BMI and an anthropometry-based estimate of fat mass percentage are both valid discriminators of cardiometabolic risk: a comparison with DXA and bioimpedance

Body composition in adults born preterm with very low birth weight

BACKGROUND

Studies on body composition in preterm very low birth weight (VLBW < 1500 g) survivors are inconsistent and trajectories later in life unknown. We assessed body composition and its change from young to mid-adulthood in VLBW adults.

METHODS

We studied 137 VLBW adults and 158 term-born controls from two birth cohorts in Finland and Norway at mean age 36 years. Body composition was assessed by 8-polar bioelectrical impedance. We compared results with dual-energy x-ray absorptiometry measurements at 24 years.

RESULTS

In mid-adulthood, VLBW women and men were shorter than controls. Fat percentage (mean difference in women 1.1%; 95% CI, -1.5% to 3.5%, men 0.8%; -2.0% to 3.6%) and BMI were similar. VLBW women had 2.9 (0.9 to 4.8) kg and VLBW men 5.3 (2.7 to 8.1) kg lower lean body mass than controls, mostly attributable to shorter height. Between young and mid-adulthood, both groups gained fat and lean body mass (p for interaction VLBW x age>0.3).

CONCLUSION

Compared with term-born controls, VLBW adults had similar body fat percentage but lower lean body mass, largely explained by their shorter height. This could contribute to lower insulin sensitivity and muscular fitness previously found in VLBW survivors and predispose to functional limitations with increasing age.

IMPACT

In mid-adulthood, individuals born preterm with very low birth weight had similar body fat percentage but lower lean body mass than those born at term. This was largely explained by their shorter height. First study to report longitudinal assessments of body size and composition from young to mid-adulthood in very low birth weight adults. Lower lean body mass in very low birth weight adults could contribute to lower insulin sensitivity and muscular fitness and lead to earlier functional limitations with increasing age.

Development and validation of new bioelectrical impedance equations to accurately estimate fat mass percentage in a heterogeneous Caucasian population

Fat mass percentage (%FM) is frequently determined by nutritionists and personal trainers with bioelectrical impedance analysis (BIA) devices. The aims of the present study were: (1) to develop new regression equations using dual-energy X-ray absorptiometry (DXA) as the reference method for estimating %FM in a heterogeneous Caucasian population with a foot-to-hand device (BIA-101) and a hand-to-hand device (BIA-TELELAB) and (2) to compare the new equations with the manufacturers' equations. We hypothesized that the new equations would lead to more accurate estimations compared with DXA. A total of 218 healthy Caucasian participants aged 18 to 65 years were divided into a development group and a validation group. The accuracy of the different equations was assessed by mean differences, coefficient of determination, standard error of the estimate (SEE), intraclass correlation coefficients (ICC), and Bland-Altman plots. The proposed equation for BIA-101 explained 90.0% of the variance in the DXA-derived %FM, with a low random error (SEE = 2.98%), excellent agreement (ICC = 0.94), no fixed bias, and relatively low individual variability (5.86%). For BIA-TELELAB, the proposed equation explained 88.0% of the variance in the DXA-derived %FM, with a low random error (SEE = 3.27%), excellent agreement (ICC = 0.93), no fixed bias, and relatively low individual variability (6.37%). The results obtained for the manufacturers' equations confirm that these equations are not a good option for %FM assessment. As hypothesized, the new regression equations for BIA-101 and BIA-TELELAB devices can accurately estimate %FM in a heterogeneous Caucasian population with a broad age range.

Overfat cutoffs and the optimal combination of body fat indices for detecting cardiometabolic risk among school-aged children

OBJECTIVE

This study aimed to develop cutoffs and the optimal combination for body fat indices for screening cardiometabolic risk (CMR) among the pediatric population.

METHODS

This cross-sectional study consisted of 8710 (50.3% boys) Chinese children aged 6 to 18 years. Body fat indices, including fat mass index (FMI), body fat percentage, trunk to leg fat ratio (TLR), and android to gynoid fat ratio, were derived from dual-energy x-ray absorptiometry scans. The area under the receiver operating characteristic curve was used to determine the best combination and optimal cutoffs of body fat indices to identify CMR.

RESULTS

Compared with anthropometry-based obesity measures, i.e., BMI and waist circumference, the FMI + TLR combination presented statistically higher area under the receiver operating characteristic curve values for discriminating CMR and its clustering. The optimal overfat cutoffs of FMI and TLR were respectively determined at the 75th percentile in boys and at the 80th percentile of FMI and the 75th percentile of TLR in girls. Moreover, simplified thresholds derived from age-group-merged cutoffs showed similar performance as optimal cutoffs in detecting CMR.

CONCLUSIONS

Both the optimal and simplified overfat cutoffs were provided for the Chinese pediatric population. The use of FMI and TLR together allows for adequate screening of CMR and its clustering.

A comparison of associations of body mass index and dual-energy x-ray absorptiometry measured percentage fat and total fat with global serum metabolites in young women

OBJECTIVE

Body mass index (BMI) does not directly measure adiposity, whereas dual-energy x-ray absorptiometry (DXA) provides valid direct estimates of adiposity. Therefore, this study evaluated usefulness of BMI as a measure of adiposity in serum metabolomics studies.

METHODS

A cross-sectional analysis was conducted of 202 women aged 25 to 29 years in the Dietary Intervention Study in Children Follow-Up Study. Heights and weights were measured, and body composition was quantified using clinical DXA protocols. Serum metabolomic profiling was performed by liquid chromatography-tandem mass spectrometry. Partial correlations of BMI, percentage fat (%FAT), and total fat (TOTFAT) with log transformed serum metabolites were calculated.

RESULTS

There was significant overlap in the 93 metabolites that correlated with BMI, %FAT, and/or TOTFAT; 9 differently correlated with BMI and %FAT, whereas 15 differently correlated with BMI and TOTFAT. Even for these metabolites, absolute differences were modest. Metabolite set enrichment analysis identified diacylglycerol and sphingolipid metabolism as overrepresented among metabolites significantly correlated with all three measures of adiposity.

CONCLUSIONS

BMI can be a good proxy for DXA measured %FAT and TOTFAT in descriptive metabolomic studies of healthy, young White women. Larger studies in more diverse populations are needed to endorse more generalized conclusions.

Diagnosis, Prevalence and Significance of Obesity in a Cohort of CKD Patients

BACKGROUND

data regarding the association between obesity and morbidity/mortality in patients with chronic kidney disease (CKD) are uncertain and sometimes contradictory. The aims of our study were to determine the associations among different measures of obesity and adiposity, and the risk of all-cause mortality or dialysis entry in stage 3-5 CKD patients.

MATERIALS

this observational cohort study included 178 CKD patients followed for a median of 71 months. Biochemistry, anthropometric measures such as body mass index (BMI), waist-to-hip ratio, mid-arm muscle circumference (MAMC) and body composition by bioimpedance analysis were evaluated.

RESULTS

we found a weak agreement between BMI and other measures of adiposity. In multivariable regression analysis, all measures of obesity such as BMI, waist circumference and waist-to-height ratio were not associated with dialysis entry and/or mortality. Instead, MAMC was associated with dialysis entry HR 0.82 [95% CI: 0.75-0.89] and high FM% with mortality HR 2.08 [95% CI: 1.04-4.18].

CONCLUSIONS

in our CKD population, lower MAMC was predictive of dialysis commencing, while a higher percentage of fatty mass was a predictor of mortality. Instead, obesity, as defined by BMI, is not associated with dialysis commencing or all-cause mortality.

Bioimpedance and Dual-Energy X-ray Absorptiometry Are Not Equivalent Technologies: Comparing Fat Mass and Fat-Free Mass

Bioimpedance (BIA) is the most frequently used technology for body composition assessment at a daily clinical level, mostly due to its low price and user-friendly operation. However, many doubts persist regarding its physiological meaning and applicability. The present study aimed to compare one BIA system and the Dual-Energy X-ray Absorptiometry (DXA) for the characterization of body composition in a previously selected cohort of healthy adult participants. A descriptive observational cross-sectional study included a final sample of 121 participants, 93 women and 28 men, with a mean age of 28.26 ± 9.72 years old and a mean body mass index (BMI) of 22.68 ± 3.13 kg/m². Statistics involved paired t-tests and agreement analysis by the Bland-Altman method. BIA underestimated the percent body fat (%BF) by 5.56% and overestimated Fat-Free Mass (FFM) by 2.90 kg. A strong positive correlation between both technologies was found for FFM (r = 0.980) and the %BF (r = 0.932), but the disagreement was statistically significant (p < 0.001). Although DXA and BIA seem to correlate, these technologies are not congruent. Therefore, the risk of (mis)interpretation and bias is clear with BIA, potentially impacting the nutritional planning of clinical dietitians and the further results of its patients.

Establishing a Reference Interval for an Estimate of Peripheral Insulin Resistance in a Group of Iraqi People

Background and aims: Insulin resistance (IR) is the cornerstone in pathophysiology of T2DM. Identifying people with IR can slow the progress to diabetes. Triglyceride and glucose index (TyG index) is a simple tool to assess IR without insulin measurement. This study aims at establishing the reference interval for TyG index in apparently healthy Iraqis. Material and method: This study involved (77) apparently healthy adults (41 men and 36 women) in Mosul, Iraq. Fasting Serum lipids, glucose and insulin were measured and BMI was calculated. The modified TyG index was calculated and compared to other surrogate measures of IR and its reference interval was calculated. Results: TyG index values were normally distributed and significantly correlated with HOMA-IR, Mc-Auley index, QUICKI, and triglycerides/ HDL-c index (r= 0.322, p= 0.004; r=-0.68, p<0001; r= -0.29, p=0.01; r=0.84, p<0.0001respectively). ANOVA and PostHoc Duncan’s analyses revealed significant differences in mean TyG between (lean people) and (overweight and obese subjects), (p=0.02). BMI- based TyG reference intervals were calculated as (4.11- 4.91) and (4.25- 5.05) respectively. This is the first study in Iraq to set a reference interval for TyG index. Values should be interpreted according to BMI.  

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.

Long-term effects of premature birth on somatic development in women through adolescence and adulthood

Objectives

To evaluate the long-term consequences of preterm birth on anthropometric parameters in women in adolescence and into adulthood.

Methods

Seventy girls born preterm (age 12.22 ± 1.52 years) and 48 born at term participated in the first stage. Eighteen years later, 13 of the same women participated in a follow-up and were compared with a control group of 27 women. We compared anthropometric results across the two examinations, and in the second stage, also assessed body composition using bioelectrical impedance analysis.

Results

No significant differences were found in anthropometric parameters or the content of individual components of the body between the preterm-born and control groups. However, the preterm-born group showed a tendency for higher average fat mass and lower fat-free and soft lean mass compared with the control group, and had a significantly higher mean waist–hip ratio.

Conclusions

Preterm birth does not adversely affect somatic development in girls during adolescence, but shows a correlation with an elevated waist–hip ratio in adulthood.

Dual Energy X-Ray Absorptiometry Compared with Anthropometry in Relation to Cardio-Metabolic Risk Factors in a Young Adult Population: Is the 'Gold Standard' Tarnished?

Background and Aims

Assessment of adiposity using dual energy x-ray absorptiometry (DXA) has been considered more advantageous in comparison to anthropometry for predicting cardio-metabolic risk in the older population, by virtue of its ability to distinguish total and regional fat. Nonetheless, there is increasing uncertainty regarding the relative superiority of DXA and little comparative data exist in young adults. This study aimed to identify which measure of adiposity determined by either DXA or anthropometry is optimal within a range of cardio-metabolic risk factors in young adults.

Methods and Results

1138 adults aged 20 years were assessed by DXA and standard anthropometry from the Western Australian Pregnancy Cohort (Raine) Study. Cross-sectional linear regression analyses were performed. Waist to height ratio was superior to any DXA measure with HDL-C. BMI was the superior model in relation to blood pressure than any DXA measure. Midriff fat mass (DXA) and waist circumference were comparable in relation to glucose. For all the other cardio-metabolic variables, anthropometric and DXA measures were comparable. DXA midriff fat mass compared with BMI or waist hip ratio was the superior measure for triglycerides, insulin and HOMA-IR.

Conclusion

Although midriff fat mass (measured by DXA) was the superior measure with insulin sensitivity and triglycerides, the anthropometric measures were better or equal with various DXA measures for majority of the cardio-metabolic risk factors. Our findings suggest, clinical anthropometry is generally as useful as DXA in the evaluation of the individual cardio-metabolic risk factors in young adults.

Bioelectrical impedance vector analysis for evaluating zinc supplementation in prepubertal and healthy children

BACKGROUND

The prevalence of abnormal nutritional status has increased in children and adolescents. Nutritional assessment is important for monitoring the health and nutritional status. Bioelectrical impedance vector analysis (BIVA) combines changes in tissue hydration and structure and body composition that can be assessed.

OBJECTIVES

The objective of this study was to use BIVA to evaluate nutritional status in 60 prepubertal children, aged between 8 and 9 years, supplemented with zinc, to detect possible changes in body composition.

DESIGN

We performed a randomized, controlled, triple-blind study. The children were divided into the control group (CG; sorbitol 10%, n=29) or the experimental group (EG; 10 mg Zn/day, n=31), and the duration of the experiment was 3 months. Anthropometric assessments were performed for all of the children.

RESULTS

The body mass index-for-age increased after oral zinc supplementation in the EG (p=0.005). BIVA indicated that the CG demonstrated a tendency for dehydration and decreased soft tissue and the EG demonstrated a tendency for increased soft tissue, primarily the fat-free mass. After analyses of BIVA ellipses, we observed that this method could detect improvements in body composition in healthy children supplemented with zinc.

CONCLUSIONS

These results suggest that BIVA could be an auxiliary method for studying a small population undergoing zinc intervention.

Body mass index in early and middle adult life: prospective associations with myocardial infarction, stroke and diabetes over a 30-year period: the British Regional Heart Study

OBJECTIVES

Adiposity in middle age is an established risk factor for cardiovascular disease and type 2 diabetes; less is known about the impact of adiposity from early adult life. We examined the effects of high body mass index (BMI) in early and middle adulthood on myocardial infarction (MI), stroke and diabetes risks.

DESIGN

A prospective cohort study.

PARTICIPANTS

7735 men with BMI measured in middle age (40-59 years) and BMI ascertained at 21 years from military records or participant recall.

PRIMARY AND SECONDARY OUTCOME MEASURES

30-year follow-up data for type 2 diabetes, MI and stroke incidence; Cox proportional hazards models were used to examine the effect of BMI at both ages on these outcomes, adjusted for age and smoking status.

RESULTS

Among 4846 (63%) men (with complete data), a 1 kg/m(2) higher BMI at 21 years was associated with a 6% (95% CI 4% to 9%) higher type 2 diabetes risk, compared with a 21% (95% CI 18% to 24%) higher diabetes risk for a 1 kg/m(2) higher BMI in middle age (hazard ratio (HR) 1.21, 95% CI 1.18 to 1.24). Higher BMI in middle age was associated with a 6% (95% CI 4% to 8%) increase in MI and a 4% (95% CI 1% to 7%) increase in stroke; BMI at 21 years showed no associations with MI or stroke risk.

CONCLUSIONS

Higher BMI at 21 years of age is associated with later diabetes incidence but not MI or stroke, while higher BMI in middle age is strongly associated with all outcomes. Early obesity prevention may reduce later type 2 diabetes risk, more than MI and stroke.

The efficacy of Bioelectrical Impedance Analysis (BIA) in monitoring body composition changes during treatment of restrictive eating disorder patients

REVIEWS

Treating restrictive eating disorder patients is metabolically and psychologically complex. Determining body composition is an important diagnostic and treatment option for these patients, because it ascertains whether the acquisition of body mass during refeeding is metabolically appropriate - ideally an approximate 20/80% - 25/75% fat/lean body mass ratio. The purpose of this paper is to evaluate the efficacy of Bioelectrical Impedance Analysis (BIA) during the treatment period of patients with restrictive eating disorders. The search engines PubMed, Medline, and MSN were utilized using combinations of key words, "Bioimpedance Analysis", "body composition determination", "eating disorders", and "anorexia".

CONCLUSIONS

The literature indicates that the use of Bioelectrical Impedance Analysis (BIA) in eating disorder patients to be efficacious in determining body composition during the treatment period, and that only assessing weight changes does not necessarily reflect specific changes in various body compartments. Also, utilizing BIA has the advantage of using each patient as his/her own "control", potentially allowing for a more individualized nutrition regimen according to the body composition changes observed during treatment.