Keywords: obesity, prevalence, body mass index, ethnicity, Turkey.Background and Objectives

Obesity is a health problem that contributes significantly to morbidity as well as overall mortality. The prevalence of obesity in some low income and transitional countries is as high as, or even higher than, the prevalence reported in developed countries, and it seems to be rapidly increasing. In most countries, the prevalence of obesity is higher in women than in men, and in urban than in rural areas.[1]

There is considerable evidence that overweightness and obesity have emerged as epidemics in developed countries since 1980s.[2] This is a matter of concern because overweightness and obesity are major risk factors for several chronic conditions, including coronary heart disease, type 2 diabetes mellitus, hypertension and selected cancers which all cause mortality.[3-7] Mortality due to cardiovascular disease is increased in obese individuals, and the death rate from complications of type 2 diabetes mellitus is extremely high. The strongest evidence that obesity has an adverse effect on health comes from population-based prevalence (cross-sectional) and incidence (longitudinal) studies.[8]

Our study is a cross-sectional study designed to estimate the prevalence of obesity and its determinants in an adult population in Adana, southern province of Turkey in 2003.

Sample
Our population was Adana City population, Turkey. The sample size was calculated from the total population of Adana (n=1.849.478). With the maximum acceptable difference set at 5%, design effect at 2, 3 clusters, estimated true rate of 30 %, and a 95% confidence interval, the required sample size was 648.9

Method
This study is a cross-sectional home based survey. Selection of subjects was performed by random sampling design. Sampling procedure was as follows: Selection performed by random sampling design with the first stage being selection from areas of enumeration districts of the population census and the second stage being identification of dwellings and third stage being selection from three different (low, intermediate and high income) socioeconomic statuses. Each dwelling in the sampling universe had an equal probability of being selected for inclusion in the first stage.

Only 25-65 years old men and non-pregnant women were interviewed by health professionals at home using a questionnaire form. Sociodemographic details, personal and family medical histories were recorded. Anthropometric measurements were performed using the Monica Manual.[10] Nonresponse/refusal rates underwent statistical adjustment by using appropriate sampling weights.

Informed consent was obtained after the nature of the procedures had been fully explained to participants. Ethical approval was obtained from the Ethics Committee of Cukurova University Faculty of Medicine.

Height and Weight
Heights of the participants were measured to the nearest half centimeter. The subject was asked to remove shoes and stand with his/her back to the rule. The back of head, back, buttocks, calves and heels touched the upright. The head was positioned so that the top of the external auditory meatus was in the same level with the inferior margin of the bony orbit. Weight was measured to the nearest tenth of a kilogram. The subject was asked to remove shoes and was lightly dressed only. Obesity was calculated using body mass index (BMI) formula (BMI=weight/height2 [kg/m2]); underweight <18.5 kg/m2; normal=18.5-24.9 kg/m2; overweight=25.0-29.0 kg/m2; obese =30.0 kg/m2.

Waist and Hip Circumference
The subject was asked to stand with feet 12-15 cm apart, weight equally distributed on each leg and to breathe normally. The observer either sat or knelt in front of the subject to place the tape. The waist girth was measured at the mid point between the iliac crest and the lower margin of the ribs. The hip girth was recorded as the maximum circumference around the buttocks posteriorly and anteriorly by the symphysis pubis. Measurements were taken to the nearest 0.5 cm. Waist circumference (WC) ³ 94 cm in males was accepted as overweight, whereas WC ³ 102 cm as obese; (³80 cm and ³ 88 cm in females, respectively). Waist/hip ratio (WHR) =1.0 in males was accepted as overweight, whereas WHR ³ 0.95 as obese; (=0.85 and =0.80 in females, respectively).

Quality Control
All members of the survey team were trained in all measurements. Visual quality control was a continuous part of the field work. Retraining and examining of survey team members were performed on a weekly basis. Completed questionnaires were checked for illegible answers and unanswered questions, before leaving an area.

Data Analysis
Data were analyzed using a statistical package program and Pearson chi square, ANOVA, one-way analysis of variance analysis.

Results
Sociodemographic features of subjects are presented in Table 1. The majority of subjects were elementary school graduates (36.7%). As level of education increased percentage of females decreased (p=0.001). The majority of subjects were married (90.6%). There was no gender difference in marital status except divorced/widowed (92.5% were female). The majority were in low income level (77.3%).

The data reported here suggested that there is a progressive increase in weight, and therefore in BMI, in both men and women up to 50 years of age, with women attaining a higher mean of BMI. The increase is particularly in the 20-29 years of age, amounting to 5-6 kg in men and 6-7 kg in women. The prevalence of underweight, overweight and obesity is presented in Table 2. Of 900 subjects, 38.3% were overweight and 26.6% were obese.

Our study showed that there may be no significant relationship between ethnicity and obesity (p>0.05) (Table2).

Prevalence of obesity
The majority of the subjects tend to be in the overweight group (38.3%). Obesity was more frequent in married subjects than not married ones (p=0.001), in subjects with low socioeconomic status than ones with higher socioeconomic status (p=0.002). Obesity was higher in subjects with older age till 55-65 years of age. In 55-65 years of age rate of obesity decreased. There was a significant relationship between obesity and age groups (p=0.001). Obesity was higher in subjects with lower educational status (p=0.001) (Table 2). According to waist circumference (WC), the majority was in the normal group (48.3%), obese people were in the second rank with 31.8% and overweight were 19.9%. The percentages according to WHR were 58.0% and 42.0% for the normal and obese people, respectively, (Table 3).

Obesity was more frequent in females than males according to BMI, waist circumference and WHR (p=0.001) (Table 3). The majority of women in our study group had 3-4 pregnancies on average. Obesity was more frequent in women with higher number of pregnancies than ones with lower number of pregnancies according to BMI (p=0.001) (Table 4).

Discussion
Obesity is a common chronic disease in Western societies. The prevalence of obesity and overweight is progressively increasing in the developed countries.[11,12] It is estimated that there are 250 million people with BMI =30 in the world which is 7% of the world population.[13]

Turkey has been experiencing a rapid phase of industrialization and urbanization in recent decades and has often been recognized as a role model for developing economies. The 'westernization' of global eating habits has also brought about an increase in the number of fast-food outlets in Turkey during the last decade.14 Obesity and overweight are increasing in Turkey (TEKHARF 1990 and 2000).[15] The overall prevalence of obesity in adults was 18.6% in year 1990. Ten years later in 2000, the prevalence was 21.9%, which shows a relative increase rate of 17.7%. As it is true for most of the countries, overweight is more common in men and obesity in women in Turkey.[15]

Obesity prevalence is 6-20% in males and 6-30% in females in Europe.16 The highest rates are in the East (Russia, former East Germany and Republic of Czech) and the lowest in Central Europe and Mediterranean countries. Rates of North America are similar to Europe, 20% of males and 25% of females in the United States of America (USA) are obese whereas 15% of adult population in Canada is obese. Prevalence of obesity is 15-18% in Australia and New Zealand. Japan as an industrialized country has a very low rate of obesity (less than 3%).16

In this study, it is possible that the same factors affect obesity, including older age, female gender, lower educational and socioeconomic status, and high number of pregnancies. Increasing age is widely accepted as a predisposing factor for obesity. As the individual gets older, the metabolic rate slows down. Besides, the inclination for daily exercise decreases dramatically.

The results of this survey show a steady, but significant, decline in both BMI and WHR in people with higher educational status. Those people with higher socioeconomic status are able to afford fitness activities and are also able to appreciate and implement the health advertisements in media.

Our data suggests that obesity is a serious problem in Adana. The obesity prevalence is higher in urban than in rural regions, and in females than males. The prevalence of overweight is higher in males than females and it is higher than the rate for overall Turkey. The prevalence of obesity is higher in urban males and females at every socioeconomic status, except for urban females with high socioeconomic status. Rural-to-urban migration and rapid urban growth are elements of epidemiological transition. Progressive urbanization and mass media may contribute to the shift in diet of rural migrants who abandon their typical rich-in-vegetables- and-cereal diets in favor of those high in processed and animal food. This change of diet is accompanied with reduced levels of physical activity resulting in overweightness and obesity.

In our study, obesity measured by WHR was found to be higher than obesity measured by BMI and WC. The reason may be due to comprehensiveness of WHR including android type of obesity. It is well known that cardiovascular diseases are more frequent in android type obesity. According to WHO MONICA data, the measurements only by WC, WHR or BMI show variations in different countries.[17]

Prevalence of obesity measured by WC is higher than prevalence of obesity measured by BMI which may be due to including subjects with abdominal obesity. Our results are similar to those of 19 countries in WHO MONICA study phase 2 (1987-1992) (WC=102 cm in males, =88 cm in females).[17,18]

The ethnic profile of Adana population is as follows: The population of Adana is a mix of the Turks who arrived about 900 years ago, Eti Turks and Kurds, both groups migrated from Syria over 1200 years ago. The population shares a social and cultural identity together more than 1000 years old. Most marriages in Adana were consanguineous. This inbreeding has also limited the intermingling of cultures, and has contributed to the relatively well-preserved sociocultural and familial identity of each ethnic subgroup, despite residence in the same geographical location.[19,20] Although all ethnic groups in Adana represent relatively discrete populations with distinct historical and geographical backgrounds no significant relationship was detected between ethnicity and obesity of the groups. Perhaps this was the most interesting finding of our study.

Limitations
It should be noted that this study has primarily been concerned with the prevalence of Adana and suffers from a number of limitations. First, census data we used has little correlation with a true balance of society and there is a bias against lower socio-economic status or ethnicity from the fact that they may be homeless or fail to be recorded on the census. Secondly, as our aim in this study was to show only the prevalence of obesity in Adana City, we are planning to perform a future study about people with BMI <18.5 kg/m2 and between 25-29 kg/m2 and the contributing nutritional factors and third, we would like to point out that we have not explored a potential "gene dosage" influence versus environment.

Conclusions
The epidemiological and experimental data show that weight reduction is one of the most beneficial lifestyle changes that can be undertaken by obese patients. Few obese patients will ever achieve their cosmetic 'ideal'; however hard they work to lose weight. However, they can truthfully be told that a modest reduction in body weight is likely to help them live longer and remain in better health. Many physicians regard the management of obesity as an uphill and unrewarding struggle. Obese patients attending chronic disease clinics are routinely advised to lose weight, but there is often little expectation that the advice given will be accepted or acted upon.

Pharmacological treatment of obesity is still regarded with skepticism, here in Adana. Medical practitioners are very concerned about the deleterious side effects (real or imagined). Anti-obesity drug use is restricted to patients with BMI=30 kg/m2. The consideration is given for patients with BMI<30 kg/m2 having significant comorbidities. However, the first-line strategy for weight reduction and weight maintenance is a combination of diet, exercise and behavior modification. This pattern of treatment seems to be keeping with what is practiced in the United Kingdom.[21] There is therefore much educational work to be performed. The energy-deficient diet, combined with appropriate exercise, will remain the cornerstone of most weight reduction programs, here in Adana. However, we may not neglect other possibilities.

The recent WHO report noted that the optimum fat intake for preventing weight gain was probably only 20-25%.[13] This contrasts with the usual advice for the prevention of cardiovascular disease where the emphasis is on the fatty acid content of the diet, with a 30% total fat value being a pragmatically derived goal as part of the need to limit saturated fatty acid intakes. Clearly there is a need for a national strategy to tackle contributors of excess weight gain of Turkish population and we would like to suggest the need for a larger scale study of obesity prevalence.

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