Overweight and Obesity: Findings from 20 Years of the Tehran Lipid and Glucose Study

Prevalence of obesity and overweight in an adult population of Tehran metropolis

Purpose

Obesity is a chronic low-grade inflammatory condition with increasing global prevalence and is associated with cardiovascular diseases. In this study, we aimed to investigate the prevalence of obesity in the Tehran cohort study (TeCS) population.

Methods

We used the data collected by systematic random sampling during the recruitment phase of TeCS. The data comprised 4215 households from all districts of the Tehran metropolis, from which 8296 adults aged ≥ 35 years participated between May 2016 and February 2019. Sociodemographic data, medical history, laboratory tests, and anthropometric measurements were gathered from the participants. Participants with missing data were excluded from the final analysis. Finally, the data was analyzed using SPSS version 23, and distribution maps were created by Stata 14.2.

Results

A total of 8211 participants (53.9% women) with an average age of 53.7 ± 12.6 years were studied. The age-weighted prevalence of overweight and obese among women was (37.5% [95% confidence interval (CI): 34.5, 40.6] and 35.5% [95% CI: 32.6 -38.6]) compared to men (47% [95% CI: 43.6, 50.3] and 22.9% [95% CI: 20.1 -25.8]). The prevalence of substantially increased risk of metabolic complications (SIRMC) based on waist circumference (WC) and waist-to-hip ratio (WHR) was 49.2% (95% CI: 46.3 -52.2) and 75.5% (95% CI: 72.7 -78.1) respectively.

Conclusions

The prevalence of obesity in Tehran (29.3%) was much higher than in previous reports, particularly among older people, women, and socioeconomically underdeveloped districts. After age 55, more than 80% of women had SIRMC compared to 30% of men.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01365-4.

Setting and prioritizing evidence-informed policies to control childhood obesity in Iran: a mixed Delphi and policy dialogue approach

BACKGROUND

The prevalence of childhood obesity (CO) and related complications is high and alarmingly increasing in Iran. This study applied a mixed Delphi & Policy Dialogue approach to exploring and prioritizing policy options to control childhood obesity in Iran.

METHODS

This study is organized in three Delphi phases followed by a policy dialogue session. This study applied the advocacy collation framework and evidence-informed policy-making approach to enhance the chance of a feasible and acceptable policy package. The first step consisted of interviews with 30 experts and primary stakeholders. Based on their answers and a comprehensive literature review, a list of presumed effective policy options to combat CO in Iran was made. Then, panelists were asked to score each policy option using a five-point Likert scale in seven constructs. To maximize the spread of opinions, panelists were chosen to represent three perspectives: policy-makers at different levels, presidents of various organizations who would implement potential policy options, and academics. Twenty-one stakeholders were invited to discuss the policy options in a policy dialogue section.

RESULTS

We introduced 27 policy options and asked stakeholders to rank them using seven criteria on a five-level Likert scale. Totally, 41 experts participated in round 2 (66.2% response rate), and 33 experts took part in round 3 (72% response rate). Participants believed that healthy schools, creating healthy environments in kindergartens and other child care centers, subsidizing healthy foods, educating healthy lifestyles in mass media, and increasing access to physical activity facilities are the most effective and feasible policies in controlling CO. After the policy dialogue, the healthy school remained the most prioritized policy. a policy package to combat CO in Iran was designed with the participation of all stakeholders.

CONCLUSION

The advocacy collation framework and the evidence-informed policy-making approach were used to draft a policy package to combat CO, increasing the acceptability and feasibility of the developed policy package.

Efficacy of low-fat milk and yogurt fortified with vitamin D3 on systemic inflammation in adults with abdominal obesity

Background

The prevalence of vitamin D deficiency is increasing globally and is associated with an increased risk of metabolic syndrome, autoimmune disease, and cardiovascular disease. Vit D deficiency is also associated with increased systemic inflammation. The current study aimed to determine the efficacy of low-fat milk and yogurt fortified with 1500 IU nano-encapsulated vitamin D, on systemic inflammation in abdominal obese participants.

Method

This multi-center study was conducted using a 2.5-month parallel total-blind randomized clinical trial design. Two hundred and eighty nine subjects were allocated to four groups: low-fat milk fortified by 1500 IU nano-encapsulated vitamin D₃ (200 mL/day). Simple milk (200 mL/day), low-fat yogurt fortified by 1500 IU nano-encapsulated vitamin D₃ (150 g/day), and simple yogurt (150 g/day).

Results

The results showed that serum levels of neutrophils, lymphocytes, platelets and red blood cell distribution width (RDW) were significantly lower before and after the intervention in fortified dairy groups. The results showed that serum levels of neutrophils, lymphocytes, platelets, and RDW before and after intervention in the fortified dairy groups were significantly lower (p < 0.05). The values of = neutrophil to lymphocyte ratio (NLR), platelets to lymphocyte ratio, and RDW to platelets ratio (RPR) reduced significantly in the fortification group (p < 0.05).

Conclusion

Fortification with nano-encapsulated vitamin D₃ of dairy products may decrease inflammation in individuals with abdominal obesity.

The association of the age, period, and birth cohort with 15-year changes in body mass index and waist circumference in adults: Tehran lipid and glucose study (TLGS)

Objective

To examine the association of age, period, and birth cohort with body mass index (BMI) and waist circumference (WC) changes among the participants of the Tehran Lipid and Glucose Study from 1999 to 2015.

Methods

This prospective cohort study included 4895 participants aged ≥20 years (41.3% men), who were divided into twelve gender stratified groups, having a ten-year age difference between them. Analyses were conducted to explicitly assess the association of age vs. period on BMI and WC changes. In addition, we evaluated BMI and WC changes among different birth cohorts.

Results

Upon 15 years of follow-up, the mean BMI of men and women increased from 26.0 ± 3.9 to 27.5 ± 4.3 kg/m² and from 27.5 ± 4.8 to 29.9 ± 5.4 kg/m² (P trend < 0.001), and this trend was accompanied by an increase in WC from 88.8 ± 10.9 to 97.8 ± 10.4 cm and from 87.3 ± 12.4 to 95.8 ± 12.1 cm, respectively (P trend < 0.001). Men and women in all age cohorts tended to have a rise in their BMI and WC with aging throughout the follow-up period. For men, this trend was more prominent in younger birth cohorts at phase III for BMI and at phases III and V for WC (indicating a significant negative association with birth cohort). For women, this trend was more prominent in older birth cohorts at both phases III and V for BMI and WC (indicating a significant positive association with the birth cohort).

Conclusion

The rise in BMI and WC was strongly associated with age in both sexes. The men born in the recent birth cohorts and the women born in earlier birth cohorts had the most alarming BMI and WC trends. More efforts must be spent on obesity prevention policies, especially for younger men.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12810-z.

Impact of Telenursing on Blood Pressure and Body Mass Index of People with Prehypertension: A Randomized Controlled Clinical Trial

BACKGROUND

Prehypertension is an important global health challenge. This study determines the effect of telenursing on Blood Pressure (BP) and Body Mass Index (BMI) in patients with prehypertension.

MATERIALS AND METHODS

This randomized controlled clinical trial study included 81 patients with prehypertension discharged from an emergency room at Isfahan University of Medical Sciences (Iran) in 2016. Participants joined a session about hypertension, risk factors, and lifestyle modification to reduce its risk. Using a random number table, 41 subjects were assigned to the experimental group and 40 subjects to the control group. Only the experimental group received four SMS messages each week and a 10-15 min phone call once a month to help them change their lifestyle and reinforce their health behaviors. Eventually, patients' information was collected, and the data were analyzed using independent t, paired t, and Chi-square tests.

RESULTS

The experimental group after the intervention had a significantly lower mean (Standard Deviation [SD]) of Systolic Blood Pressure (SBP) (from 126.67 [5.15] to 119.21 [5.72] [t 40 = 8.40, p < 0.001]) and Diastolic Blood Pressure (DBP) [from 85.28 (2.29) to 78.79 (4.16) (t 40 = 10.02, p < 0.001)]. However, the same means were not significantly different in the control group [SBP (p = 0.116) and DBP (p = 0.096)]. The mean (SD) of changes between BMI before and after the intervention was -0.75 (0.66) in the experimental and 0.042 (0.41) in the control group, which was significantly different between the two groups (t 79= -6.44, p < 0.001).

CONCLUSIONS

Telenursing can have potential benefits to maintain BP within the normal range and reduce BMI in patients with prehypertension.

Prevalence of hypertension and related risk factors in central Iran: Results from Yazd Health Study

BACKGROUND

The prevalence of hypertension (HTN) varies across countries due to differences in its related risk factors. This study aimed to investigate the prevalence of HTN and related risk factors among adults.

METHODS

This study was conducted on the data from the recruitment phase of Yazd Health Study. Using multi-stage random cluster sampling, 10000 adults of 20-69 years were selected. Self-reported HTN (diagnosed by a physician) was recorded in a home visit. Blood pressure (BP) was measured using a standard protocol and categorized based on the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and ýTreatment of High Blood Pressure (JNC-7) classification. T-test was used to examine the gender differences. Qualitative variables were presented as number (frequency). Chi-square test and bivariate logistic regression were carried out to determine the association between risk factors.

RESULTS

The response rate was 95% (n = 9975). The prevalence of positive history of HTN was 18.5%. The mean systolic and diastolic BP was 126.5 ± 18.4 and 80.2 ± 12.5 mmHg, respectively. The prevalence of HTN was 36.0% (95%CI: 35.1-36.9). Its prevalence reduced by high-education, physical activity, lower BMI, and lack of history of diabetes mellitus (DM) (P < 0.0001). HTN is less common in smokers (P < 0.0001). Logistic regression analysis showed that HTN was higher among men (OR: 1.83; 95%CI: 1.64-2.03), the elderly (OR: 5.15; 95%CI: 4.20-6.31), low-educated (OR: 1.40; 95%CI: 1.17-1.67), and diabetics (OR: 1.20; 95%CI: 1.05-1.38). The prevalence of HTN was 2 times higher in obeses. HTN did not have a significant relationship with inactivity, smoking, and hypercholesterolemia.

CONCLUSION

The prevalence of HTN was high. By identifying modifiable risk factors, health policymakers can prioritize intervention programs. It is necessary to inform younger adult groups how these factors can be managed through a healthy lifestyle and nutritional habits.

Gender difference in determinant factors of being overweight among the 40-70-year-old population of Kharameh cohort study, Iran

Background

Iranians face being overweight as one of the most common health problems, which is more prevalent among women. This study aimed to identify gender differences in determinants of being overweight in 40- to 70-year-old participants from Kharameh, Iran.

Methods

This cross-sectional study was conducted during 2015–2016. The total 10,663 inhabitants of Kharameh, Iran, aged 40–70 years old, were target population. Those with a body mass index (BMI) < 18.5 or > 29.9 were excluded. A checklist composed of socio-demographic, lifestyle, and BMI items was used; a p-value < 0.05 was considered significant.

Results

Overall, 53.4% of 8222 participants were overweight. The prevalence of overweight women (62.7%) was significantly higher (p <  0.001) than men (43.6%).

The logistic regression model for men showed that being overweight was more likely among men with cigarette smoking history (OR = 1.49) and those with a moderate physical activity level (OR = 1.35), but less likely among those with a higher socio-economic status (SES) (OR = 0.74). Among women, being overweight was associated with high SES (OR = 1.61), an education level below high school diploma (OR = 1.57) and primary school education (OR = 1.50), being married (OR = 2.39), widowed (OR = 2.11) and having a greater calorie intake (OR = 1.01). Being overweight was less likely among employed women (OR = 0.85), those with cigarette smoking history (OR = 0.65), and those with high (OR = 0.72) and intensive physical activity (OR = 0.73).

Conclusions

This study revealed the gender differences in determining factors affecting being overweight. As being overweight was more prevalent among women, the priority of health policies to control this issue should also be focused on women.

Iranian Endocrine Society Guidelines for Screening, Diagnosis, and Management of Gestational Diabetes Mellitus

CONTEXT

Gestational diabetes mellitus (GDM) is an important endocrine disorder in perinatology, associated with several maternal and neonatal complications. Development of national guidelines can inform clinicians, health policymakers, and researchers about the most recent evidence and practical issues of diagnosis and management of GDM.

OBJECTIVES

We aimed to develop clinical practice guidelines for the diagnosis and management of GDM in Iranian pregnant women.

EVIDENCE ACQUISITION

The Iranian Endocrine Society constituted a task force, consisting of obstetrician-gynecologists, endocrinologists, a clinical nutritionist, a clinical epidemiologist, and a librarian, to review the published literature and propose national guidelines for the diagnosis and management of GDM. The consensus was reached on all recommendations in several group meetings with a majority decision. The evidence and recommendations were graded according to the American College of Physicians' Guideline Grading System.

RESULTS

The proposed guidelines included recommendations for screening, diagnosis, and management of GDM in Iran.

CONCLUSIONS

By using an evidence-based approach, these national GDM guidelines can address important clinical issues in the diagnosis and management of Iranian women with GDM.

Sex-specific prevalence of coronary heart disease among Tehranian adult population across different glycemic status: Tehran lipid and glucose study, 2008-2011

Background

Coronary heart disease (CHD) is one of the leading causes of death. Alarmingly Iranian populations had a high rank of CHD worldwide. The current study aimed to assess the prevalence of CHD across different glycemic categories.

Methods

This study was conducted on 7718 Tehranian participants (Men = 3427) aged ≥30 years from 2008 to 2011. They were categorized based on glycemic status. The prevalence of CHD was calculated in each group separately. CHD was defined as hospital records adjudicated by an outcome committee. The association of different glycemic categories with CHD was calculated using multivariate logistic regression, compared with normal fasting glucose /normal glucose tolerance (NFG/NGT) group as reference.

Results

The age-standardized prevalence of isolated impaired fasting glucose (iIFG), isolated impaired glucose tolerance (iIGT), both impaired fasting glucose and impaired glucose tolerance (IFG/IGT), newly diagnosed diabetes mellitus (NDM), and known diabetes mellitus (KDM) were 14.30% [95% confidence interval (CI): 13.50–15.09], 4.81% [4.32–5.29], 5.19% [4.71–5.67], 5.79% [5.29–6.28] and 7.72% [7.17–8.27], respectively.

Among a total of 750 individuals diagnosed as cases of CHD (398 in men), 117 (15.6%), 453 (60.4%), and 317 (42.3%) individuals had a history of myocardial infarction (MI), cardiac procedure, and unstable angina, respectively. The age-standardized prevalence of CHD for the Tehranian population was 7.71% [7.18–8.24] in the total population, 8.62 [7.81–9.44] in men and 7.19 [6.46–7.93] in women. Moreover, among diabetic participants, the age-standardized prevalence of CHD was 13.10 [9.83–16.38] in men and 10.67 [8.90–12.44] in women, significantly higher than corresponding values for NFG/NGT and prediabetic groups.

Across six levels of glycemic status, CHD was associated with IFG/IGT [odds ratio (OR) and 95% CI: 1.38 (1.01–1.89)], NDM [1.83 (1.40–2.41)], and KDM [2.83 (2.26–3.55)] groups, in the age- and sex-adjusted model. Furthermore, in the full-adjusted model, only NDM and KDM status remained to be associated with the presence of CHD by ORs of 1.40 (1.06–1.86) for NDM and 1.91 (1.51–2.43) for KDM.

Conclusion

The high prevalence of CHD, especially among diabetic populations, necessitates the urgent implementation of behavioral interventions in the Tehranian population, according to evidence-based guidelines for the clinical management of diabetic patients.

The association of dietary macronutrients with anthropometric changes, using iso-energetic substitution models: Tehran lipid and glucose study

Background

The consequences of optimal dietary macronutrient compositions especially quality of proteins on weight gain still remain controversial. The aim of the current study was to evaluate the iso-energetic substitution of dietary macronutrients in relation to anthropometric changes.

Methods

This prospective study was conducted on 2999 men and 4001 women aged 20–70 years who were followed for 3.6 years. A valid and reliable 168-item semi-quantitative food frequency questionnaire was used to assess usual dietary intakes. Weight (kg) and waist circumference (WC) (cm) changes were calculated by subtracting the weight and WC at baseline from their measurements at follow up. Participants were divided into two groups; those with no change or decrease in weight or WC and those with increase in weight or WC. Dietary macronutrients (percentage of energy) divided by 5 to calculate one unit.

Results

A one unit higher proportion of carbohydrates at the expense of all types of fatty acids was associated with weight loss in men (P < 0.05). A one unit higher proportion of plant proteins at the expense of animal protein (β = − 0.84), non-starch carbohydrates (β = − 0.86), saturated fat (β = − 0.76), mono-unsaturated fat (β = − 0.76) and poly-unsaturated fat (β = − 0.86) was associated with weight loss (P < 0.05). A one unit higher proportion of plant proteins at the expense of animal proteins (OR: 0.49), non-starch carbohydrates (OR: 0.49), saturated fat (OR: 0.49), mono-unsaturated fat (OR: 0.49), and poly-unsaturated fat (OR: 0.48) was associated with a lower risk of increase in WC (P < 0.05).

Conclusions

A higher proportion of dietary plant protein in replacement of simple carbohydrates, fats and animal proteins was associated with a lower increase in weight or WC.

Elevated serum levels of aminotransferases in relation to unhealthy foods intake: Tehran lipid and glucose study

BACKGROUND

Abnormal levels of liver enzymes, particularly aminotransferases, are prognostic features of non-alcoholic fatty liver disease (NAFLD). Considering the important role of dietary intakes in development of NAFLD, we aimed to determine possible association of unhealthy foods (fast foods, soft drinks, sweet and salty snacks) consumption with elevated levels of aminotransferases.

METHODS

This cross-sectional study was conducted within the framework of sixth phase of the Tehran Lipid and Glucose Study (2014-2017), on 187 adult men and 249 adult women (19-70 y). Usual intakes of unhealthy foods (kcal/week) were measured using a validated semi-quantitative 147-items food frequency questionnaire. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) were measured. Multivariable logistic regression models were used to estimate the odds of elevated aminotransferases in each tertile of energy-dense unhealthy foods.

RESULTS

Mean age of participants was 44.44 ± 15.09 years, 43% of participants were men. Higher consumption of fast foods (> 11.39% kcal/week) was associated with elevated ALT to AST ratio (OR: 3.27; 95% CI: 1.90-5.63) and elevated ALT (OR: 2.74; 95% CI: 1.57-4.76). Also, each 1 SD increased energy intakes from fast foods was related to increased chance of having elevated ALT and ALT to AST ratio by 35% (OR: 1.35; 95% CI: 1.08-1.68, OR: 1.35; 95% CI: 1.10-1.66, respectively). There was no significant association between consumption of soft drinks, sweet or salty snacks and elevated aminotransferases.

CONCLUSIONS

Higher intakes of energy from fast foods seems to be associated with an elevated serum levels of ALT and ALT to AST ratio, as indicators of development of NAFLD.

The influence of the fatty acid amide hydrolase 385C>A single nucleotide polymorphisms on obesity susceptibility

The chronic over-activation of the endogenously produced cannabinoids in obesity has been demonstrated in several studies. A common 385C>A single nucleotide polymorphism of the fatty acid amide hydrolase, one the most important inactivating enzymes of endogenous cannabinoids, has been shown to be associated with obese phenotype. This study was designed to investigate the FAAH gene polymorphisms and to compare the obesity indices between different genotypes in Iranian overweight/obese women. A total of 180 healthy overweight/obese subjects (BMI = 25 to 40 kg/m²) and 86 normal weight individuals (BMI = 18.5 to 24.9 kg/m²) were genotyped for 385 C/A polymorphism of FAAH using amplification refractory mutation system (ARMS)-PCR. Anthropometric indices including BMI, waist circumference, neck circumference, waist to height ratio, fat mass were evaluated. A written informed consent form was given by the participants. The genotype and allele frequencies were significantly different between the overweight/obese and control groups (P = 0.04). Significant differences were observed between the CC genotype and the AA+CA genotype regarding the anthropometric indices (P < 0.05). Compared to CC group, a higher BMI, WC, WHtR, NC and fat mass was identified in allele A carriers group. After adjusting for age, marital and physical activity status, it was revealed that having the CA/AA genotype increased the probability of obesity risk almost two times (P < 0.05, 95% CI 1.19-3.67). Our findings showed that the frequency of A allele was greater in overweight/obese individuals. Also, a mutation in FAAH gene was associated with higher anthropometric indices and the CA/AA genotype increased significantly the possibility of being obese in Iranian women.

Contributions and Implications of the Tehran Lipid and Glucose Study

Tehran Lipid and Glucose Study (TLGS), an epidemiological study of non-communicable disease with 20 years follow up in a developing country in nutrition transition is a unique study in 15000 family based individuals, 3 - 75 years of age in a part of large city of Tehran. The success rate of recruitment for 20 years, intervention for lifestyle change, and thyroid, reproduction and cardiometabolic genetic studies derived from TLGS have paved suitable path towards precision medicine. In this review, baseline findings and changes of risk factors for the development of NCD including body weight, nutrition, physical activity, blood pressure, tobacco smoking, serum glucose and serum lipids as well as metabolic syndrome, chronic kidney disease, quality of life and biochemical findings in TLGS cohort have been summarized. The results of community based intervention for lifestyle change caused decreases in the prevalence of metabolic syndrome and the incidence of diabetes. It is concluded that TLGS has served as a model for other cohort studies in Iran and the region; it has helped to mobilize scientists in developing countries; it has established locally needed definitions of NCD variables; has served as a model for cohort studies in developing countries in nutrition transition with all socioeconomic constraints and has helped manpower education and development of local CVD risk scores for implementation of NCD management.