BMI or BIA: Is Body Mass Index or Body Fat Mass a Better Predictor of Cardiovascular Risk in Overweight or Obese Children and Adolescents? A German/Austrian/Swiss Multicenter APV Analysis of 3,327 Children and Adolescents

BMI Z-Score (SDS) versus Calculated Body Fat Percentage: Association with Cardiometabolic Risk Factors in Obese Children and Adolescents

INTRODUCTION

BMI or BMI-standardized deviation score (SDS) in children and adolescents is still the standard for weight classification. [BMJ. 2019;366:4293] developed a formula to calculate body fat percentage (%BF) based on age, sex, height, weight, and ethnicity. Using data from the German/Austrian APV registry, we investigated whether the calculated %BF is superior to BMI-SDS in predicting arterial hypertension, dyslipidaemia, and impaired glucose metabolism.

METHODS

94,586 children and adolescents were included (12.5 years, 48.3% male). Parental birth country (BC) was used to depict ethnicity (15.8% migration background); 95.67% were assigned to the ethnicity "white." %BF was calculated based on the Hudda formula. The relationship between BMI-SDS or %BF quartiles and outcome variables was investigated by logistic regression models, adjusted for age, sex, and migration background. Vuong test was applied to analyse predictive power.

RESULTS

58.4% had arterial hypertension, 33.5% had dyslipidaemia, and 11.6% had impaired glucose metabolism. Boys were significantly more often affected, although girls had higher calculated %BF (each p < 0.05). After adjustment, both models revealed significant differences between the quartiles (all p < 0.001). The predictive power of BMI-SDS was superior to %BF for all three comorbidities (all p < 0.05).

DISCUSSION

The prediction of cardiometabolic comorbidities by calculated %BF was not superior to BMI-SDS. This formula developed in a British population may not be suitable for a central European population, which is applicable to this possibly less heterogeneous collective. Additional parameters, especially puberty status, should be taken into account. However, objective determinations such as bioimpedance analysis may possibly be superior to assess fat mass and cardiometabolic risk than calculated %BF.

The association of body composition and fat distribution with hypertension in community-dwelling older adults: the Bushehr Elderly Health (BEH) program

BACKGROUND

A significant proportion of the global burden of disability and premature mortality has caused by hypertension. It seems that the relationship between obesity and hypertension is not only associated with excessive body fat mass (FM) but also with body adipose distribution patterns. The present study investigated the association between regional fat distribution using dual-energy X-ray absorptiometry and hypertension in older adults.

METHODS

This cross-sectional study was performed using the data from Bushehr Elderly Health Program (BEH) on a total of 2419 participants aged 60 and over. Hypertension was defined as SBP of at least 140 mmHg and/or DBP of at least 90 mmHg. SBP between 120 and 139 mmHg and/or a DBP between 80 and 89 mmHg were considered prehypertension. Participants underwent body composition measurement by dual-energy x-ray absorptiometry to analyze FM, fat-free mass (FFM) in trunk and extremities composition.

RESULTS

The results showed that 460 (19.02%) of participants had prehypertension, and 1,818 (75.15% ) had hypertension. The odds of having prehypertension (OR: 1.06, 95%CI: 1.01-1.12) and hypertension (OR: 1.08, 95%CI: 1.03-1.13) increased with a rise in total body FM percentage. Moreover, people with a higher FM to FFM ratio had increased odds of being prehypertensive (OR: 9.93, 95%CI: 1.28-76.99) and hypertensive (OR: 16.15, 95%CI: 2.47-105.52). Having a higher android to gynoid FM ratio was related to increased odds of being prehypertensive and hypertensive.

CONCLUSIONS

This study showed that a higher body FM, particularly in the android region, is associated with higher odds of having hypertension in older adults.

Anthropometric Indicators of Body Composition Associated With Lipid and Glycemic Profiles in Overweight Brazilian Children and Adolescents From 2008 to 2020

Background

Anthropometric indicators have been used to predict health problems. The objective was to determine which indicators present better correlation with dyslipidemia, hyperglycemia and peripheral insulin resistance, as well as the cutoff points capable of predicting lipid and glycemic alterations in Brazilian children and adolescents.

Methods

A cross-sectional study conducted with 568 overweight individuals, aged between 5 and 18 years, living in Southeast and South Brazilian regions, submitted to anthropometric and body composition evaluation by bioimpedance, in addition to fasting laboratory tests [total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), fasting glycemia, and homeostasis model assessment–insulin resistance (HOMA-IR)]. Pearson's correlation was used to evaluate the association between anthropometric indicators and serum biomarkers. The ROC curve with Youden's J index was used to suggest anthropometric cutoff points with better ability to predict or rule out lipid and glycemic changes.

Results

Cutoff points obtained for the z-score of body mass index (BMI), waist circumference (WC), and waist circumference for height (WC/H) showed high specificity (52 to 87%) and low sensitivity (23 to 59%), indicating greater ability to exclude changes in HDL-c, TG, and HOMA-IR levels. Cutoff points suggested for BMI ranged from +1.86 to +2.20 z-score. WC cutoff points ranged from +1.29 to +1.72, and, for the WC/H index, from +1.21 to +1.25. It was suggested the use of the following cutoff points to rule out changes in HDL-c, TG, and HOMA-IR values in clinical practice: BMI < z-score +2 and WC/H < z-score +1.29. In body fat percentage (BFP) analyses, the cutoff point < of 34% may be able to rule out changes in HDL-c (specificity of 70%), while the cutoff point > 36.6% may be able to predict changes in the HOMA-IR index (sensitivity of 76%).

Conclusion

It is not yet possible to state which anthropometric parameter has the best correlation with lipid and glycemic alterations in overweight children and adolescents. We suggest considering BMI, WC, and WC/H cutoff points together to rule out changes in HDL-c, TG, and HOMA-IR, and use the BFP cutoff point to predict changes in HOMA-IR.

Gender-specific predictive ability for the risk of hypertension incidence related to baseline level or trajectories of adiposity indices: a cohort study of functional community

BACKGROUND

Early prevention of hypertension is important for global cardiovascular disease morbidity and mortality. This study aims to explore better predictors for hypertension incidence related to baseline level or trajectories of adiposity indices, as well as the gender-specific effect.

METHODS

6085 subjects from a functional community cohort in urban Beijing participated in our study. Restricted cubic splines were used to estimate nonlinear associations of body mass index (BMI) and waist-to-height ratio (WHtR) as continuous variable with risk of hypertension. Stepwise logistic regression model was performed to estimate the relative risks (RRs) of adiposity indices and metabolic status, adjusted for covariates. Nomogram models and receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive power of BMI trajectory groups and WHtR trajectory groups on hypertension incidence. Further, all analysis were performed by gender.

RESULTS

The risk of hypertension incidence was related to BMI trajectory groups (persistent overweight: RR = 1.88, 95% CI: 1.48-2.37; persistent obesity: RR = 2.79, 95% CI: 2.18-3.56; persistent the highest: RR = 4.30, 95% CI: 3.20-5.78) and WHtR trajectory groups (persistent medium: RR = 2.69, 95% CI: 2.07-3.50; persistent high: RR = 3.85, 95% CI: 2.92-5.09; increasing to higher: RR = 7.00, 95% CI: 4.96-9.89). In total population, BMI trajectories and WHtR trajectories showed similar ability to predict the risk of hypertension incidence with AUC 0.723 and 0.726, respectively. After stratified by gender, both BMI trajectories and WHtR trajectories showed higher power in female than male (BMI trajectories: 0.762 vs. 0.661; WHtR trajectories: 0.768 vs. 0.661).

CONCLUSIONS

BMI and WHtR trajectories have higher predictive power for hypertension incidence compared to baseline data. Females are more vulnerable to obesity than males.

[Effectiveness of an Obesity Treatment Program for Children and Adolescents in Routine Care]

Recent studies on the treatment of overweight and obesity in children and adolescents have generally considered single psychological or somatic parameters. The present study examined the efficacy of multimodal obesity treatment in routine care in N=278 children and adolescents (ages 2-17) over 12 months using comprehensive psychological and somatic parameters. The primary endpoint was the objectively measured change of BMI-SDS (Body Mass Index Standard Deviation Score). Secondary objectives included patient-reported health-related quality of life, general and eating disorder psychopathology, weight-related self-stigmatization as well as objectively measured parameters of lipoprotein and glucose metabolism and liver enzymes. At the end of treatment after 12 months, there was significant improvement in BMI-SDS (M=-0.10; SD=0.32) and single liver enzymes in the total sample whereas psychological and other blood parameters showed no significant improvement. Treatment responders showed greater BMI-SDS reductions (M=-0.44; SD=0.22) as well as similar results concerning blood and psychological parameters compared to the total sample. This multimodal obesity treatment in routine care mostly improved patients' BMI-SDS and single somatic parameters, but not psychological parameters. Patients' psychological stressors emphasize the need for psychotherapeutic treatment going beyond reduction of BMI-SDS. Furthermore, these results underline the importance of comprehensive evaluation of psychological and somatic parameters to improve treatment outcome.

Fat-free/lean body mass in children with insulin resistance or metabolic syndrome: a systematic review and meta-analysis

BACKGROUND

Lean / Fat Free Body Mass (LBM) is metabolically involved in active processes such as resting energy expenditure, glucose uptake, and myokine secretion. Nonetheless, its association with insulin sensitivity / resistance / glucose tolerance and metabolic syndrome remains unclear in childhood.

METHODS

The current investigation aimed to examine the differences in fat-free mass /lean body mass according to the presence of insulin sensitivity/insulin resistance/glucose tolerance/metabolic syndrome in children. A systematic search was carried out in Medline/PubMed, Embase, Scopus, Web of Science, and SciELO, covering the period from each database's respective start to 21 June 2021. Two researchers evaluated 7111 studies according to the inclusion criteria: original human studies, written in English or Spanish, evaluating fat-free mass/lean body mass in children and adolescents including both with and without insulin sensitivity/insulin resistance /glucose tolerance and metabolic syndrome and reported the differences between them in terms of fat free mass/lean body mass. The results of the studies were combined with insulin sensitivity, insulin, resistance, glucose tolerance and metabolic syndrome. The standardized mean difference (SMD) in each study was calculated and combined using the random-effects model. Heterogeneity between studies was tested using the index of heterogeneity (I2), leave-one-out sensitivity analyses were performed, and publication bias was assessed using the Egger and Begg tests.

RESULTS

Finally, 15 studies which compared groups defined according to different glucose homeostasis criteria or metabolic syndrome out of 103 eligible studies were included in this systematic review and 12 studies in the meta-analysis. Meta-analysis showed lower fat-free mass/lean body mass percentage in participants with insulin resistance/glucose tolerance/metabolic syndrome (SMD -0.47; 95% CI, - 0.62 to - 0.32) while in mass units (kg), higher values were found in the same group (SMD, 1.01; 95% CI, 0.43 to 1.60).

CONCLUSIONS

Our results identified lower values of fat-free mass/lean body mass (%) in children and adolescents with insulin resistance/glucose tolerance/metabolic syndrome and higher values of fat-free mass/lean body mass when these are expressed in kg. The evidence of the impact of lean mass on children's glucose homeostasis or metabolic syndrome is limited, so future studies research should focus on explaining the effect of fat-free mass/lean body mass on different metabolic outcomes. Moreover, it may be interesting to evaluate the quality (muscle density) or functional (muscle strength) outcomes in addition to both absolute (kg) and relative (%) values in future studies. The systematic review was prospectively registered at PROSPERO (registration number CRD42019124734; available at: http://www.crd.york.ac.uk/prospero [accessed: 05 April 2019]).

The Relationship between the Waist Circumference and Increased Carotid Intima Thickness in Obese Children

Background: This study aimed to evaluate the cardiometabolic risk factors in normotensive obese and hypertensive obese (HT-obese) children by comparison of anthropomorphic measurements, fat distribution, carotid artery intima-media thickness (CIMT), and inflammatory markers. Methods: Fifty-three obese patients 10-18 years of age with a BMI-for-age/gender >95th percentile and 20 age- and gender-matched healthy volunteers enrolled in the study. Obese patients were divided into two groups according to the presence of hypertension (HT), as follows: HT-obese subgroup (n = 30) and nonhypertensive obese (non-HT-obese) subgroup (n = 23). Results: Weight standard deviation score (SDS), BMI-SDS, waist circumference (WC) SDS, and the fat tissue z-score were significantly higher (p < 0.001 for all) in the obese patients than the control groups. Obese patients had higher 24-hour systolic blood pressure (SBP) SDS and leptin, high-sensitivity C-reactive protein, tumor necrosis factor-alpha, and interleukin-6 levels. Furthermore, CIMT and CIMT-SDS were significantly higher in them. HT-obese patients (n = 30) had significantly higher WC-SDS and lower serum leptin and adiponectin levels than those of non-HT-obese group (n = 23). Finally, an association between increased CIMT-SDS and WC-SDS (β = 0.399, p = 0.002) and 24-hour SBP-SDS (β = 0.272, p = 0.009) was shown. Conclusions: Association between increased WC and HT implies the importance of central obesity in atherosclerosis. We concluded that WC measurement could be used to define risk groups since it is related to cardiometabolic complications.

Body fat percentage, obesity, and their relation to the incidental risk of hypertension

Studies have indicated that increased body fat is associated with cardiovascular risk factors including hypertension. However, there is only limited information about the influence of body fat percentage (BF%) on incident hypertension. In a cohort of Korean genome epidemiology study (KoGES), 4864 non-hypertensive participants were divided into 5 quintile groups, and followed-up for 10 years to monitor incident hypertension. Cox proportional hazard model was used to evaluate the hazard ratio (HRs) and 95% confidence interval (CI) for hypertension (adjusted HRs [95% CI]) according to BF% quintile groups. Subgroup analysis was conducted by low or high level of BF% (cutoff: 22.5% in men and 32.5% in women) and low or high level of body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR). In adjusted model, compared with BF% quintile 1, the risk of incident hypertension significantly increased over BF% quintile 3 (BF% ≥19.9%) in men (quintile 3:1.42 [1.10-1.85], quintile 4:1.58 [1.22-2.05], quintile 5:1.82 [1.40-2.36]), and quintile 4 (BF% ≥32.5%) in women (quintile 4:1.48 [1.12-1.94], quintile 5:1.56 [1.20-2.04]). Subgroup analysis showed that individuals with high BF% were significantly associated with the increased risk of hypertension even in individuals with low BMI, WC, and WHR. The risk of hypertension increased proportionally to BF% over the specific level of BF% in Koreans. Even in non-obese individuals, increase in BF% was significantly associated with the increased risk of hypertension.

The comparison of percent body fat estimated by different anthropometrics to predict the incidence of hypertension

Percent body fat (%BF) is associated with the development of hypertension. However, the power of %BF estimated by different anthropometrics to predict incident hypertension was unknown. This study was from the China Health and Nutrition Survey (CHNS). %BF was calculated using the equations with BMI, WC, and skinfold thickness and divided into low and high %BF according to ROC. Cox regression was employed to evaluate the power of different %BFs to predict the development of hypertension. When not adjusting for covariates, %BFs defined by BMI, WC, and ST were the significant predictors of the development of hypertension (all P < 0.0001; crude HR: 2.238, 3.243, and 1.574; and HR 95% CI: 2.098-2.387, 2.905-3.619, and 1.464-1.692). When three %BFs entered into model simultaneously, the significance in %BF estimated by ST disappeared (P = 0.0765; adjusted HR: 1.124; and HR 95% CI: 0.988-1.280). For males, %BFs by BMI, WC, and ST significantly affected the incidence of hypertension as they were separately analyzed (all P < 0.0001; crude HR: 2.445, 2.335, and 1.828; and HR 95% CI: 2.220-2.693, 2.011-2.712, and 1.636-2.042, respectively). For females, %BFs estimated by BMI, WC, and ST were the determinants of the development of hypertension whether covariates were adjusted or not (all P < 0.0001). In conclusion, there was a poor and ineffective association of %BF estimated by triceps skinfold thickness with the development of hypertension, especially when three %BFs were analyzed together. High %BFs estimated by BMI and WC were the true and effective predictors of the incidence of hypertension.

Body composition and arterial stiffness in pediatric patients with chronic kidney disease

BACKGROUND

This study investigated the impact of body composition in the arterial stiffness of children with chronic kidney disease (CKD).

METHODS

Fat mass (FM), fat tissue index (FTI), fat-free mass (FFM), fat-free tissue index (FFTI), and FFTI/FTI were measured in 26 patients and 25 healthy controls by bio-impedance analysis. Data on patient's body mass index (BMI) for height-age, serum albumin, glomerular filtration rate (GFR), blood pressure status, and pulse wave velocity (PWV) were collected in patients.

RESULTS

Patients presented lower levels of FM and FFM compared to healthy controls (p = 0.04 and p = 0.055 respectively). In patient group, BMI height-age z-score was positively correlated to FTI (r² = 0.574, p < 0.001) and FFTI (r² = 0.338, p = 0.001) and negatively correlated to FFTI/FTI (r² = 0.263, p = 0.007). Serum albumin was positively correlated only with FFM among body composition data (r² = 0.169, p = 0.037). PWV z-score was positively correlated to FFTI (r² = 0.421, p = 0.006) and inversely correlated to FFTI/FTI ≥ 2.5 (r² = 0.317, p = 0.003). Patients with FFTI/FTI ≥ 2.5 presented lower levels of PWV regardless the need for antihypertensive treatment. Serum albumin ≥ 3.8 mg/dl and FFTI/FTI ≥ 2.5 were independently associated with a lower risk for high PWV, after adjustment for age, sex, and GFR (OR 0.009, 95% CI 0.000-0.729 and OR 0.039, 95% CI 0.002-0.680). All underweight [2 (7.7%)] and overweight [4 (15.4%)] patients presented high PWV. Among normal weight patients, FFTI/FTI ratio ≥ 2.5 was significantly associated with lower PWV z-score (p = 0.013).

CONCLUSIONS

Both underweight and overweight are associated with arterial stiffness. Targeting FFTI/FTI ≥ 2.5 could be protective against cardiovascular disease in normal weight children.

Body fat indicators perform better than body mass index in identifying abnormal lipid profiles in boys but not in girls

BACKGROUND

BMI as a body weight indicator, may inadequately represent the biological effect of body fat on lipid profiles. This study aims to assess whether body fat indicators were superior to BMI for recognizing children with dyslipidemia.

METHODS

A nationwide cross-sectional study involving 8944 pediatric participants aged 6-18 years. Measures of fat mass index (FMI), fat mass percentage (FMP), BMI, and four lipid profiles were obtained.

RESULTS

Among boys, the standard multi-linear regression coefficients of FMI for TC, LDL-C, and TG were higher than those of BMI (P < 0.01), but not for HDL-C. Also, the prevalence ratios and area under curves (AUCs) of excess fat classified by FMI for specific abnormal lipid profiles (except for HDL-C) were greater than overweight classified by BMI. The AUCs for detecting children with abnormal TC, LDL-C, and TG of FMI-based excess fat were 3.9%, 5.6%, and 2.8% higher than those of BMI-based overweight, respectively, all P < 0.01. Among girls, the associations of BMI with lipid profiles were substantially similar to FMI. All these results were almost identical when FMP was used instead of FMI.

CONCLUSIONS

DXA measured body fat performs better than BMI in identifying abnormal lipid profiles in boys but not in girls.

Adiposity measures and their validity in estimating risk of hypertension in South Asian children: a cross-sectional study

OBJECTIVE

Given the South Asian phenotype of higher body fat at similar body mass index (BMI) relative to Caucasians, we sought to explore the association between prominent adiposity indicators with blood pressure (BP) and hypertension, to compare the accuracy of these indicators in estimating hypertension, and to provide cut-off values associated with adverse hypertension risk in South Asian children.

DESIGN

Cross-sectional study.

SETTING

Community-based recruitment in two Canadian cities (Hamilton and Surrey).

PARTICIPANTS

South Asian children (n=762) were recruited from two Canadian cities. Waist circumference, waist to height ratio and BMI were determined. Body fat percentage was assessed by bioelectrical impedance analysis and BP was assessed using an automated device. All variables (except body fat percentage) were transformed to z-scores using published standards.

OUTCOME MEASURES

Linear and Poisson regression was used to explore associations between the adiposity indicators with BP z-score and hypertension. Receiver operating curve (ROC) analysis was used to explore the strength of the adiposity indicators in estimating hypertension risk and sex-stratified optimal adiposity cut-off values associated with hypertension risk.

RESULTS

Significant associations were detected in adjusted and unadjusted models between the adiposity indicators with BP z-score and hypertension (p<0.01 for all). The area under the curve (AUC) values for the adiposity indicators for boys and girls ranged from 0.74 to 0.80, suggesting that the adiposity indicators are fair measures of estimating hypertension risk. Sex-stratified cut-off associated with adverse risk of hypertension for girls and boys, respectively, were at the 92nd and 82nd percentile for BMI z-scores, 65th and 80th percentile for WC z-score, 63rd and 67th percentile for WHtR z-score and at 29.8% and 23.5% for body fat.

CONCLUSION

Our results show associations between adiposity indicators with BP and hypertension and suggests that South Asian children might be at adverse risk of hypertension at levels of adiposity considered normal.

Age- and Sex-Related Percentiles of Skinfold Thickness, Waist and Hip Circumference, Waist-to-Hip Ratio and Waist-to-Height Ratio: Results from a Population-Based Pediatric Cohort in Germany (LIFE Child)

BACKGROUND

Skinfold thickness (ST), waist circumference (WC) and hip circumference (HC) measurements are simple methods for assessing fat tissue at defined body parts. We examined these parameters in a cohort of healthy children and adolescents in Leipzig. Our study provides current percentile curves for biceps, triceps, subscapular and iliac crest ST, plus WC, HC, waist-to-hip ratio and waist-to-height ratio.

METHODS

6,344 visits were recorded involving 2,363 individuals from 3 to 16 years in age. Continuous age- and gender-related percentiles (3rd, 10th, median, 90th, 97th percentiles) were estimated using Cole's LMS method.

RESULTS

For biceps and triceps ST, boys show a peak at the beginning of adolescence with a subsequent decrease, while percentile values among girls rise across the age range. Subscapular and iliac crest percentiles also show increasing curves with disproportionately high values for P90 and P97. Boys show higher values of WC, girls have higher levels of HC. WC and HC median percentiles constantly increase in both sexes with a plateau at the age of 16 for girls.

CONCLUSION

Trends for all parameters of body fat are in line with other national and international studies. Unlike the KiGGS study, our study provides circumference data across the whole of our age range, i.e. from 3 to 16 years.

A comparison of body mass index and percent body fat as predictors of cardiovascular risk factors

BACKGROUND

Cardiovascular disease (CVD) is an important cause of global mortality and morbidity. Body mass index (BMI) is the measure of adiposity that is used most frequently in CVD risk algorithms.

AIMS

We aimed to assess the relationship between several CVD risk factors (RFs) and percent body fat (PBF), and to compare the predictive values obtained using PBF for these cardiovascular RFs with the values obtained using BMI. The CVD RFs included, hypertension (HTN), diabetes mellitus (DM) and the presence of dyslipidemia (DLP).

METHODS AND MATERIALS

The data were derived from the MASHAD study, a cohort study of 9704 volunteers, aged 35-65 years and living in the city of Mashhad. Based on BMI and PBF values, subjects were classified into 4 groups; group 1 (low or normal BMI and PBF, N = 1670), group 2 (low or normal BMI but high PBF, N = 992), group 3 (high BMI and low or normal PBF, N = 837), and group 4 (high BMI and PBF, N = 6245). Chi-square, covariance and logistic regression were used to analyze the data at a significance level of 0.05.

RESULTS

There was an increasing trend from group 1 to group 4 for the mean values of all CVD RFs and their prevalence. There were significant differences in the frequency of a low HDL-C, this was substantially higher in Group 3 (38.6% in Group 3 versus 12.2% in Group 2); the frequency of a high serum TG (24% in Group 3 versus 9.9% in Group 2) and the frequency of dyslipidemia overall (56.2% in Group 3 and 28.8% in Group 2) (P-value<0.001 for all comparisons). The frequency of hypertension (22.9% in Group 3 versus 16.2% in Group 2) and IFG (8.5% in Group 3 versus 5.0% in Group 2) were also substantially higher in Group 3 compared to Group 2 (P-value<0.001 for both comparisons). All the mean values for the RFs were higher in group 3 from group 2 except HDL-C. When Group 1 was used as a reference and calculated OR of any RF for any group 2-4 rather than group 1, OR for all RF in group 3 was higher from group 2.

CONCLUSION

The differences in frequency, means and OR of RFs between Groups 2 and 3 showed a differential impact of a high BMI or high PBF. Compared to PBF, BMI may be a better predictor for several RFs for CVD.

Body mass index, waist circumference, body fat mass, and risk of developing hypertension in normal-weight children and adolescents

BACKGROUND AND AIMS

We prospectively examined the association between three adiposity indices, including body mass index (BMI), waist circumference (WC), and percentage of body fat (PBF), and risk of hypertension in normal-weight Chinese children.

METHODS AND RESULTS

The current study included 1526 (713 boys and 813 girls) normal-weight Chinese children (age 6-14 years old), who were free of hypertension at baseline (2014). Heights, body weight, WC, and PBF (estimated by bioelectrical impedance analysis) were measured at the baseline. Blood pressure was repeatedly measured in 2014, 2015 and 2016. Hypertension was defined as either high systolic blood pressure and/or high diastolic blood pressure, according to age- and sex-specific 95th percentile for Chinese children. We used Cox proportional hazards model to calculate the association between exposures and hypertension. We identified 88 incident hypertension cases during two years of follow up. High BMI was associated with high risk of developing hypertension after adjusting for potential confounders. The adjusted hazard ratio for hypertension was 2.88 (95% CI: 1.24, 6.69) comparing two extreme BMI quartiles. Each SD increase of BMI (≈1.85 kg/m²) was associated with a 32% higher likelihood to developing hypertension (Hazard ratio = 1.32; 95% CI: 1.003, 1.73). In contrast, we did not find significant associations between WC or PBF and higher hypertension risk (p-trend >0.2 for both).

CONCLUSION

High BMI, but not WC and PBF, was associated with high risk of hypertension in normal-weight Chinese children.

Body composition and cardiometabolic health: the need for novel concepts

It seems reasonable that overweight and obesity should be defined based on body composition rather than indirect indices like BMI or waist circumference. The use of conventional parameters like fat mass or visceral fat is however of similar and limited value for disease risk prediction at the population level and does not contribute much beyond the use of simple BMI or waist circumference. This conundrum may be partly explained by using complex phenotypes (e.g., Metabolic Syndrome or whole body insulin resistance) rather than more disease-specific outcomes like liver- and muscle insulin resistance. In addition, there are multifactorial causes of similar body composition phenotypes that may add to explain the variance in metabolic consequences of these phenotypes. An intriguing hypothesis is that fat mass represents the metabolic load that interacts with fat-free mass that stands for metabolic capacity to determine disease risk. This concept has important implications for assessment of healthy growth and development and when it is challenged with weight gain in adults. Integration of body composition information at the whole body, organ-tissue and cellular level is not required to improve the diagnosis of obesity but facilitates a better understanding of the etiology of obesity-associated metabolic complications.

Association of Body Fat Mass and Fat Distribution With the Incidence of Hypertension in a Population-Based Chinese Cohort: A 22-Year Follow-Up

BACKGROUND

There have been few studies on the association between the incidence of hypertension and the presence and distribution of body fat. The aim of this article was to evaluate this association.

METHODS AND RESULTS

Data were obtained from the China Health Nutrition Survey, a 22-year cohort study of 12 907 participants. Body mass index and triceps skinfold thickness were used as markers of body fat, whereas waist circumference (WC) was used as a marker of fat distribution. Cox regression was used to examine the association of body mass index, WC, and skinfold thickness with the incidence of hypertension. The interval between the baseline and hypertension diagnosis was the time variable, and hypertension was the end event. The mean age and proportion of men and women were 38.29 and 38.03 years and 45.63% and 54.37%, respectively. Compared with normal WC, abdominal obesity was associated with hypertension (P<0.001; crude hazard ratio, 2.11; 95% confidence interval, 1.89-2.37). Similarly, overweight (crude hazard ratio, 1.75; 95% confidence interval, 1.64-1.87) and obesity (crude hazard ratio, 3.19; 95% confidence interval, 2.80-3.63) were risk factors for hypertension (all P<0.001). When stratified by sex, the results confirmed that WC and body mass index predicted the development of hypertension in both men and women but not skinfold thickness in women.

CONCLUSIONS

Body mass index and WC were independent risk factors for hypertension, but skinfold thickness was a poor marker of body fat and could not be used to predict hypertension.

Childhood obesity treatment; Effects on BMI SDS, body composition, and fasting plasma lipid concentrations

OBJECTIVE

The body mass index (BMI) standard deviation score (SDS) may not adequately reflect changes in fat mass during childhood obesity treatment. This study aimed to investigate associations between BMI SDS, body composition, and fasting plasma lipid concentrations at baseline and during childhood obesity treatment.

METHODS

876 children and adolescents (498 girls) with overweight/obesity, median age 11.2 years (range 1.6-21.7), and median BMI SDS 2.8 (range 1.3-5.7) were enrolled in a multidisciplinary outpatient treatment program and followed for a median of 1.8 years (range 0.4-7.4). Height and weight, body composition measured by dual-energy X-ray absorptiometry, and fasting plasma lipid concentrations were assessed at baseline and at follow-up. Lipid concentrations (total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), non-HDL, and triglycerides (TG)) were available in 469 individuals (264 girls). Linear regressions were performed to investigate the associations between BMI SDS, body composition indices, and lipid concentrations.

RESULTS

At baseline, BMI SDS was negatively associated with concentrations of HDL (p = 6.7*10-4) and positively with TG (p = 9.7*10-6). Reductions in BMI SDS were associated with reductions in total body fat percentage (p<2*10-16) and percent truncal body fat (p<2*10-16). Furthermore, reductions in BMI SDS were associated with improvements in concentrations of TC, LDL, HDL, non-HDL, LDL/HDL-ratio, and TG (all p <0.0001). Changes in body fat percentage seemed to mediate the changes in plasma concentrations of TC, LDL, and non-HDL, but could not alone explain the changes in HDL, LDL/HDL-ratio or TG. Among 81 individuals with available lipid concentrations, who increased their BMI SDS, 61% improved their body composition, and 80% improved their lipid concentrations.

CONCLUSION

Reductions in the degree of obesity during multidisciplinary childhood obesity treatment are accompanied by improvements in body composition and fasting plasma lipid concentrations. Even in individuals increasing their BMI SDS, body composition and lipid concentrations may improve.

Fat Mass Index and Body Mass Index Affect Peak Metabolic Equivalent Negatively during Exercise Test among Children and Adolescents in Taiwan

Peak metabolic equivalent (MET) is the most reliable indicator of cardiorespiratory fitness (CRF). The aim of this study was to examine the association between CRF indicated by peak MET and body mass index (BMI) or fat mass index (FMI) in Taiwanese children and adolescents (C-A). Data of 638 C-A aged 10–18 that received symptom-limited treadmill exercise testing was analyzed. Anthropometry-body composition was measured by vector bioelectrical impedance analysis. BMI was defined as body weight (kg)/body height (m)² and FMI was defined as fat mass (kg)/body height (m)². BMI was grouped by Taiwanese obesity cut-off points. FMI Class-I was categorized by percentage of body fat. FMI Class-II used the reference values from Korean C-A. Excess adiposity was defined as (1) “overweight” and “obesity” by BMI, (2) greater than the sex- and age-specific 75th percentile of whole subjects by FMI Class-I, and (3) greater than 95th percentiles of reference value by FMI Class-II. Boys had significantly higher fat mass and FMI, and had more excess adiposity than girls (all p < 0.05). Both boys and girls with excess adiposity (by any definition) had lower MET at anaerobic threshold (AT MET) and peak MET (all p < 0.001). BMI and FMI were significantly negatively associated with both AT MET and peak MET significantly (all p < 0.001). FMI (95% CI: −0.411~−0.548) correlated with peak MET more than BMI (95% CI: −0.134~ −0.372) did. Excess adiposity affected CRF negatively. It is concluded that weight management should start early in childhood.

Associations between general and central obesity and hypertension among children: The Childhood Obesity Study in China Mega-Cities

In this study, we examined the associations of general and central obesity and hypertension among Chinese children. Data was collected from 1626 children aged 7-16 years and their parents in four mega-cities across China. Mixed effect models examined associations of general and central obesity with hypertension, and between body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). The prevalence of general obesity, central obesity, and hypertension among the children was 11.1%, 19.7%, and 9.0%, respectively. More boys had general and central obesity than girls (15.2% vs. 6.9%; 27.4% vs. 11.7%, respectively; both P < 0.0001). Sex difference in hypertension rate was not statistically significant (9.3% in boys vs. 8.8% in girls, P = 0.7341). Both SBP and DBP were positively associated with BMI, WC, and WHtR, regardless of sex and region. General obesity (OR = 5.94, 95% confidence interval [CI]: 3.69-9.55) and central obesity (OR = 3.45, 95% CI: 2.27-5.23) were strongly associated with hypertension. The prevalence of general obesity, central obesity, and hypertension was high among Chinese children in the four mega-cities across China. Children's BMI, WC, and WHtR were positively associated with their SBP and DBP. Obese children were 3-6 times more likely to have hypertension.

Changing Characteristics of Obese Children and Adolescents Entering Pediatric Lifestyle Intervention Programs in Germany over the Last 11 Years: An Adiposity Patients Registry Multicenter Analysis of 65,453 Children and Adolescents

OBJECTIVE

To examine whether characteristics of children and adolescents who start lifestyle intervention (LI) for obesity in Germany changed over the last decade.

METHODS

65,453 subjects (<21 years) from the APV database (Adiposity Patients Registry) with a BMI ≥ 90th percentile were included (years 2005-2015). Logistic regression models (confounders: age, sex, migration background) were created for overweight, obesity, extreme obesity, and obesity-related comorbidities. Comorbidities were further adjusted for weight category. Results were stratified by inpatient or outpatient care.

RESULTS

Extreme obesity was found to be more frequent at the onset of LI (2005: 11.6; 2015: 12.7%) with a similar trend in subgroups (p < 0.001). Obesity increased (2005: 50.3%; 2015: 55.1%), and overweight decreased (2005: 34.1%; 2015: 29.0%) in the whole study population. Trends were similar for inpatient or outpatient care (all p < 0.001). Hypertension increased from 45.7% to 49.2% in the whole study population, and similar data were obtained in the subgroup of inpatients (both p < 0.0001). Dyslipidemia increased in all patients (2005: 21.9%; 2015: 28.0%) and in inpatients (2005: 20.2%; 2015: 25.7%; both p < 0.0001). Abnormal carbohydrate metabolism rose in all patients (from 5.2 to 6.4%; p = 0.0002) without significant trends in subgroups.

CONCLUSION

During the last decade, children and adolescents presented with higher BMI SDS at the onset of LI and the proportion with obesity-related comorbidities increased. Particularly the presence of comorbidities differed between outpatients and inpatients.

Lean, but not healthy: the 'metabolically obese, normal-weight' phenotype

PURPOSE OF REVIEW

Obesity is commonly associated with metabolic dysfunction but there are obese persons who are metabolically healthy. On the opposite side of the coin, there are lean persons who carry multiple cardiometabolic risk factors, typically referred to as metabolically obese, normal-weight (MONW). This has called into question our understanding of obesity and metabolic dysfunction, as an appearance of normal weight may mask significant comorbidities and delay health interventions.

RECENT FINDINGS

High heterogeneity in MONW prevalence rates has been observed, with estimates ranging from as low as 5% to as high as 45%. Reasons for this include sample size effects, differences in MONW definition, social and demographic factors, as well as assumptions made in establishing normal weight. MONW study participants are often characterized by excess visceral adipose tissue and ectopic fat deposition, adipose tissue inflammation, altered inflammatory and adipokine profiles, reduced skeletal muscle mass and low cardiorespiratory fitness. However, more often than not, groups of MONW study participants have been somewhat 'fatter' than the control groups of metabolically healthy lean study participants, which in itself could be responsible for some of the observed differences. Very limited data are available regarding interventions to improve metabolic function in MONW study participants.

SUMMARY

There is a need for more research to better understand the characteristics of the MONW phenotype, the cause of metabolic dysfunction in the absence of obesity, and evaluate potential therapies so as to facilitate the establishment of clinical guidelines.

Performance of Two Bioelectrical Impedance Analyses in the Diagnosis of Overweight and Obesity in Children and Adolescents: The FUPRECOL Study

This study aimed to determine thresholds for percentage of body fat (BF%) corresponding to the cut-off values for overweight/obesity as recommended by the International Obesity Task Force (IOTF), using two bioelectrical impedance analyzers (BIA), and described the likelihood of increased cardiometabolic risk in our cohort defined by the IOTF and BF% status. Participants included 1165 children and adolescents (54.9% girls) from Bogotá (Colombia). Body mass index (BMI) was calculated from height and weight. BF% of each youth was assessed first using the Tanita BC-418^® followed by a Tanita BF-689^®. The sensitivity and specificity of both devices and their ability to correctly classify children as overweight/obesity (≥2 standard deviation), as defined by IOTF, was investigated using receiver operating characteristic (ROC) by sex and age groups (9–11, 12–14, and 13–17 years old); Area under curve (AUC) values were also reported. For girls, the optimal BF% threshold for classifying into overweight/obesity was found to be between 25.2 and 28.5 (AUC = 0.91–0.97) and 23.9 to 26.6 (AUC = 0.90–0.99) for Tanita BC-418^® and Tanita BF-689^®, respectively. For boys, the optimal threshold was between 16.5 and 21.1 (AUC = 0.93–0.96) and 15.8 to 20.6 (AUC = 0.92–0.94) by Tanita BC-418^® and Tanita BF-689^®, respectively. All AUC values for ROC curves were statistically significant and there were no differences between AUC values measured by both BIA devices. The BF% values associated with the IOTF-recommended BMI cut-off for overweight/obesity may require age- and sex-specific threshold values in Colombian children and adolescents aged 9–17 years and could be used as a surrogate method to identify individuals at risk of excess adiposity.

Comparison of body mass index with abdominal obesity for identifying elevated blood pressure in children and adolescents: The SNEC study

Body mass index (BMI) and waist circumference (WC) are two common ways to measure obesity. There is a debate, however, about which of these two measures are more closely associated with elevated blood pressure (BP). The aim of this study is to investigate the prevalence of obesity and whether BMI and WC is better associated with elevated BP in children and adolescents. A representative sample of 8613 Chinese youth aged 7-17 years from seven cities in Northeastern China was selected and measurements of height, weight, WC, BP were taken from 2012 to 2013. The average age of the children was 11.3±2.3years. The prevalence of overweight/obese and abdominal obesity in the subjects was 35% and 44.8%, respectively. We found that both BMI and WC were significantly associated with elevated BP. An increase of 1kgm^-2 in BMI was associated with a 1.10 (1.08-1.12, 95% CI) increased risk of an elevated BP diagnosis in boys, and a 1.14 (1.11-1.16, 95% CI) increased risk in girls. Meanwhile, a 1cm increase in WC correlated with a 1.03 (1.02-1.04, 95% CI) and a 1.05 (1.04-1.06, 95% CI) increased risk of higher BP in boys and girls, respectively. Compared to the normal-weight youth, subjects with elevated BMI (BMI>85th) had higher risk of elevated BP (OR: 2.42, 95% CI: 2.13-2.75) than that of in elevated WC participants (OR: 2.00, 95% CI: 1.77-2.27). Therefore, BMI may associate better with elevated BP than WC in Chinese youth in our Seven Northeastern Cities study.