Men (95% CI)Women (95% CI)Men (95% CI)Women (95% CI)Men (95% CI)Women (95% CI)
  • CI, confidence interval; WC, waist circumference; NHES II, Second National Health Examination Survey; NHES III, Third National Health Examination Survey.

  • *

    Age-standardized to the 2004 national population.

NHES II (1997):          
 Area of residence          
  Urban46692419.9% (17.3, 22.8)12.9% (11.1, 14.9)20.4% (17.2, 24.1)23.9% (22.0, 26.0)7.1% (5.4, 9.3)9.9% (8.7, 11.1)23.4% (18.2, 29.5)32.0% (29.5, 34.6)
  Rural705107814.9% (13.2, 16.7)17.3% (15.8, 19.0)13.3% (11.4, 15.5)22.1% (19.5, 25.0)2.8% (1.7, 4.7)7.7% (6.5, 9.2)10.1% (7.7, 13.1)29.6% (27.2, 32.2)
 Education          
  Less than primary5913318.3% (10.5, 29.9)20.3% (13.6, 29.2)28.3% (18.3, 41.0)17.1% (13.2, 21.9)0.3% (0.1, 1.6)9.3% (5.5, 15.3)11.2% (6.0, 20.1)25.8% (20.4, 32.2)
  Primary642113116.1% (13.8, 18.8)16.7% (14.9, 18.7)11.7% (9.9, 13.9)24.5% (22.5, 26.6)2.8% (1.8, 4.4)8.8% (7.5, 10.3)9.5% (6.9, 12.8)32.5% (30.2, 34.9)
  Secondary or vocational35349320.3% (17.2, 23.7)13.2% (10.8, 15.9)20.8% (17.8, 24.1)22.7% (20.0, 25.7)6.5% (4.1, 10.1)8.0% (5.8, 10.9)23.2% (19.5, 27.3)27.1% (23.8, 30.7)
  University or higher9617915.3% (7.7, 28.1)12.3% (9.9, 15.2)28.3% (23.7, 33.3)15.3% (11.6, 20.0)5.6% (2.1, 13.7)5.4% (3.0, 9.7)25.3% (20.0, 31.5)24.3% (20.0, 29.1)
 Total  16.5% (14.6, 18.7)15.8% (14.2, 17.6)15.7% (13.5, 18.1)22.7% (21.1, 24.4)4.1% (2.9, 6.0)8.3% (7.3, 9.4)14.3% (10.7, 18.7)30.3% (28.5, 32.2)
NHES III (2004):          
 Area of residence          
  Urban4654547419.1% (17.6, 20.6)17.5% (16.2, 18.8)25.1% (23.6, 26.6)25.4% (24.1, 26.7)7.1% (6.1, 8.3)12.3% (11.1, 13.7)22.7% (21.1, 24.3)37.2% (34.8, 39.7)
  Rural4425458017.8% (16.1, 19.6)18.6% (17.1, 20.3)16.8% (15.4, 18.2)26.9% (25.2, 28.6)4.5% (3.7, 5.6)8.8% (8.0, 9.8)13.4% (12.0, 14.9)36.0% (33.7, 38.3)
 Education          
  Less than primary16846413.4% (7.4, 23.0)19.7% (15.3, 25.0)17.5% (10.6, 27.4)32.7% (25.2, 41.3)5.6% (2.8, 10.8)7.0% (4.4, 10.8)13.8% (9.4, 19.8)34.3% (27.6, 41.7)
  Primary5221569817.4% (15.5, 19.6)20.0% (18.3, 21.7)17.0% (15.6, 18.5)28.3% (26.4, 30.4)4.3% (3.3, 5.5)10.4% (9.2, 11.6)13.6% (12.0, 15.4)39.5% (36.7, 42.4)
  Secondary or vocational2865245419.2% (17.2, 21.4)18.1% (15.9, 20.4)22.2% (20.3, 24.3)25.0% (22.7, 27.4)5.9% (4.8, 7.2)9.4% (8.0, 10.9)19.0% (17.1, 21.0)33.8% (31.2, 36.5)
  University or higher82083122.7% (19.4, 26.3)14.5% (11.6, 18.0)24.8% (21.4, 28.5)20.7% (17.1, 24.8)7.3% (5.3, 9.9)7.8% (5.8, 10.6)22.5% (19.3, 26.2)23.0% (19.5, 27.0)
 Total  18.1% (16.8, 19.5)18.4% (17.2, 19.6)18.8% (17.7, 20.0)26.5% (25.2, 27.9)5.2% (4.5, 6.0)9.8% (9.0, 10.5)15.7% (14.4, 17.0)36.3% (34.4, 38.3)
Table 2. . Adjusted* ORs (95% CIs) for overweight (23 ≤ BMI < 25), Class I obesity (25 < BMI < 30), Class II obesity (BMI ≥ 30), and abdominal obesity (WC ≥ 90 cm in men, ≥ 80 cm in women) as determined by logistic regression, by sex, adults 18 to 59 years of age, Thailand 1997 and 2004 (N = number of observations in logistic regression)
FactorsOverweightObesity Class IObesity Class IIAbdominal obesity
 Men (95% CI)Women (95% CI)Men (95% CI)Women (95% CI)Men (95% CI)Women (95% CI)Men (95% CI)Women (95% CI)
  • OR, odds ratio; CI, confidence interval; WC, waist circumference; NHES II, Second National Health Examination Survey; NHES III, Third National Health Examination Survey.

  • *

    Adjusted for age (18 to 24 years, 10-year age groups up to age 59), geographic region (central, north, northeast, south, Bangkok), smoking status (current smoker, non-smoker), and marital status (single, married, divorced/separated/widowed).

NHES II (1997)N = 902N = 1310N = 1103N = 1782N = 1158N = 1957N = 1195N = 2003
 Area of residence        
  Urban1.001.001.001.001.001.001.001.00
  Rural0.76 (0.52, 1.13)1.13 (0.88, 1.47)0.86 (0.63, 1.19)0.73 (0.56, 0.96)0.77 (0.37, 1.63)0.76 (0.56, 1.05)0.74 (0.45, 1.21)0.74 (0.61, 0.88)
 Education        
  Less than primary1.001.001.001.001.001.001.001.00
  Primary0.71 (0.31, 1.63)1.17 (0.82, 1.67)0.50 (0.28, 0.87)1.42 (0.99, 2.06)2.64 (0.49, 14.34)0.85 (0.54, 1.35)0.88 (0.44, 1.75)1.42 (0.99, 2.05)
  Secondary or vocational0.93 (0.39, 2.23)0.82 (0.52, 1.29)0.88 (0.47, 1.63)1.18 (0.83, 1.68)4.63 (0.78, 27.38)0.68 (0.33, 1.4)2.02 (0.94, 4.34)1.02 (0.67, 1.55)
  University or higher0.46 (0.16, 1.32)0.71 (0.46, 1.11)1.07 (0.46, 2.46)0.64 (0.34, 1.21)2.72 (0.1, 71.01)0.36 (0.14, 0.9)1.53 (0.73, 3.21)0.88 (0.51, 1.51)
NHES III (2004)N = 6384N = 5748N = 8544N = 8855N = 9079N = 10,060N = 9085N = 10,052
 Area of residence        
  Urban1.001.001.001.001.001.001.001.00
  Rural0.76 (0.65, 0.9)0.89 (0.75, 1.06)0.64 (0.56, 0.72)0.89 (0.79, 1.01)0.68 (0.54, 0.85)0.74 (0.62, 0.89)0.63 (0.55, 0.73)0.91 (0.8, 1.02)
 Education        
  Less than primary1.001.001.001.001.001.001.001.00
  Primary1.40 (0.78, 2.51)1.21 (0.84, 1.73)1.07 (0.55, 2.11)1.09 (0.82, 1.46)0.65 (0.29, 1.44)1.17 (0.82, 1.66)0.92 (0.56, 1.53)1.25 (0.94, 1.67)
  Secondary or vocational1.65 (0.89, 3.06)0.88 (0.59, 1.3)1.29 (0.64, 2.58)0.83 (0.6, 1.17)0.86 (0.37, 1.95)0.85 (0.56, 1.29)1.12 (0.66, 1.9)0.89 (0.62, 1.29)
  University or higher1.97 (1.08, 3.57)0.60 (0.35, 1.03)1.42 (0.67, 3.01)0.70 (0.47, 1.02)1.01 (0.44, 2.32)0.62 (0.36, 1.07)1.35 (0.81, 2.26)0.62 (0.41, 0.92)

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

This study demonstrates that the prevalence of overweight and obesity in Thailand has risen dramatically, such that in 2004, almost 3 of 10 Thai adults were obese (BMI ≥ 25 kg/m2), and almost one-fifth were overweight (23 kg/m2 ≤ BMI < 25 kg/m2), with women at markedly higher risk than men of being overweight or obese. This translates into 12.8 million obese and nearly 8 million overweight Thai adults. Although these levels are lower than those of countries such as the United States (17), they are comparable with other rapidly developing Asian populations such as China (18).

Perhaps most importantly, overweight and obesity are no longer restricted to urban or higher socioeconomic portions of the Thai population, as is typically found in countries at earlier stages of development (19). Although differentials exist between urban and rural men, the odds of being overweight or obese were similar in urban and rural women, except for Class II obesity, for which rural women had lower odds. A greater likelihood of being overweight or obese with decreasing levels of education was seen in women, whereas a positive relationship with education was seen in men. The earlier shift of the burden toward the portion of the population with lower education seen in women is consistent with studies from other developing countries (20).

What determinants underlie these findings? Rising prevalence is likely linked to changing food consumption patterns from a predominantly high-vegetable, carbohydrate-based diet to one consisting of a larger proportion of saturated fats and meat (4)(9)(20) Although there was a decrease in relative total carbohydrate consumption, the consumption of high glycemic carbohydrates increased; consumption of sugar per capita increased steadily from 12.7 kg in 1983 to 30 kg in 2003 (21). A shift toward wider availability and higher consumption of ready-made food has also been seen (17), spurred partly by increased penetration of fast food advertising (9)(22). Increasing urbanization has likely led to a shift away from active, energy-expensive occupations in agriculture to service and manufacturing, resulting in less physical activity (4)(23). Improved mass transit, cheap taxis and motorbikes, and the use of personal vehicles mean that the population does not walk or ride bicycles to commute. Leisure time activities are also less active, due at least partly to the nearly universal ownership of televisions; the proportion of households owning televisions increased from 78% and 39% in urban and rural areas, respectively, in 1990 to almost 90% in both urban and rural areas in 2000 (24).

The contrasting relationship between education and overweight or obesity in women compared with men may be explained partly by social or cultural values. There is increasing social pressure on women to be thin (25)(26), whereas being overweight in Asian men may still be associated with prosperity and wealth. Highly educated women are also likely to be more health conscious, have greater access to health information, and have more choice regarding diet and exercise than lower-educated women (27). Occupations common among lower-educated women in Thailand, such as those in the manufacturing and retail sectors, also tend to involve sedentary tasks and, thus, lower energy expenditure (28), whereas lower-educated men are more likely to be involved in occupations involving physical activity.

Policies and programs to tackle the threat of overweight and obesity have been established, most notably a national public health campaign in 2004, “Healthy Thailand,” which has health promotion components targeting increased physical activity and healthier diets. Given the closing gap between urban and rural areas, the inverse relationship between education and overweight or obesity in women, and the likely future shift in men as economic development continues, it is crucial that these programs adequately cater to those of lower SES who are more constrained in their choices regarding diet and physical activity. This is particularly so for the urban poor who, in addition to these constraints, also have lower energy expenditure patterns than those from rural settings (29). This emphasizes the need for parallel action on environmental change and urban planning that encourages physical activity.

Some limitations of the present analysis should be noted. For the analysis of trends over time, the two cross-sectional surveys did not use the same sampling frame and, thus, may not be strictly comparable. The comparison was also limited to those 18 to 59 years of age. In examining differentials between urban and rural areas, it is also possible that migration from rural to urban areas in Thailand obscures some of the differentials. Another limitation relates to the lack of information on non-responders. Although overall collection rates were generally high, especially for NHES III, data were not available from either survey to allow the assessment of potential non-responder bias.

To our knowledge, this study is the first to demonstrate at a national level the dramatic increase in the prevalence of overweight and obesity and the inverse relationship between education and overweight or obesity in women in Thailand. Although the transition of overweight and obesity to the lower socioeconomic portions of the Thai population is not complete, it is well on its way and can be expected to continue as economic growth persists. This emphasizes to other countries experiencing similar transitions the importance of establishing data collection systems that allow the monitoring of trends in obesity and overweight. For Thailand, these findings indicate the need for further and sustained action at both public and policy levels. Thai policy makers can learn from experiences in countries experiencing similar trends, such as Brazil (30) and China (31). Health education to raise awareness and promote healthier lifestyles should be strengthened and supported by parallel policy and environmental changes. These steps are crucial if Thailand is to avoid the rising health burden of overweight and obesity.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

NHES III was supported by the Bureau of Policy and Strategy, Ministry of Public Health, and conducted by the Health Systems Research Institute, Thailand. Participating individuals in NHES III include: Suwit Wibulpolprasert, Wiput Phoolcharoen, Siriwat Tiptaradol, Yawarat Porapakkham, Porapan Punyaratabandhu, Yongyuth Chaiyapong, and Kasame Vejsutanonth (coordinating team); Bodi Dhanamun, Narin Hiransuthikul, Thosporn Vimolkej, Somrat Lertmaharit, Pornarong Chotiwan, Wiroj Jiamjarasrangsi, Poranee Laoitthi, Mayuri Chiravisit, Sarawuth Urith, andSurasak Taneepanichskul (Chulalongkorn University); Chalermchai Chaikittiporn, Kanda Vathanophas, Chaovayut Phornpimolthape, Rawiwan Sangchai, and Chanya Siengsanor (Mahidol University); Virasakdi Chongsuvivatwong, Mafausis Dueravee, Somsak Vanseng, Arpapak Kiatkittipong, and Siriwan Deawsurintr (Prince of Songkla University); Thanaruk Suwanprapisa, Nongyao Udomvong, Darunee Tayati, Decha Tamdee, and Thanapan Junyasiri (Chiang Mai University); and Pyatat Tatsanavivat, Amorn Premgamone, Somdej Pinijsoontorn, Manop Kanato, Suchada Paileeklee, and Wattana Ditsathaporncharoen (Khon Kaen University). Data analysis was conducted by the Setting Priorities using Information on Cost-Effectiveness project, which is funded by grants from the Wellcome Trust, United Kingdom (Grant 071842/Z/03/Z), and the National Health and Medical Research Council of Australia (Grant 301199). The authors have no competing interests to declare. W.A. and S.S.L. conceived of the research question. M.C.H. wrote the first draft and conducted the statistical analysis with advice from S.S.L. and W.A. W.A. coordinated the research. V.C., P.T., S.C., A.B., and S.T. contributed to data collection. Subsequent revisions were carried out by M.C.H., S.S.L., and W.A. with input from all authors. The final version was approved by all authors.

Footnotes
  • 1

    Nonstandard abbreviations: SES, socioeconomic status; NHES III, Third National Health Examination; NHES II, Second National Health Examination Survey; PPS, probability proportional to size; EU, electoral unit; WC, waist circumference; OR, odds ratio; CI, confidence interval.

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  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References
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