Utility of waist circumference-to-height ratio as a screening tool for generalized and central obesity among Iranian children and adolescents: The CASPIAN-V study

Association Between Obesity and Blood Pressure Among Iranian Children and Adolescents: A Sub-analysis from the SHED LIGHT Study

Childhood obesity has become a major non-communicable disease worldwide. It is associated with an increased risk of cardiometabolic factors, including diabetes and hypertension (HTN). The purpose of this study was to evaluate the association between obesity and HTN among Iranian children and adolescents. Cross-sectional data from the SHED LIGHT study performed in Tehran urban area were used in this report. The anthropometric values and blood pressure were analyzed. The obesity status was identified based on body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR). The blood pressure status was defined using percentiles for height, age, and sex. A total of 14,641 children with a mean age of 12.28 ± 3.1 years (6-18) were assessed, and 52.8% of them were boys. The prevalence of HTN was higher among obese compared to healthy weight subjects (p < 0.001). HTN had the strongest association with the central obesity by WC (odds ratio [OR] 4.098, 95% confidence interval [CI] 3.549-4.732), generalized obesity by BMI (OR 3.000, 95% CI 2.749-3.274), and central obesity by WHtR (OR 2.683, 95% CI 2.451-2.936). Moreover, parental university education, having studied in private schools, and the smaller number of household children increased the risk of obesity. The rate of HTN was high among children and adolescents with generalized and central obesities. HTN, elevated blood pressure, boy gender, and socioeconomic status were associated with obesity, emphasizing on the importance of screening and implementing lifestyle changes to decrease future risk of cardiovascular diseases.

Reference percentiles for tri-ponderal mass index and its association with general and abdominal obesity among Iranian children and adolescents: A report from the SHED LIGHT study

BACKGROUND

The body mass index (BMI) has some limitations in identifying obesity, particularly among children and adolescents.

OBJECTIVES

We sought to determine the reference percentiles of tri-ponderal mass index (TMI) for Iranian population, and its relation to BMI, waist circumference (WC), and waist circumference-to-height ratio (WHtR).

METHODS

Baseline characteristics for 14 641 children and adolescents were applied. The area under the characteristics (AUC) curve and optimal cut-off points for TMI were used to define the accuracy of TMI for discriminating general and central obesity compared to other anthropometric measurements.

RESULTS

TMI levels remained stable from 6 to 18 years with a small range of difference. The highest AUCs for discriminating obesity according to BMI and WHtR ≥0.5 from non-obese subjects were related to TMI (0.980) and TMI (0.912), respectively, and these findings were similar for both sexes. Moreover, the AUC for TMI to discriminate central obesity by WHtR was higher than that for BMI (0.912 vs. 0.833, p < .001), and this difference was similar among sex and age groups. The optimal value of TMI for discriminating general obesity, obesity by WC, and obesity by WHtR were 15.2 (sensitivity 96.2 and specificity 89.8), 15 (sensitivity 86.9 and specificity 79.9), and 13.9 (sensitivity 85.1 and specificity 81.5), respectively.

CONCLUSIONS

TMI discriminated central obesity by WHtR more accurately than obesity by BMI among Iranian children and adolescents irrespective of sex. Besides it remained relatively constant across age- and sex-specific groups providing a single optimal cut-off point for screening obesity during childhood and adolescence.

Optimal cut-off value of waist circumference-to-height ratio to predict central obesity in children and adolescents: A systematic review and meta-analysis of diagnostic studies

Introduction

Waist circumference-to-height ratio (WHtR) is a simple anthropometric index with good screening power and fast interpretation for early detection of childhood abdominal obesity. This systematic review and meta-analysis aims to determine the best cut-off value of WHtR to use in clinical setting.

Methods

Comprehensive searches were conducted in PubMed, Scopus, and Web of Science by the end of March 2021. Observational studies investigated the best WHtR cut-off to detect abdominal obesity in children and adolescents were included. Thirteen articles (n = 180,119) were included in this systematic review and eight documents were included in the meta-analysis.

Results

The overall optimal cut-off was 0.49 with pooled sensitivity, specificity and diagnostic odds ratio (DOR) of 0.93 (95% confidence interval (CI): 0.93-0.96), 0.88 (95% CI: 0.85-0.91) and 102.6 (95% CI: 50.7-207.5), respectively. The optimal WHtR cut-off to predict abdominal obesity in girls and boys were both 0.49.

Discussion

The current study shows that we could use this cut-off as a simple index for predicting abdominal obesity in children and adolescents without the need for any charts in practice.

Waist-to-height ratio is a simple and practical alternative to waist circumference to diagnose metabolic syndrome in type 2 diabetes

BACKGROUND

As an indicator of abdominal obesity, waist circumference (WC) varied with race and gender in diagnosing metabolic syndrome (MetS). Therefore, it is clinically important to find an alternative indicator of abdominal obesity independent of these factors to diagnose MetS. Our aims were to evaluate the association between waist-to-height ratio (WHtR) and MetS and further determine whether WHtR could be used as a simple and practical alternative to WC to diagnose MetS in patients with type 2 diabetes mellitus (T2DM).

METHODS

This cross-sectional, real-world study recruited 8488 hospitalized T2DM patients including 3719 women (43.8%) aged from 18 to 94 years and 4769 men (56.2%) aged from 18 to 91 years. A WHtR cut-off of 0.52 was used to diagnose MetS in both men and women T2DM patients based on our previous study. The association of WHtR with MetS in T2DM patients was analyzed by binary logistic regression. The consistency of two diagnostic criteria for MetS according to WC and WHtR was determined by Kappa test.

RESULTS

The prevalence of MetS according to WHtR was 79.4% in women and 68.6% in men T2DM patients, which was very close to the prevalence of MetS according to WC in both women (82.6%) and men (68.3%). The prevalence of MetS diagnosed by WC in both men and women with WHtR ≥ 0.52 was significantly higher than in those with WHtR < 0.52 after adjustment for age and duration of diabetes (89.2 vs. 38.7% for men; 92.8 vs. 57.4% for women; respectively, all p < 0.001). Binary logistic regression analysis displayed that after adjusting for confounding factors, WHtR was significantly associated with the presence of MetS in both men and women (men: OR = 4.821, 95% CI: 3.949-5.885; women: OR = 3.096, 95% CI: 2.484-3.860; respectively, all p < 0.001). Kappa test revealed that there was an excellent consistency between the diagnosis of MetS based on WC and on WHtR in T2DM patients (men: kappa value = 0.929, 95% CI: 0.918-0.940; women: kappa value = 0.874, 95% CI: 0.854-0.894; total: kappa value = 0.911, 95% CI: 0.901-0.921; respectively, all p < 0.001).

CONCLUSION

WHtR is independently associated with the presence of MetS and can be used as a simple and practical alternative to WC to diagnose MetS regardless of gender in T2DM patients.

Determinants of Waist-to-Height Ratio and Its Relation to Hypertension among School Children in India: A Multicenter Study

OBJECTIVE

To study the factors associated with waist-to-height ratio (WHtR) among school children aged 5-15 y and its association with hypertension.

METHODS

In this cross-sectional study, data on background characteristics, socioeconomic status (SES), anthropometric parameters, and blood pressure were obtained from school children from three states of India. WHtR ≥ 0.5 was defined as obesity and hypertensives were defined based on Fourth Report criteria. Descriptive statistics were applied and multiple linear regression was done to identify factors associated with WHtR. A receiver operating characteristics (ROC) analysis was used to evaluate the predictive ability of WHtR to predict hypertension RESULTS: The mean WHtR among the 12,068 students was 0.40 (± 0.05) and it showed a U-shaped distribution with age with trough at 10 y of age for both genders. Mean WHtR was higher among residents of Manipur, among boys and hypertensives. WHtR was positively associated with weight > 30 kg, male gender, schools with high SES, Manipur and Goa region, and negatively associated with age > 10 y. The area under the ROC curve of WHtR for diagnosis of hypertension was low 0.544 (95% CI 0.532, 0.556).

CONCLUSION

There is a nonlinear relation between age, gender, and WHtR, which varies by geographical region and HT. This would need to be kept in mind while using it to identify obesity in children, though its discriminant value for hypertension is low.

Triglyceride: A mediator of the association between waist-to-height ratio and non-alcoholic fatty liver disease: A second analysis of a population-based study

OBJECTIVE

Increasing evidence suggests that an increased waist-to-height ratio (WHtR) may increase the risk of non-alcoholic fatty liver disease (NAFLD). Whether this association is due to WHtR itself or mediated by WHtR-associated increases in triglyceride (TG) is uncertain. On that account, our research aims to disentangle these relationships.

METHODS

In this cross-sectional study, 14251 participants who participated in the medical examination program were consecutively and non-selectively collected in Murakami Memorial Hospital in Japan from 2004 to 2015. The independent and dependent variables were WHtR and NAFLD, respectively. Triglyceride was the mediating factor. The correlation between WHtR, TG, and NAFLD risk factors was examined using spearman correlation analysis. The association between WHtR or TG and NAFLD was examined using multiple logistic regression. In order to determine whether TG mediated the association between WHtR and NAFLD, a mediation analysis was performed.

RESULTS

The mean age of the included individuals was 43.53 ± 8.89 years old, and 7411 (52.00%) were male. The mean WHtR and TG were 0.46 ± 0.05, 0.89 ± 0.63, respectively. The prevalence rate of NAFLD was 2507 (17.59%). Individuals with NAFLD had significantly higher levels of WHtR and TG than those without NAFLD (P&lt;0.05). After adjusting covariates, the multivariate linear regression analysis showed that WHtR was positively associated with TG. That was, for every 0.1 increase in WHtR, TG increased by 0.226mmol/L (β=0.226, 95%CI: 0.206, 0.247). Multiple logistic regression analysis indicated that WHtR (OR=8.743, 95%CI: 7.528, 10.153) and TG (OR=1.897, 95%CI: 1.732, 2.078) were positively associated with NAFLD. The mediation analysis showed that WHtR had a direct, significant effect on NAFLD (β=0.139, 95%CI: 0.126, 0.148), and TG partially mediated the indirect effect of WHtR on NAFLD (β=0.016, 95% CI: 0.013-0.019). TG contributed to 10.41% of WHtR-related NAFLD development.

CONCLUSION

Findings suggest a mediation link between WHtR and TG and the risk of NAFLD. The significance of TG as a mediator deserves recognition and consideration.

Association of short stature and obesity with cardio-metabolic risk factors in Iranian children and adolescents: the CASPIAN-V study

Purpose

The object of the present study was to examine the relationship of short stature and obesity with cardio-metabolic risk factors in children and adolescents from Iran.

Methods

Present nationwide cross-sectional study was conducted as a part of the fifth survey of CASPIAN study on 7 to 18 years old children and adolescents from 30 provinces of Iran in 2015. Short stature and excess weight were defined as age and sex-specific height lower than 5^th percentile and BMI higher than 85^th percentile respectively. The multivariate logistic regression model was applied to assess the aim of the study.

Results

A total of 3844 children and adolescents (52.4%: boys, 72.2%: urban areas) with an average age of 12.45 ± 3.04 years were enrolled in this study. The prevalence of short stature, excess weight and combined-short stature and excess weight was estimated as 15.8%, 17.6% and 2.2%. Odds of abdominal obesity in children with only short stature (OR: 2.11, 95%CI: 1.59-2.80), only excess weight (OR: 17.38, 95%CI: 13.89-21.75) and combined-short stature and excess weight (OR: 22.83, 95%CI: 13.93-37.39) were higher than children with normal-height and weight. Moreover, odds of high BP and metabolic syndrome were further in the students with combined excess weight and short stature compared to the normal-height and weight group.

Conclusion

We found that abdominal obesity, hypertension, and metabolic syndrome in short stature and obese children and adolescents were greater than those with normal-height and weight. Further prospective evaluations are required to clarify the association between short stature and cardio-metabolic risk factors.

Performance of waist-to-height ratio as a screening tool for identifying cardiometabolic risk in children: a meta-analysis

OBJECTIVE

To provide the latest evidence of performance and robustness of waist-to-height ratio (WHtR) in discriminating clusters of cardiometabolic risk factors (CMRs) and promote WHtR in routine primary health care practice in children, a meta-analysis was used.

METHODS

Searches was performed in eight databases from inception to July 03, 2020. Inclusion criteria were: (1) observational study, (2) children and adolescents, (3) provided WHtR measurements, (4) had CMRs as outcomes, and (5) diagnostic studies. Exclusion criteria were: (1) non-original articles, (2) unable to extract 2 × 2 contingency tables, (3) not in English or Chinese language, (4) populations comprising clinical patients, or (5) duplicate articles. WHtR cutoff points, 2 × 2 contingency tables were extracted from published reports. Outcomes included: CMR clusters of at least three CMRs (CMR₃), two (CMR₂), one (CMR₁), and CMR components. Bivariate mixed-effects models were performed to estimate the summarised area under the curves (AUSROC) with 95% CIs and related indexes. We conducted subgroup analyses by sex and East Asian ethnicity.

RESULTS

Fifty-three observational studies were included. The AUSROC reached 0.91 (95% CI: 0.88-0.93), 0.85 (95% CI: 0.81, 0.88) and 0.75 (95% CI: 0.71, 0.79) for CMR₃, CMR₂, and CMR₁, respectively. The pooled sensitivity and specificity for CMR₃ reached 0.84 and exceeded 0.75 for CMR₂. For CMR₁, the sensitivity achieved 0.55 with 0.84 for specificity. We had similar findings for our subgroup and sensitivity analyses.

CONCLUSIONS

WHtR shows good and robust performance in identifying CMRs clustering across racial populations, suggesting its promising utility in public health practice globally.

Association of a body shape index and hip index with cardiometabolic risk factors in children and adolescents: the CASPIAN-V study

OBJECTIVE

This study designed to discover the link between a body shape index (ABSI) and hip index (HI) with cardiometabolic risk factors (CMRFs) in Iranian children and adolescents.

SUBJECTS AND METHODS

In a nationwide cross-sectional survey, 4200 students who were 7-18 years old were chosen via a multistage cluster sampling method in 30 provinces of Iran in 2015. Metabolic syndrome (MetS) was defined in line with the Adult Treatment Panel III criteria. ABSI and HI were defined as waist circumference (m)/ [body mass index 2/3 * height (m)1/2] and hip circumference (cm) *(height/ 166 cm)0.310 *(weight / 73 kg)-0.482 respectively. Association between ABSI and HI with CMRFs as categorical and continuous variables were evaluated using multivariable logistic and linear regression analysis respectively.

RESULTS

Totally, information of 14,002 students and findings of blood samples of 3483 of them were involved in the current study. In the multivariable logistic regression, an association of HI with high triglyceride (TG) (OR: 0.99, 95 % CI: 0.98-0.99) and ABSI with MetS (OR: 11.41, 2.61-49.88) was statistically significant (P < 0.05). Also, both indices were significantly associated with overweight, generalized, and abdominal obesity. In the multivariable linear regression analysis, increasing HI (per one unit) was associated with body mass index z-score (z-BMI) (β: -0.01), waist circumference (WC) (β: 0.15), TG (β: -0.16), and systolic blood pressure (SBP) (β: -0.02). Moreover, in the multivariable linear models, ABSI was significantly associated with z-BMI, WC, SBP, and diastolic blood pressure (P < 0.001).

CONCLUSIONS

ABSI and HI as novel body shape indices were significantly associated with some CMRFs. Therefore, these indices can be used as some useful anthropometric risk indices for predicting MetS.

A comparison between body mass index and waist circumference for identifying continuous metabolic syndrome risk score components in Iranian school-aged children using a structural equation modeling approach: the CASPIAN-V study

PURPOSE

The purpose of this study was to investigate the association of anthropometric indices with continuous metabolic syndrome (cMetS) risk score components in a large population-based sample of children and adolescents.

METHODS

This multi-centric study was performed on 3843 students aged 7-18 years who were selected by multistage, stratified cluster sampling method from 30 provinces of Iran. Demographic, anthropometric and biochemical factors were obtained and standardized residuals (z-scores) were calculated for MetS components. A structural equation modeling approach was applied to evaluate the relationships among the study variables and to implement the subsequent structural modeling.

RESULTS

The mean age of the participants (52.3% boys) was 12.4 ± 3.05 years. Standardized scores of body mass index (ZBMI) and waist circumference (ZWC) had a direct effect on standardized scores of mean arterial pressure (ZMAP) (0.23 and 0.24 in boys and 0.22 and 0.23 in girls, respectively) and triglyceride (ZTG) (0.07 and 0.04 in boys and 0.02 and 0.06 in girls, respectively), but the effect of ZWC was stronger than ZBMI on these variables. Age, socioeconomic status and sedentary behaviors showed a positive direct effect on ZWC (0.01, 0.05 and 0.07 in boys and 0.05, 0.08 and 0.002 in girls, respectively). These variables induced indirect effects on cMets risk score components through ZWC.

CONCLUSION

The magnitude of association between WC and continuous metabolic syndrome risk score components was higher compared to BMI in school-aged children, emphasizing on paying more attention to central obesity in childhood.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study.

Waist-to-height ratio and non-alcoholic fatty liver disease in adults

Background

The waist-to-height ratio (WHtR) has been recognised as a powerful indicator to evaluate non-alcoholic fatty liver disease (NAFLD) in recent years, but few related studies are available. Thus, clarifying the association between the WHtR and NAFLD may be beneficial to the prevention and treatment of NAFLD.

Methods

The cross-sectional study population was from a large-scale health examination programme called ‘human dock’ in Japan. In this study, 14,125 participants in this health examination programme were included. To understand the association between the WHtR and NAFLD more intuitively, we grouped the WHtR values into quintiles and used a multivariable logistic regression model to assess WHtR and its quintile with NAFLD risk. Moreover, we used the generalised additive model to model the association between WHtR and NAFLD to explore their non-linear relationship.

Results

The prevalence of NAFLD among participants in this study was 17.59%, with an average age of 43.53 ± 8.89 years. After adjusting for all non-collinear covariables, we observed a 66% increase in the NAFLD risk per SD increase in WHtR. Furthermore, in the quintile groups of WHtR, the participants in quintile 2, quintile 3, quintile 4, and quintile 5 had 3.62-fold, 5.98-fold, 9.55-fold, and 11.08-fold increased risks of NAFLD, respectively, compared with those in quintile 1 (P_trend < 0.0001). Non-linear relationship analysis revealed threshold and saturation effects between WHtR and NAFLD in which a WHtR of approximately 0.4 might be the threshold effect of NAFLD risk, 0.6 might be the saturation effect of NAFLD risk. Additionally, subgroup analysis showed that the interaction between WHtR and BMI was significant.

Conclusions

Our results suggest that in adults, the WHtR is associated with NAFLD, and the association is not purely linear but non-linear, with significant threshold and saturation effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01824-3.

Decomposition of socioeconomic inequality in growth disorders to its determinants in pediatric population: the CASPIAN IV study

Purpose

The current study aims to evaluate socioeconomic inequality in growth disorders and its determinants in Iranian children and adolescents.

Methods

In this nationwide cross-sectional survey, 14,880 students aged 6-18 years were selected through multistage cluster sampling method from urban and rural areas of 30 provinces of Iran in 2011. Socioeconomic status (SES) was calculated using principle component analysis. Socioeconomic inequality in growth disorders (including; underweight, excess weight, overweight, general obesity, abdominal obesity, and short stature) was assessed using concentration index (C) and slope index of inequality (SII). The Oaxaca Blinder decomposition method was used to determine determinants of this inequality.

Results

Totally, 13,486 students participated in this study (participation rate: 90.6%), comprising 50.8% boys and 75.6% urban inhabitants. Their mean age was 12.47 ± 3.36 years with no significant gender difference. The prevalence of excess weight, overweight, and general and abdominal obesity increased linearly as SES increased, and the prevalence of underweight and short stature decreased linearly as SES increased. The C index for underweight and short stature was negative, which suggests that inequality was in favor of high SES groups, and regarding overweight, excess weight, general and abdominal obesity, the index was positive, indicating that inequality was in favor of in low SES groups.

Conclusion

Our findings show a considerable inequality in prevalence of growth disorders in Iranian children and adolescents. These findings provide practical information for health policies and programs.

Novel and traditional anthropometric indices for identifying metabolic syndrome in non-overweight/obese adults

Background

Metabolic syndrome (MetS) in non-overweight/obese people is insidiously associated with cardiovascular disease. Novel anthropometric indices can reflect central obesity better than the traditional anthropometric indices. Therefore, we hypothesize that these newly developed anthropometric indices can better identify MetS in non-overweight/obese people than conventional indices.

Methods

Cross-sectional data of sociodemographic, biochemical and anthropometric indices were collected from 2916 non-overweight/obese Chinese people. A body shape index (ABSI), body roundness index (BRI), waist-to-height ratio (WHtR), weight-adjusted-waist index (WWI) and abdominal volume index (AVI) were calculated. Partial correlation analysis was used to clarify the correlation between anthropometric indices and MetS variables. Binary logistic regression analysis was applied to assess the association between anthropometric indices and MetS and its components. Receiver-operating characteristic curve was used to identify the diagnostic ability of anthropometric indices for MetS and its components. The area under curve (AUC) difference between WHtR and each new anthropometric index was compared in pairs.

Results

After adjusting for covariates, AVI had the optimal ability of identifying MetS (AUC: 0.743 for male, 0.819 for female) and the strongest correlation with high-density lipoprotein cholesterol (HDL-C) (coe: − 0.227 for male, − 0.207 for female) and the highest odds rations (OR) with low HDL-C group (male: OR = 1.37, female: OR = 1.55). The WHtR was comparable to BRI in assessing MetS (AUC: 0.739 for male, 0.817 for female). WHtR or BRI could also well identify hypertension (AUC: 0.602 for male, 0.688 for female) and dysglycemia (AUC: 0.669 for male, 0.713 for female) and female’s high triglyceride level (AUC 0.712). The recognition ability of the two was equivalent. The ability of ABSI and WWI to identify MetS was weak.

Conclusions

AVI is the optimal anthropometric indices to identify MetS in non-overweight/obese Chinese adults. BRI and WHtR can also be considered as discriminators, while ABSI and WWI are weak discriminators. WHtR is easy to measure. So, it is recommended as an early preliminary screening method for the MetS in non-overweight/obese people.

The Effects of Obesity-Related Anthropometric Factors on Cardiovascular Risks of Homeless Adults in Taiwan

Homelessness is a pre-existing phenomenon in society and an important public health issue that national policy strives to solve. Cardiovascular disease (CVD) is an important health problem of the homeless. This cross-sectional study explored the effects of four obesity-related anthropometric factors-body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR)-on cardiovascular disease risks (expressed by three CVD markers: hypertension, hyperglycemia, and hyperlipidemia) among homeless adults in Taipei and compared the relevant results with ordinary adults in Taiwan. The research team sampled homeless adults over the age of 20 in Taipei City in 2018 and collected 297 participants. Through anthropometric measurements, blood pressure measurements, and blood tests, we calculated the obesity-related indicators of the participants and found those at risks of cardiovascular disease. The results showed that the prevalence of hypertension, hyperglycemia, and hyperlipidemia in homeless adults was significantly higher than that of ordinary adults in Taiwan. Among the four obesity-related indicators, WHtR showed the strongest association with the prevalence of hypertension and hyperlipidemia, followed by WHR, both of which showed stronger association than traditional WC and BMI indicators. It can be inferred that abdominal obesity characterized by WHtR is a key risk factor for hypertension and hyperlipidemia in homeless adults in Taiwan. We hope that the results will provide medical clinical references and effectively warn of cardiovascular disease risks for the homeless in Taiwan.

Longitudinal association between body mass index and physical activity among adolescents with different parental risk: a parallel latent growth curve modeling approach

Background

Data available on the association between physical activity (PA) and body mass index (BMI) in different periods of life is controversial. Using a parallel latent growth curve modeling (LGCM) approach, the current study aimed to investigate the influence of daily PA on adolescents’ BMI over a 12 year follow-up, taking into account their parental risk.

Method

Participants comprised 1323 adolescents (53.5% girls), aged 12–18 years who had participated in the baseline phase of Tehran Lipid and Glucose Study (TLGS) (2001–2003), and were followed for an average period of 12 years. Physical activity, including leisure time and occupational activities, was assessed using the reliable and validated Iranian version of the Modifiable Activity Questionnaire (MAQ). Weight and height were objectively measured in order to calculateBMI.Atwo-step cluster analysis was conducted to classify parents into two high- and low-risk clusters. Parallel LGCM was fitted to estimate cross-sectional, prospective and parallel associations, which assessed the longitudinal association between simultaneous changes in PA and BMI during the study period. Analyses were stratified by gender and parental clusters.

Results

A rising trend of BMI per 3 years was observed in boys 1.39 kg.m²(95% CI; 1.32, 1.48) and girls 0.9 kg.m²(95% CI; 0.82, 0.98), as well as in the low risk 1.11 kg.m²(95% CI; 1.03, 1.18) and high-risk 1.12 kg.m²(95% CI; 1.03, 1.22) clusters. Moreover, a positive prospective association between PA at baseline and BMI change over the 12 year follow-up, was observed in adolescents in the low-risk parental cluster 0.27(95% CI; 0.14, 0.41) indicating that higher levels of PA at baseline may lead to greater BMI in adolescents over time. However, examining longitudinal parallel association between simultaneous changes of PA and BMI per 3 years revealed adverse associations for adolescents in the low-risk parental cluster − 0.07 (95% CI; − 0.13, − 0.01) and in boys − 0.06 (95% CI; − 0.11, − 0.01).

Conclusion

Despite a positive prospective association between BMI and PA at baseline, there was a weak inverse parallel association between these variables over time, particularly in boys and adolescents with low parental risk. These findings imply the potential role of other influential factors indetermining adolescents’ weight status which need to be considered in the future plannings.

Novel Insights into the Pathogenesis and Management of the Metabolic Syndrome

The metabolic syndrome, by definition, is not a disease but is a clustering of individual metabolic risk factors including abdominal obesity, hyperglycemia, hypertriglyceridemia, hypertension, and low high-density lipoprotein cholesterol levels. These risk factors could dramatically increase the prevalence of type 2 diabetes and cardiovascular disease. The reported prevalence of the metabolic syndrome varies, greatly depending on the definition used, gender, age, socioeconomic status, and the ethnic background of study cohorts. Clinical and epidemiological studies have clearly demonstrated that the metabolic syndrome starts with central obesity. Because the prevalence of obesity has doubly increased worldwide over the past 30 years, the prevalence of the metabolic syndrome has markedly boosted in parallel. Therefore, obesity has been recognized as the leading cause for the metabolic syndrome since it is strongly associated with all metabolic risk factors. High prevalence of the metabolic syndrome is not unique to the USA and Europe and it is also increasing in most Asian countries. Insulin resistance has elucidated most, if not all, of the pathophysiology of the metabolic syndrome because it contributes to hyperglycemia. Furthermore, a major contributor to the development of insulin resistance is an overabundance of circulating fatty acids. Plasma fatty acids are derived mainly from the triglycerides stored in adipose tissues, which are released through the action of the cyclic AMP-dependent enzyme, hormone sensitive lipase. This review summarizes the latest concepts in the definition, pathogenesis, pathophysiology, and diagnosis of the metabolic syndrome, as well as its preventive measures and therapeutic strategies in children and adolescents.

Animal Protein Intake Is Associated with General Adiposity in Adolescents: The Teen Food and Development Study

Protein plays a crucial role in the growth and development of adolescents. However, being a secondary energy source, protein's role in obesity has been sidelined. We examined whether intake of protein (total, animal, plant), branched-chain (BCAAs), and sulfur-containing (SCAAs) amino acids are associated with general body and central obesity and body composition in a cross-sectional study among healthy adolescents. Students aged 12-18 years old (n = 601) in schools near two major Adventist universities in California and Michigan provided dietary data via a validated web-based food frequency questionnaire (FFQ) and anthropometric data during school visits. Intakes of total, animal, and plant proteins, and BCAAs and SCAAs were derived from FFQ data. We defined general body obesity with body-mass-index-for-age (BMIz) z-scores and central obesity with waist-to-height ratios (WHtR). After full adjustment for covariates, multiple regression analyses showed significant positive associations between intakes of total protein (β = 0.101, 95% CI: 0.041, 0.161), animal protein (β = 0.118, 95% CI: 0.057, 0.178), BCAAs (β = 0.056, 95% CI: 0.025, 0.087), and SCAAs (β = 0.025, 95% CI: 0.012, 0.038) with general body adiposity. Animal protein (β = 0.017, 95% CI: 0.001, 0.033) and SCAAs (β = 0.004, 95% CI: 0.000, 0.008) were also associated with central obesity. Total and animal protein and BCAA and SCAA were also significantly associated with fat mass. Our findings suggest that high protein intake may pose a possible detriment to adolescent health. Longitudinal and safety evaluation studies are recommended.

Association of Anthropometric Indices With Metabolic Phenotypes of Obesity in Children and Adolescents: The CASPIAN-V Study

Background: Obesity, particularly in the upper part of the body, is a major health problem. Measuring the neck circumference (NC) and wrist circumference (WrC) is a relatively new method of differentiating between normal and abnormal fat distributions. This study aimed to evaluate the association of NC, hip circumference (HC), and WrC with different phenotypes of obesity and their metabolic status. Methods: In this multi-centric cross-sectional study, 4,200 students aged 7-18 years were selected from 30 provinces in Iran in 2014 by using a multistage cluster random sampling method. Metabolic syndrome (MetS) was defined based on the ATP III criteria modified for the pediatric age group. The subjects were classified into four groups according to their weight and metabolic status: metabolically healthy obese (MHO), metabolically non-healthy non-obese (MNHNO), metabolically non-healthy obese (MNHO), and metabolically healthy non-obese (MHNO). Results: Significant but different associations of NC, HC, and WrC with obesity phenotypes were documented in the entire population. Significant but different associations of NC, HC, and WrC with metabolic phenotypes were also found in the entire population. In the multinomial logistic regression, the association of the different obesity phenotypes with the study anthropometric indices increased significantly with increasing NC, WrC, and HC. Also, per one unit increment in NC, HC, and WrC, the odds of MHO, MNHNO, and MNHO increased compared to that of the MHNO phenotype. Conclusion: In children and adolescents, HC, NC, and WrC are significantly associated with obesity phenotypes and their metabolic status, and these metrics are suggested to be innovative, low-cost, and alternative tools for assessing them in different age and sex pediatric age groups.