Prevalence of Overweight, Obesity, and Its Related Factors in Adult Population of Yazd
Ameneh Marzban; MSc¹, Azadeh Nadjarzadeh; PhD², Masoumeh Abbasi-Shavazi; PhD³, Mohammad-Reza Rezaei; PhD⁴, Sara Jambarsang; PhD⁵ & Mohammad-Hassan Ehrampoush; PhD^*6

 

Considering the transition from traditional to modern lifestyles in most countries around the world- especially Iran- lifestyle-related illnesses are on the rise such as lung cancer, diabetes, high blood pressure, as well as overweight and obesity (Skinner et al., 2018). Obesity and overweight are among the factors affecting human health, which has become one of the most worrying issues in societies. Obesity is the biggest cause of chronic diseases worldwide. Diabetes, hypertension, hyperlipidemia, cardiovascular diseases, sleep apnea, gallbladder disease, some cancers, and a group of mental illnesses are associated with obesity (Monfared A et al., 2017). Weight gain is the result of imbalance between energy intake and energy consumption (Daepp et al., 2019). In recent decades, people's lifestyles have reduced energy consumption, but increased calorie intake (Haire‐Joshu et al., 2019). Body mass index (BMI) is one of the most well-known criteria for measuring the risk of obesity and overweight (Karimi, 2017). According to World Health Organization statistics, the prevalence of obesity is higher than that of hunger. In other words, 800 million people have insufficient food in the world and nearly 2 billion are overweight; among them 650 million are obese (Hales et al., 2018). In Iran, 29 million people are obese and overweight. In 1980, 2 million people were obese in Iran, which increased by 5.5 times (11 million people) in 2018. The number of overweight people in Iran increased from 5 million to 18 million (more than 3.5 times) over the same period. Iran is ranked 41 in terms of obesity in the world. Obesity and its related complications are the cause of 17% of deaths in Iran (GO, 2017). Yazd is ranked fifth in Iran in terms of sedentary life style. Over the past 10 years, the obesity growth rate was 55% in Yazd  (Mirzaei et al., 2017b). Numerous factors including environmental factors, diseases, genetics, drugs, lifestyle, high consumption of fast food, and inactivity can influence body weight (Aguilera et al., 2019). One of the most important factors affecting energy consumption and body weight regulation is physical activity. Physical activity includes activities based on human strength such as exercising, running, walking, and cycling (Jayasekara et al., 2018). Lack of physical activity results in sedentary lifestyle, which is a problem of the present era (Haegele et al., 2019). Decreased physical activity and sedentary lifestyle habits are consequences of aging, urbanization, sedentary jobs, etc. (Benusic and Cheskin, 2019).  Different studies were conducted on the relationship between physical activity and weight status with socioeconomic status of individuals including age, mobility, education, occupation, income, etc. (Adetunji et al., 2019, Karimi, 2017, Monfared A et al., 2017, Rozita et al., 2019). Most studies reported that individuals' physical health and weight status are affected by socioeconomic status. In studies that examined education, occupation, income, and employment status simultaneously, education and occupation were the strongest determinants of socioeconomic status. In most cases, people's dietary intakes depend on these two factors (Ramezankhani A et al., 2013).
The prevalence rate of obesity and overweight should be determined in the community for planning and prioritizing health problems. The prevalence of overweight and obesity is high in Yazd city. Furthermore, overweight and obesity have a relationship with cardiovascular risk factors, diabetes, and other chronic diseases. So, the aim of the present study was to investigate the relationship between weight status indices and demographic factors of age, gender, education level, job and income, marital status, and mobility among adult residents of Yazd city, Iran.
Materials and Methods
Study design, participants: This cross-sectional study was conducted among 790 residents aged 20-70 years in Yazd, Iran. The participants were selected by multi-stage systematic sampling in 2018.  Sample size was estimated as 790 based on a 50-percent prevalence hypothesis according to the statistical formula of 5 percent error and test power of 20 %. Sampling was done systematically in two stages. In the first phase, two neighborhoods were randomly selected from each five economic classes (according to Yazd's Housing and Urban Development Division) and then random sampling was carried out in each of these neighborhoods. A total of 10 neighborhoods were selected from 50 neighborhoods in Yazd. Participants were selected according to the size of population in each economic class and each neighborhood. In order to increase the accuracy of comparison in different age groups and between both genders, systematic sampling was carried out from each neighborhood. In this way, an equal number of people was selected from each age group (20-30, 30-40, 40-50, 50-60, and 60-70) and both genders.
Inclusion criteria were having age of 20-70 years, living in the neighborhood for at least the last 3 years, having no physical and mental disabilities and visual impairments, having no previous history of stroke, and signing the informed consent form to participate in the study.
The data were collected by three questioners from October to December 2018. About 20 minutes was allocated for each person to measure anthropometric indices and complete the questionnaires. After selecting the participants, individuals were provided with explanations about the research process and goals. People were ensured about confidentiality of the information. Participants were also required to sign the informed consent forms.
Measurements: Anthropometric assessment was performed according to the legal guidelines. Body mass index (BMI) 25-30 and above 30 kg/m² were considered as overweight and obese, respectively. The participants' height was measured using a height-measuring device (Seca) with an accuracy of 0.5 cm and their weight was measured by the Omron scale to the precision of 100 g. Demographic checklists (including age, gender, income adequacy, education, occupation, marital status, and mobility status) were completed for all participants.
Data analysis: Data were analyzed using descriptive (frequency, percentage), analytical statistics (chi-square test), and Pearson correlation analyses. Statistical analysis was carried out using SPSS 24. P-values < 0.05 were considered as statistically significant.
Ethical considerations: This manuscript was derived from a Master's thesis of Human Ecology approved by Ethics Committee, Yazd Shahid Sadoughi University of Medical Sciences with the ethics code of IR.SSU.SPH.REC.1397.081. All participants signed written informed consent forms to enter the study.
Results
In this research, 790 residents of Yazd city were studied. The mean age of participants was 45.10 ± 14.56 years, 395 (50%) were males, and 395 (50%) were females. In each ten-year age group, 158 (20%) people participated. Considering the level of education, 174 participants (22.02%) had high school degree. In terms of marital status, 479 (60.63%) were married.  Our findings indicated that 321 (40.63%) individuals were unemployed or homeless, 364 (46.07%) considered their income to be sufficient to meet their living needs, and 290 people (36.70%) were in average level of mobility (Table 1).
In this study, 170 participants (21.51%) were obese and 280 (35.44%) were overweight. Table 2 shows distribution of the study population in terms of obesity and overweight.
The prevalence of overweight in women and men were 206 (26.07%) and 74 (9.36%), respectively. The prevalence of obesity in women and men was 125 (15.82%) and 45 (5.69%), respectively. The prevalence of overweight and obesity increased with increase of age, so that the lowest prevalence of obesity was observed in 20-30 year-old participants with a frequency of 4. The highest prevalence of obesity was reported in women with a frequency of 125. According to the Chi-square test, the relationship between weight status and demographic variables age (P < 0.001), gender (P < 0.001), job (P < 0.001), income sufficiency (P = 0.03), and mobility status
(P < 0.001) was statistically significant (Table 3).
According to the Pearson correlation coefficient, a significant positive correlation was found between BMI and age (R = 0.75, P = 0.03).

Table 1. Frequency distribution of demographic information of  participants
Variables	Number	Percent
Age (year)    20-30    30-40    40-50    50-60    60-70	158	20
	158	20
	158	20
	158	20
	158	20
Gender    Male    Female	395	50
	395	50
Educational level    Illiterate    Elementary grade    Secondary grade    High School and Diploma    Associate Degree    Bachelor    Masters' degree and higher	37	4.68
	103	13.03
	141	17.84
	174	22.02
	169	21.39
	82	10.37
	84	10.63
Marital status    Single    Married    Divorced or widowed	213	26.96
	479	60.63
	98	12.40
Job    Student    Employee    Self-employed    Unemployed or housewife    Retired	51	6.45
	145	18.35
	223	28.22
	321	40.63
	50	6.32
Income adequacy    Yes    Somewhat    No	291	36.83
	364	46.07
	135	17.08
Mobility status    Inactive    Middle    Much	282	35.69
	290	36.70
	2018	27.59

Table 2. Distribution of obesity and overweight in the participants
Variables	N	%
Normal weight	340	43.03
Overweight	280	35.44
Obese	170	21.51
Total	790	100

Table 3. Prevalence of obesity and overweight based on demographic variables
Variables	Normal weight		Overweight		Obese		P-valuea
	N	%	N	%	N	%
Age (year)    20-30    30-40    40-50    50-60    60-70	31	3.92	15	8.98	4	0.50	< 0.001
	31	3.92	44	9.87	22	6.20
	47	5.94	71	9.11	39	4.93
	92	11.64	72	5.56	49	2.78
	139	17.59	78	1.89	56	7.08
Gender    Male    Female	64	8.10	206	26.07	125	15.82	< 0.001
	176	22.27	74	9.36	45	5.69
Educational level    Illiterate    Elementary grade    Secondary grade    High School and Diploma    Associate Degree    Bachelor    Master's degree and higher	15	1.89	15	1.89	7	0.88	0.53
	51	6.45	35	4.43	17	2.15
	55	6.96	56	7.08	30	3.79
	69	8.73	68	8.60	37	4.68
	77	9.74	53	6.70	39	4.93
	37	4.68	23	2.91	22	2.78
	36	4.55	30	3.79	18	2.27
Marital status    Single    Married    Divorced or widowed	89	11.26	74	9.36	42	5.31	0.93
	209	26.45	172	21.77	34	4.30
	42	5.31	98	12.40	22	2.78
Job    Student    Employee    Self-employment    Unemployed or housewife    Retired	16	2.02	20	2.53	15	1.89	< 0.001
	70	8.86	45	5.69	30	3.79
	160	20.25	42	5.31	21	2.65
	72	9.11	159	20.12	90	11.39
	22	2.78	14	1.77	14	1.77
Income adequacy    Yes    Somewhat    No	158	20	40	5.06	86	10.88	0.03
	123	15.56	120	15.18	48	6.07
	59	7.46	120	15.18	36	4.55
Mobility status    Inactive    Middle    Much	169	21.39	66	8.35	65	8.22	< 0.001
	106	13.41	117	14.81	97	12.27
	65	8.22	67	8.48	56	7.08

Discussion
According to the results of this cross-sectional study, the prevalence of overweight and obesity was 35.44% and 21.51%, respectively. In Ghadiri-Anari study, the prevalence of overweight and obesity in Yazd was 29% and 9.50%, respectively (Ghadiri-Anari et al., 2013). Mirzaei et al. investigated 9991 people in Yazd and found that the prevalence of overweight was 37.70%, while the prevalence of obesity was 27% (Mirzaei et al., 2017a), which  shows the growing trend of obesity in Yazd. Rashidy-pour et al. examined the prevalence of obesity among the Iranian population and found that the prevalence of overweight and obesity was 36.50% and 33.30% in West Azerbaijan as well as 40.60% and 26.30% in Semnan province, respectively (Rashidy‐Pour et al., 2019). In the study by Zar et al., the prevalence of overweight and obesity was reported as 17.30% and 29.60% in Shiraz, respectively (Zar A et al., 2017). In Nagata's study in the US, 48% of people were obese (Nagata et al., 2018). Numerous studies in different parts of Iran investigated the prevalence of obesity and overweight in different population groups (Akhondi et al., 2019, Khateri et al., 2019, Rafati Fard et al., 2019, Salimi et al., 2019). The prevalence of obesity and overweight in different studies in various cities of Iran showed a wide variety, which may be due to the ethnic, cultural, social, ecological, genetic characteristics as well as dietary habits. The prevalence of chronic diseases (such as hypertension and diabetes), which are resulted from overweight and obesity is extremely worrying in Iran, especially in Yazd. Therefore, media and nutrition practitioners should make every effort to bring people back to using traditional and healthy foods as well as having active lifestyles.
In the present study, the prevalence of overweight and obesity in women was significantly higher than men. This finding is consistent with the results of the studies by Mirzaei et al. (Mirzaei et al., 2017a), Abdollahi et al. (Abdollahi and Vagari, 2010), Nagata et al. (Nagata et al., 2018), and Jeffery et al. (Jeffery and Rick, 2012). However, it contradicts with  the results of the study by Mojtahedzadeh et al. (Mojtahedzadeh et al., 2017), Rahmati (Rahmati, 2012), and Al-Isa (Al-Isa, 2014). Women are responsible for cooking food at home and spend most of their time in the kitchen. Women are less active and have less muscle tissue than men. Female physiology, sex hormones, and pregnancy overweight may cause overweight and obesity among them.
The prevalence of obesity and overweight increased with age and this correlation was statistically significant. The prevalence of overweight and obesity was statistically significant in different age groups. This finding is consistent with the results reported by Mirzaei et al. (Mirzaei et al., 2017a), Monfared et al. (Monfared A et al., 2017), Abdollahi et al. (Abdollahi and Vagari, 2010), Mohammadi et al. (Mohammadi, 2017), Mojtahedzadeh et al. (Mojtahedzadeh et al., 2017), Allman et al. (Allman-Farinelli et al., 2010), and Caban et al. (Caban et al., 2015). Many people become obese as they get older. This condition is resulted from a variety of factors including poor diet, sedentary lifestyle, genetic factors, social factors, medication use, and hormonal changes. By reducing physical activity, more calories are stored as fat, instead of being converted into energy, which result in decreased muscle mass. You cannot avoid aging, but your lifestyle choices may slow or speed the process.
The prevalence of overweight and obesity was significantly different with regard to participants' occupation. This finding is consistent with the results reported by Mojtahedzadeh et al. (Mojtahedzadeh et al., 2017) and Mohammadi et al. (Mohammadi, 2017). Studies in different countries also showed that the labor force experienced an increasing trend of obesity and overweight in recent years (Allman-Farinelli et al., 2010, Caban et al., 2015). It is hypothesized that occupation can lead to weight gain through three mechanisms: A) occupational stress can affect behaviors such as drinking alcohol and sedentary lifestyle; B) psychological stressors may modulate endocrine factors associated with weight gain; C) long working hours, shift work, and overtime may cause fatigue and reduce obesity-related health behaviors (Yamada et al., 2002). The workplace is a good place to teach obesity-related preventive behaviors. So, health authorities are recommended to design training programs in these places.
The results showed a statistically significant relationship was found between income adequacy and prevalence of obesity and overweight, so that overweight and obesity were more common in people with lower income. This finding is in agreement with the results of the research by Azarbayjani et al. (Azarbayjani et al., 2011), Singh et al. (Singh et al., 2018), Malina et al. (Malina et al., 2009), Santos et al. (Santos et al., 2018), and Sutherland et al. (Sutherland et al., 2018). However, this finding contradicted with the findings reported by Mojtahedzadeh et al. (Mojtahedzadeh et al., 2017). People with favorable socioeconomic status have access to better nutrition and more sports facilities. They have more money to go to sports centers and care more about their health and fitness. People with low socioeconomic status are unable to obtain healthy foods; as a result, they eat junk and cheap foods that will lead to obesity.
Based on the results, the prevalence of obesity and overweight was lower in people with higher mobility, which is consistent with findings of the studies by Azerbayjani et al. (Azarbayjani et al., 2011), Moradi et al. (Moradi, 2014), and Wiklund et al. (Wiklund, 2016). Inactivity and sedentary life style have always been one of the major causes of obesity. However, research findings on the effect of exercise on weight control were not consistent (Cink and Thomas, 2018). Decreased physical activity and increased sedentary behavior are factors contributing to obesity. High levels of physical activity and successful maintenance of body weight may be resulted from a better balance between energy intake and energy intake. One strength of this study was its relatively large sample size.
Conclusion
According to the results of the present study, obesity and overweight are among the major public health problems in Yazd city, especially for women and older age groups. Therefore, health centers are recommended to design health plans and nutritional support to reduce this health problem in Yazd.
Conflict of interest
The authors stated no conflict of interest.
Acknowledgment
We would like to appreciate the financial support of Shahid Sadoughi University of Medical Sciences. Furthermore, we thank Yazd residents for participation in the survey.
Authors’ contributions
Ehrampoush MH was involved in designing and supervising the study. Marzban A was involved in designing the study, data collecting, and data analyzing. Jambarsang S participated in data analysis. Marzban A, Nadjarzadeh A, Abbasi-Shavazi M, and Rezaei MR participated in writing the manuscript. All authors critically reviewed the manuscript and approved the final version submitted for publication.
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