A population-based approach to define body-composition phenotypes

Reference Centiles for the Evaluation of Nutritional Status in Children using Body Fat Percentage, Fat Mass and Lean Body Mass Index

BACKGROUND

Body fat percentage (BF%), fat mass index (FMI), and lean body mass index (LBMI) are often used to evaluate the nutritional status of children. Until now, no pediatric FMI reference centiles are applicable for GE Healthcare Lunar DXA systems. The aim of the study was to generate age-specific BF%, FMI, and LBMI references centiles for GE Healthcare Lunar DXA systems.

METHODOLOGY

Published values from the National Health and Nutrition Examination Survey 1999-2004 (age 8-20 years) were used to generate the reference centiles for the non-Hispanic black, non-Hispanic white, and Mexican American NHANES population. The LMS and LMSP methods were used to generate the reference centiles.

RESULTS

Data of 2433 non-Hispanic black children (972 females), 2026 non-Hispanic white children (873 females), and 2547 Mexican American children (1010 females) were eligible.

CONCLUSIONS

We presented age-specific reference centiles for BF%, FMI, and LBMI for children and adolescents which were ethnicity specific (non-Hispanic black, non-Hispanic white, and Mexican American) and directly applicable to Prodigy and iDXA GE Healthcare Lunar systems with software version 14.0. We proposed the use of BF%, FMI, and LBMI together to evaluate nutritional status in children.

Influence of sarcopenia on bone health parameters in a group of eumenorrheic obese premenopausal women

INTRODUCTION

The aim of this study was to compare bone mineral density (BMD) and geometric indices of hip bone strength in a group of obese sarcopenic premenopausal women (n = 27) and a group of obese premenopausal women with normal appendicular lean mass (ALM)/body mass index ratio (BMI) (n = 26).

MATERIALS AND METHODS

The ALM/BMI criterion of The Foundation for the National Institute of Health was used; women with an ALM/BMI ratio < 0.512 m² were considered obese sarcopenic. Body composition and bone variables were measured by DXA. DXA measurements were completed for the whole body (WB), lumbar spine (L1-L4), total hip (TH) and femoral neck (FN). Hip geometry parameters including cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (Z), strength index (SI) and buckling ratio (BR) were derived by DXA.

RESULTS

Age, weight and BMI were not significantly different between the two groups. Height, lean mass, skeletal muscle mass index, ALM and the ratio ALM/BMI were significantly higher in obese women with normal ALM/BMI ratio compared to obese sarcopenic women. Fat mass percentage was significantly higher in obese sarcopenic women compared to obese women with normal ALM/BMI ratio. WB BMC, TH BMD, FN BMD, CSA, CSMI and Z were significantly higher in obese women with normal ALM/BMI ratio compared to obese sarcopenic women. In the whole population (n = 53), ALM and the ratio ALM/BMI were positively correlated to WB BMC, CSA, CSMI and Z.

CONCLUSION

The present study suggests that sarcopenia negatively influences bone mineral density and hip geometry parameters before menopause in eumenorrheic obese women.

Reference Values for Skeletal Muscle Mass - Current Concepts and Methodological Considerations

Assessment of a low skeletal muscle mass (SM) is important for diagnosis of ageing and disease-associated sarcopenia and is hindered by heterogeneous methods and terminologies that lead to differences in diagnostic criteria among studies and even among consensus definitions. The aim of this review was to analyze and summarize previously published cut-offs for SM applied in clinical and research settings and to facilitate comparison of results between studies. Multiple published reference values for discrepant parameters of SM were identified from 64 studies and the underlying methodological assumptions and limitations are compared including different concepts for normalization of SM for body size and fat mass (FM). Single computed tomography or magnetic resonance imaging images and appendicular lean soft tissue by dual X-ray absorptiometry (DXA) or bioelectrical impedance analysis (BIA) are taken as a valid substitute of total SM because they show a high correlation with results from whole body imaging in cross-sectional and longitudinal analyses. However, the random error of these methods limits the applicability of these substitutes in the assessment of individual cases and together with the systematic error limits the accurate detection of changes in SM. Adverse effects of obesity on muscle quality and function may lead to an underestimation of sarcopenia in obesity and may justify normalization of SM for FM. In conclusion, results for SM can only be compared with reference values using the same method, BIA- or DXA-device and an appropriate reference population. Limitations of proxies for total SM as well as normalization of SM for FM are important content-related issues that need to be considered in longitudinal studies, populations with obesity or older subjects.

Reference values of body composition parameters and visceral adipose tissue (VAT) by DXA in adults aged 18-81 years-results from the LEAD cohort

Background

Increasing attention has been drawn on the assessment of body composition phenotypes, since the distribution of soft tissue influences cardio-metabolic risk. Dual-energy X-ray absorptiometry (DXA) is a validated technique to assess body composition. European reference values from population-based cohorts are rare.

Aims

To provide age- and sex-related reference values of body composition parameters and visceral adipose tissue (VAT) mass, and for lean mass index (LMI) with regard to fat mass index (FMI) quantities and BMI categories.

Methods

GE-Lunar Prodigy DXA scans of 10.894 participants, aged 18–81 years, recruited from 2011 to 2019 by the Austrian LEAD study, a population-based cohort study, have been used to construct reference curves using the LMS method. Parameters assessed are FMI, LMI, appendicular LMI, fat mass ratios android/gynoid and trunk/limbs, and VAT.

Results

All lean mass and fat mass parameters indicating central fat accumulation were higher in men, whereas other fat mass indices were higher in women. LMI differed between each FMI subgroup (low vs. normal, low vs. high, normal vs. high), and BMI category in all ages and LMI increased with FMI and BMI classes. VAT mass was higher in men compared with women and increased across all age groups within both sexes.

Conclusion

The present study provides age- and sex-related reference values for European adults aged 18–81 years for body composition parameters and VAT mass for Lunar Prodigy DXA. In addition, this study reports LMI reference values with regard to fat mass quantities, showing a positive association with increasing FMI percentiles and BMI categories.

Longitudinal Changes of Body Composition Phenotypes and Their Association with Incident Type 2 Diabetes Mellitus during a 5-Year Follow-up in Koreans

BACKGROUND

To elucidate longitudinal changes of complex body composition phenotypes and their association with incident type 2 diabetes mellitus.

METHODS

A total of 17,280 (mean age, 48.1±8.2 years) Korean adults who underwent medical check-ups were included. The mean follow-up duration was 5.5±0.5 years. Body compositions were assessed using a bioelectrical impedance analysis. Four body composition phenotypes were defined using the median of appendicular skeletal muscle mass (ASM) index and fat mass index: low muscle/low fat (LM/LF); high muscle (HM)/LF; LM/high fat (HF); and HM/HF groups.

RESULTS

Of the individuals in the LM/LF or HM/HF groups, over 60% remained in the same group, and over 30% were moved to the LM/HF group. Most of the LM/HF group remained in this group. In the baseline HM/LF group, approximately 30% stayed in the group, and the remaining individuals transitioned to the three other groups in similar proportions. Incident diabetes was significantly lower in participants who remained in the HM/LF group than those who transitioned to the LM/LF or LM/HF group from the baseline HM/LF group in men. ASM index was significantly associated with a decreased risk for incident diabetes in men regardless of obesity status (adjusted odds ratio [OR], 0.71 per kg/m²; 95% confidence interval [CI], 0.52 to 0.97 in non-obese) (adjusted OR, 0.87; 95% CI, 0.77 to 0.98 in obese) after adjusting for other strong risk factors (e.g., baseline glycosylated hemoglobin and homeostasis model assessment of insulin resistance).

CONCLUSION

Maintenance of ASM may be protective against the development of type 2 diabetes mellitus in men, regardless of obesity status.

Accuracy of Resting Energy Expenditure Predictive Equations in Patients With Cancer

BACKGROUND

Our purpose was to assess the accuracy of resting energy expenditure (REE) equations in patients with newly diagnosed stage I-IV non-small cell lung, rectal, colon, renal, or pancreatic cancer.

METHODS

In this cross-sectional study, REE was measured using indirect calorimetry and compared with 23 equations. Agreement between measured and predicted REE was assessed via paired t-tests, Bland-Altman analysis, and percent of estimations ≤ 10% of measured values. Accuracy was measured among subgroups of body mass index (BMI), stage (I-III vs IV), and cancer type (lung, rectal, and colon) categories. Fat mass (FM) and fat-free mass (FFM) were assessed using dual x-ray absorptiometry.

RESULTS

Among 125 patients, most had lung, colon, or rectal cancer (92%, BMI: 27.5 ± 5.6 kg/m² , age: 61 ± 11 years, REE: 1629 ± 321 kcal/d). Thirteen (56.5%) equations yielded REE values different than measured (P < 0.05). Limits of agreement were wide for all equations, with Mifflin-St. Jeor equation having the smallest limits of agreement, -21.7% to 11.3% (-394 to 203 kcal/d). Equations with FFM were not more accurate except for one equation (Huang with body composition; bias, limits of agreement: -0.3 ± 11.3% vs without body composition: 2.3 ± 10.1%, P < 0.001). Bias in body composition equations was consistently positively correlated with age and frequently negatively correlated with FM. Bias and limits of agreement were similar among subgroups of patients.

CONCLUSION

REE cannot be accurately predicted on an individual level, and bias relates to age and FM.

Body composition indices in Brazilian adults: age-specific and sex-specific percentile curves

OBJECTIVE

To establish percentile curves for measures and indices of body composition by age and sex and compare them with data from other ethnic groups.

SUBJECTS AND METHODS

Cross-sectional, population-based study with adults aged 20-59 years (n = 689). Percentile curves adjusted by a third degree polynomial function were constructed for skeletal mass index (SMI), fat mass index, body fat, and load-capacity metabolic indices (LCMI) based on dual-energy X-ray absorptiometry (DXA).

RESULTS

SMIweight and SMIBMI showed decline from the third decade of life in both sexes, whereas SMIheight was not able to identify lean mass loss over the ages studied. There was a slight drop at the end of the fifth decade (50-59 years) in men. Among Americans and Chinese, the 50th percentile curve of SMIheight showed an earlier decline. The estimates of adiposity and LCMI curves peaked between 40-49 years and Americans and Chinese maintained an upward curve throughout adulthood.

CONCLUSION

The data and curves showed that the SMI adjusted for BMI and body weight were more adequate in detecting the decline of lean mass in adults due to aging. In contrast, SMIheight had a positive correlation with age and its curve increased throughout the evaluated age groups. The results contribute to the evaluation to the nutritional status of adults and to the prevention and treatment of outcomes related to adiposity and deficit lean mass.

The pathogenesis of obesity

Body fat mass increases when energy intake exceeds energy expenditure. In the long term, a positive energy balance will result in obesity. The worldwide prevalence of obesity has increased dramatically, posing a serious threat to human health. Therefore, insight in the pathogenesis of obesity is important to identify novel prevention and treatment strategies. This review describes the physiology of energy expenditure and energy intake in the context of body weight gain in humans. We focus on the components of energy expenditure and the regulation of energy intake. Finally, we describe rare monogenetic causes leading to an impairment in central regulation of food intake and obesity.

Comparisons of different indices of low muscle mass in relationship with cardiometabolic disorder

This study aimed to evaluate the most valid index among various indices of low muscle mass in assessing cardiometabolic risks in a Korean population. Appendicular lean mass index (ALMI, kg/m2), fat mass index (FMI, kg/m2), FMI-adjusted ALMI (ALMfmi), ratio of ALM to weight index (ALMwt), ratio of ALM to body mass index (ALMbmi) and ratio of ALM to truncal fat index (ALMtrunkfat) were measured by dual energy X-ray absorptiometry in 17,870 participants from 2008 to 2011. We adopted all the aforementioned indices of low muscle mass expressed as sex- and age-specific standard deviation scores (Z-scores). Low muscle mass for age was defined as Z-score <-1. The prevalence of low muscle mass was approximately 16% across all indices. Low muscle mass defined by ALMI had low muscle mass and low fat mass, and ALMfmi had low muscle mass at the same FMI. However, low muscle mass defined by ALMwt, ALMbmi and ALMtrunkfat had similar muscle mass with high FMI. The receiver operating characteristic curve in metabolic syndrome showed that the ALMtrunkfat was 0.74 in male and 0.69 in female, indicating that ALMtrunkfat was the best discrimination index for metabolic syndrome. This study showed that ALMtrunkfat could be a useful indicator for screening cardiometabolic risk factors, particularly in normal or overweight Asian population.

Body Composition Technology: Implications for the ICU

Malnutrition continues to be highly prevalent in hospitalized and critically ill patients and is associated with significant morbidity and mortality. Additionally, survivors of critical illness have an increased risk for sarcopenia, which leads to weakness and physical debilitation that can persist for years. Nutrition risk assessment tools have been developed and validated in critically ill patients but have limitations. Variables such as body weight, body mass index, weight change, or percentage of food intake can be difficult to obtain in critically ill patients and may be misleading given changes in body composition, such as an increase in body water. Assessment of body composition through new techniques provides a unique opportunity to counter some of these limitations and develop improved methods of nutrition risk assessment based on objective data. The present manuscript provides a review of the most commonly available clinical technology for assessment of body composition (bioimpedance, computed tomography, and ultrasound), including data from trials in critically ill patients highlighting the benefits and weaknesses of each modality.

Implications of low muscle mass across the continuum of care: a narrative review

Abnormalities in body composition can occur at any body weight. Low muscle mass is a predictor of poor morbidity and mortality and occurs in several populations. This narrative review provides an overview of the importance of low muscle mass on health outcomes for patients in inpatient, outpatient and long-term care clinical settings. A one-year glimpse at publications that showcases the rapidly growing research of body composition in clinical settings is included. Low muscle mass is associated with outcomes such as higher surgical and post-operative complications, longer length of hospital stay, lower physical function, poorer quality of life and shorter survival. As such, the potential clinical benefits of preventing and reversing this condition are likely to impact patient outcomes and resource utilization/health care costs. Clinically viable tools to measure body composition are needed for routine screening and intervention. Future research studies should elucidate the effectiveness of multimodal interventions to counteract low muscle mass for optimal patient outcomes across the healthcare continuum. Key messages Low muscle mass is associated with several negative outcomes across the healthcare continuum. Techniques to identify and counteract low muscle mass in clinical settings are needed.

Epidemiology and determinants of type 2 diabetes in south Asia

Type 2 diabetes has rapidly developed into a major public health problem in south Asia (defined here as Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka) in recent decades. During this period, major lifestyle changes associated with economic transition, industrialisation, urbanisation, and globalisation have been key determinants in the increasing burden of non-communicable diseases. A decline in nutrition quality, reduced physical activity, and increased sedentary behaviours are reflected in the increasing prevalence of type 2 diabetes and related risk factors in the region. The International Diabetes Federation 2017 estimates of the prevalence of diabetes in adults in the region range from 4·0% in Nepal to 8·8% in India. The prevalence of overweight ranges from 16·7% in Nepal to 26·1% in Sri Lanka, and the prevalence of obesity ranges from 2·9% in Nepal to 6·8% in Sri Lanka. An increasing proportion of children, adolescents, and women are overweight or obese, leading to a heightened risk of type 2 diabetes. Ethnic south Asians present with greater metabolic risk at lower levels of BMI compared with other ethnic groups (referred to as the south Asian phenotype), with type 2 diabetes often developing at a younger age, and with rapid progression of diabetic complications. Because of the presence of multiple risk factors and a body composition conducive to the development of type 2 diabetes, south Asians should be aggressively targeted for prevention. In this Series paper, we detail trends in the prevalence of diabetes in the region and address major determinants of the disease in the context of nutrition and physical activity transitions and the south Asian phenotype.

Body composition-related functions: a problem-oriented approach to phenotyping

AIM

The objective of this study is to generate metabolic phenotypes based on structure-function relationships.

METHODS

In 459 healthy adults (54% females, 18 and 40 years old), we analyzed body composition by air-displacement densitometry (to assess fat mass, (FM) and fat-free mass (FFM)) and whole-body magnetic resonance imaging (to assess skeletal muscle mass (SMM) and masses of brain, heart, liver, kidneys, and subcutaneous (SAT) and visceral adipose tissue (VAT)), resting energy expenditure (REE) by indirect calorimetry, and plasma concentrations of insulin (Ins) and leptin (Lep).

RESULTS

Three "functional body composition-derived phenotypes" (FBCPs) were derived: (1) REE on FFM-FBCP, (2) Lep on FM-FBCP, and (3) Ins on VAT-FBCP. Assuming that being within the ± 5% range of the respective regression lines reflects a "normal" structure-function relationship, three "normal" FBCPs were generated with prevalences of 9.0%, 5.1%, and 6.8%, respectively, of the study population. The three "FBCPs" did not overlap and were independent from each other. When compared with the two other FBCPs, the "Lep on FM-FBCP" was leanest, whereas the "REE on FFM-FBCP" had the highest BMI and SAT. Taking into account FFM composition, a hierarchical multi-level model is proposed with brain at level 1, the liver at level 2, and SMM and FM at level 3 with insulin coordinating the interplay between level 1 and 2, whereas variance in plasma insulin levels impacts energy and substrate metabolism in SMM and AT.

CONCLUSION

Structure-function relationships can be used to generate FBCPs. Different FBCPs reflect different dimensions of normality (or health). This is evidence for the idea that there is no across the board "normal" state.

Developing a toolkit for the assessment and monitoring of musculoskeletal ageing

The complexities and heterogeneity of the ageing process have slowed the development of consensus on appropriate biomarkers of healthy ageing. The Medical Research Council–Arthritis Research UK Centre for Integrated research into Musculoskeletal Ageing (CIMA) is a collaboration between researchers and clinicians at the Universities of Liverpool, Sheffield and Newcastle. One of CIMA’s objectives is to ‘Identify and share optimal techniques and approaches to monitor age-related changes in all musculoskeletal tissues, and to provide an integrated assessment of musculoskeletal function’—in other words to develop a toolkit for assessing musculoskeletal ageing. This toolkit is envisaged as an instrument that can be used to characterise and quantify musculoskeletal function during ‘normal’ ageing, lend itself to use in large-scale, internationally important cohorts, and provide a set of biomarker outcome measures for epidemiological and intervention studies designed to enhance healthy musculoskeletal ageing. Such potential biomarkers include: biochemical measurements in biofluids or tissue samples, in vivo measurements of body composition, imaging of structural and physical properties, and functional tests. This review assesses candidate biomarkers of musculoskeletal ageing under these four headings, details their biological bases, strengths and limitations, and makes practical recommendations for their use. In addition, we identify gaps in the evidence base and priorities for further research on biomarkers of musculoskeletal ageing.

The impact of sarcopenic obesity on knee and hip osteoarthritis: a scoping review

BACKGROUND

The progressive, debilitating nature of knee and hip osteoarthritis can result in severe, persistent pain and disability, potentially leading to a need for total joint arthroplasty (TJA) in end-stage osteoarthritis. TJA in adults with obesity is associated with increased surgical risk and prolonged recovery, yet classifying obesity only using body mass index (BMI) precludes distinction of obesity phenotypes and their impact on surgical risk and recovery. The sarcopenic obesity phenotype, characterized by high adiposity and low skeletal muscle mass, is associated with higher infection rates, poorer function, and slower recovery after surgery in other clinical populations, but not thoroughly investigated in osteoarthritis. The rising prevalence and impact of this phenotype demands further attention in osteoarthritis treatment models of care, particularly as osteoarthritis-related pain, disability, and current treatment practices may inadvertently be influencing its development.

METHODS

A scoping review was used to examine the extent of evidence of sarcopenic obesity in adults with hip or knee osteoarthritis. Medline, CINAHL, Web of Science and EMBASE were systematically searched from inception to December 2017 with keywords and subject headings related to obesity, sarcopenia and osteoarthritis.

RESULTS

Eleven studies met inclusion criteria, with indications that muscle weakness, low skeletal muscle mass or sarcopenia are present alongside obesity in this population, potentially impacting therapeutic outcomes, and TJA surgical risk and recovery.

CONCLUSIONS

Consideration of sarcopenic obesity should be included in osteoarthritis patient assessments.

Poor Physical Function as a Marker of Sarcopenia in Adults with Class II/III Obesity

BACKGROUND

Adults with class II/III obesity [body mass index (in kg/m2) ≥35] may present with a phenotype characterized by low lean mass and excess fat mass, a condition known as sarcopenic obesity (SO). Little is known about the prevalence and relevance of SO in these individuals, primarily due to a lack of relevant diagnostic criteria.

OBJECTIVE

Here, we explored the definition of SO based on physical function as an outcome of interest in adults with class II/III obesity and applied this definition to compare clinical characteristics between SO and non-SO patients.

METHODS

In this cross-sectional analysis, patients' demographic, anthropometric, and biochemical characteristics, as well as comorbidities and physical activity levels, were collected at an obesity specialty clinic prior to any treatment. Body composition was assessed by dual-energy X-ray absorptiometry. Physical function was assessed by self-reported difficulties with activities of daily living (ADLs) from an 11-item questionnaire. Five SO definitions were tested against reported difficulty with ADLs with the use of receiver operating characteristic (ROC) analysis.

RESULTS

A total of 120 subjects (86% women) aged 46 ± 11 y were included. Based on ROC analysis, SO was best defined by an appendicular skeletal mass (ASM)/weight x 100 (%) <19.35% for women and <24.33% for men, resulting in a prevalence of 25% (n = 30, women 22.3%, men 41.2%). SO was significantly associated with older age, higher waist circumference, higher triglycerides, greater use of antihypertensive medications, and lower physical activity.

CONCLUSIONS

In this sample of adults with class II/III obesity, difficulties with ADLs were best associated with measures of ASM in relation to total body weight. Patients identified with SO using this criterion presented with poorer clinical outcomes such as factors of elevated cardiometabolic risk.

Sarcopenic obesity and overall mortality: Results from the application of novel models of body composition phenotypes to the National Health and Nutrition Examination Survey 1999-2004

BACKGROUND/OBJECTIVES

There is no consensus on the definition of sarcopenic obesity (SO), resulting in inconsistent associations of SO with mortality risk. We aim to evaluate association of dual energy x-ray absorptiometry (DXA) SO models with mortality risk in a US adult population (≥50 years).

SUBJECTS/METHODS

The study population consisted of 3577 participants aged 50 years and older from the 1999-2004 National Health and Nutrition and Examination Survey with mortality follow-up data through December 31, 2011. Difference in survival time in people with and without SO defined by three body composition DXA models (Model 1: body composition phenotype model; Model 2: Truncal Fat Mass (TrFM)/Appendicular Skeletal Muscle Mass (ASM) ratio model; Model 3: Fat Mass (FM)/Fat Free Mass (FFM) ratio). The differences between the models were assessed by the acceleration failure time model, and expressed as time ratios (TR).

RESULTS

Participants age 50-70 years with SO had a significantly decreased survival time, according to the body composition phenotype model (TR: 0.92; 95% CI: 0.87-0.97), and TrFM/ASM ratio model (TR: 0.88; 95% CI: 0.81-0.95). The FM/FFM ratio model did not detect significant differences in survival time. Participants with SO aged 70 years and older did not have a significantly decreased survival time, according to all three models.

CONCLUSIONS

A SO phenotype increases mortality risk in people of age 50-70 years, but not in people aged 70 years and older. The application of the body composition phenotype and the TrFM/ASM ratio models may represent useful diagnostic approaches to improve the prediction of disease and mortality risk.

Functional correlates of detailed body composition in healthy elderly subjects

Methods of body composition analysis are now widely used to characterize health status, i.e., nutritional status, metabolic rates, and cardiometabolic risk factors. However, the functional correlates of individual body components have not been systematically analyzed. In this study, we have used a two-compartment model, which was assessed by air displacement plethysmography. Detailed body composition was measured by whole body magnetic resonance imaging in a healthy population of 40 Caucasians, aged 65–81 yr (20 men; body mass index range: 18.6–37.2 kg/m2). Physical, metabolic, as well as endocrine functions included pulmonary function, handgrip strength, gait speed, sit-to-stand test, physical activity, blood pressure, body temperature, resting energy expenditure (REE), liver and kidney functions (glomerular filtration rate), insulin sensitivity [homeostasis model assessment (HOMA)], plasma lipids, plasma leptin, testosterone, dehydroepiandrosterone, insulin-like growth factor I levels, thyroid status, vitamins, and inflammation. Individual body compartments were intercorrelated, e.g., skeletal muscle mass (SM) correlated with visceral adipose tissue ( r = 0.53) and kidneys ( r = 0.62). For the functional correlates, SM ( r = 0.58) and liver volume ( r = 0.63) were associated with REE, SM correlated with handgrip strength ( r = 0.57), and kidneys with glomerular filtration rate ( r = 0.57). While visceral adipose tissue correlated with HOMA ( r = 0.59), subcutaneous adipose tissue was related to plasma leptin levels ( r = 0.84). The subcutaneous adipose tissue-to-leptin relationship was moderated by inflammation increasing the explained variance of leptin levels by 4.0%. In linear regression analysis, detailed body composition explained variances in REE (75.0%), HOMA (41.0%), and leptin (78.0%) compared with a body mass index-based model (REE 16.0%, HOMA 31.0%, leptin 45.0%). In addition, detailed body composition explained 39.0% of the variance in kidney function.

NEW & NOTEWORTHY BCA should be used to address specific body functions only. In clinical practice, there is need of a clear focus on the specific research question related to physical, metabolic, or endocrine functions.

Differential Aging Signals in Abdominal CT Scans

RATIONALE AND OBJECTIVES

Changes in the composition of body tissues are major aging phenotypes, but they have been difficult to study in depth. Here we describe age-related change in abdominal tissues observable in computed tomography (CT) scans. We used pattern recognition and machine learning to detect and quantify these changes in a model-agnostic fashion.

MATERIALS AND METHODS

CT scans of abdominal L4 sections were obtained from Baltimore Longitudinal Study of Aging (BLSA) participants. Age-related change in the constituent tissues were determined by training machine classifiers to differentiate age groups within male and female strata ("Younger" at 50-70 years old vs "Older" at 80-99 years old). The accuracy achieved by the classifiers in differentiating the age cohorts was used as a surrogate measure of the aging signal in the different tissues.

RESULTS

The highest accuracy for discriminating age differences was 0.76 and 0.72 for males and females, respectively. The classification accuracy was 0.79 and 0.71 for adipose tissue, 0.70 and 0.68 for soft tissue, and 0.65 and 0.64 for bone.

CONCLUSIONS

Using image data from a large sample of well-characterized pool of participants dispersed over a wide age range, we explored age-related differences in gross morphology and texture of abdominal tissues. This technology is advantageous for tracking effects of biological aging and predicting adverse outcomes when compared to the traditional use of specific molecular biomarkers. Application of pattern recognition and machine learning as a tool for analyzing medical images may provide much needed insight into tissue changes occurring with aging and, further, connect these changes with their metabolic and functional consequences.

Body composition by DXA

Body composition measurements from DXA have been available since DXA technology was developed 30years ago, but are historically underutilized. Recently, there have been rapid developments in body composition assessment including the analysis and publication of representative data for the US, official usage guidance from the International Society for Clinical Densitometry, and development of regional body composition measures with clinical utility. DXA body composition is much more than whole body percent fat. In this paper celebrating 30years of DXA for body composition, we will review the principles of DXA soft tissue analysis, practical clinical and research applications, and what to look for in the future.

Fat mass to fat-free mass ratio reference values from NHANES III using bioelectrical impedance analysis

BACKGROUND & AIM

Low fat-free mass (FFM) or high fat mass (FM) are abnormal body composition phenotypes associated with morbidity. These conditions in combination lead to worse health outcomes, and can be identified by a high FM/FFM ratio. Here, we developed sex, age, and body mass index (BMI) stratified, population-based FM/FFM reference values using bioelectrical impedance analysis (BIA) measurements.

METHODS

White, non-Hispanic individuals aged 18-90 years old with data for weight, stature and BIA resistance measures from the third National Health and Nutrition Examination Survey (NHANES) III were included. Previously validated and sex-specific BIA prediction equations were used to calculate FM and FFM. FM/FFM values were generated at 5th, 50th and 95th percentiles for each sex, age (18-39.9, 40-59.9, 60-69.9 and 70-90 years), and BMI category (underweight, normal weight, overweight, class I/II and class III obesity).

RESULTS

A total of 6372 individuals who had estimated FM and FFM values were identified (3366 females, 3006 males). Median values of FM/FFM were 0.24 and 0.40 for young (≤39.9 years) males and females with normal BMI, and 0.34 for males and 0.59 for females who were overweight. For elderly individuals aged >70 years, median FM/FFM for males and females were respectively 0.28 and 0.45 for those with normal BMI, and 0.37 and 0.61 for those in the overweight category.

CONCLUSIONS

These FM/FFM reference values provide information on body composition characteristics that account for age, sex and BMI, which can be useful to identify individuals at risk for body composition abnormalities.

Body Composition Is Altered in Pre-Diabetic Patients With Impaired Fasting Glucose Tolerance: Results From the NHANES Survey

BACKGROUND

Previous studies suggest that type 2 diabetes mellitus (T2DM) is associated with a loss of muscle mass but the impact of fasting blood glucose (FBG) on body composition remains underappreciated in pre-diabetic subjects. The aim of this study was to determine the influence of FBG on lean mass (LM), fat mass (FM) and their distribution (trunk vs. appendicular), separately in middle-aged men and women.

METHODS

One thousand nine hundred and eleven (1,911) men (63.9 ± 11.7 years) and 1,977 women (63.7 ± 12.1 years) from the National Health and Nutrition Examination Survey (1999 - 2004) were divided into four groups: normal glucose tolerance (NGT), low impaired fasting glucose (IFG), high IFG and T2DM. Body composition was obtained from dual X-ray absorptiometry (DXA).

RESULTS

Of the patients, 68.7% had NGT, 16.1% low IFG, 9.4% high IFG and 5.8% T2DM. After adjustment for age, body mass index, ethnicity, smoking, alcohol and physical activity (PA), no change in appendicular LM was observed between groups, but significant increases in trunk FM (in both gender) and trunk LM (in women) were found with increased glucose intolerance (T2DM > IFG > NGT), as well as significant decreases in trunk and total LM/FM ratios (T2DM < IFG < NGT) and a significant increase in trunk/appendicular FM ratio (T2DM > IFG > NGT).

CONCLUSIONS

Elevated FBG within the normal range is not associated with a significant loss of appendicular LM, but modifications in LM and FM trunk and total distribution with IFG suggest that nutritional and physical lifestyle strategies should be implemented in the pre-diabetic state.

Being fat and smart: A comparative analysis of the fat-brain trade-off in mammals

Humans stand out among non-aquatic mammals by having both an extremely large brain and a relatively large amount of body fat. To understand the evolution of this human peculiarity we report a phylogenetic comparative study of 120 mammalian species, including 30 primates, using seasonal variation in adult body mass as a proxy of the tendency to store fat. Species that rely on storing fat to survive lean periods are expected to be less active because of higher costs of locomotion and have increased predation risk due to reduced agility. Because a fat-storage strategy reduces the net cognitive benefit of a large brain without reducing its cost, such species should be less likely to evolve a larger brain than non-fat-storing species. We therefore predict that the two strategies to buffer food shortages (storing body fat and cognitive flexibility) are compensatory, and therefore predict negative co-evolution between relative brain size and seasonal variation in body mass. This trade-off is expected to be stronger in predominantly arboreal species than in more terrestrial ones, as the cost of transporting additional adipose depots is higher for climbing than for horizontal locomotion. We did, indeed, find a significant negative correlation between brain size and coefficient of variation (CV) in body mass in both sexes for the subsample of arboreal species, both in all mammals and within primates. In predominantly terrestrial species, in contrast, this correlation was not significant. We therefore suggest that the adoption of habitually terrestrial locomotor habits, accompanied by a reduced reliance on climbing, has allowed for a primate of our body size the unique human combination of unusually large brains and unusually large adipose depots.

Study Design and Rationale for the Phase 3 Clinical Development Program of Enobosarm, a Selective Androgen Receptor Modulator, for the Prevention and Treatment of Muscle Wasting in Cancer Patients (POWER Trials)

Muscle wasting in cancer is a common and often occult condition that can occur prior to overt signs of weight loss and before a clinical diagnosis of cachexia can be made. Muscle wasting in cancer is an important and independent predictor of progressive functional impairment, decreased quality of life, and increased mortality. Although several therapeutic agents are currently in development for the treatment of muscle wasting or cachexia in cancer, the majority of these agents do not directly inhibit muscle loss. Selective androgen receptor modulators (SARMs) have the potential to increase lean body mass (LBM) and hence muscle mass, without the untoward side effects seen with traditional anabolic agents. Enobosarm, a nonsteroidal SARM, is an agent in clinical development for prevention and treatment of muscle wasting in patients with cancer (POWER 1 and 2 trials). The POWER trials are two identically designed randomized, double-blind, placebo-controlled, multicenter, and multinational phase 3 trials to assess the efficacy of enobosarm for the prevention and treatment of muscle wasting in subjects initiating first-line chemotherapy for non-small-cell lung cancer (NSCLC). To assess enobosarm's effect on both prevention and treatment of muscle wasting, no minimum weight loss is required. These pivotal trials have pioneered the methodological and regulatory fields exploring a therapeutic agent for cancer-associated muscle wasting, a process hereby described. In each POWER trial, subjects will receive placebo (n = 150) or enobosarm 3 mg (n = 150) orally once daily for 147 days. Physical function, assessed as stair climb power (SCP), and LBM, assessed by dual-energy X-ray absorptiometry (DXA), are the co-primary efficacy endpoints in both trials assessed at day 84. Based on extensive feedback from the US Food and Drug Administration (FDA), the co-primary endpoints will be analyzed as a responder analysis. To be considered a physical function responder, a subject must have ≥10 % improvement in physical function compared to baseline. To meet the definition of response on LBM, a subject must have demonstrated no loss of LBM compared with baseline. Secondary endpoints include durability of response assessed at day 147 in those responding at day 84. A combined overall survival analysis for both studies is considered a key secondary safety endpoint. The POWER trials design was established with extensive clinical input and collaboration with regulatory agencies. The efficacy endpoints are a result of this feedback and discussion of the threshold for clinical benefit in patients at risk for muscle wasting. Full results from these studies will soon be published and will further guide the development of future anabolic trials. Clinical Trial ID: NCT01355484. https://clinicaltrials.gov/ct2/show/NCT01355484 , NCT01355497. https://clinicaltrials.gov/ct2/show/NCT01355497?term=g300505&rank=1 .

Developing and Validating an Age-Independent Equation Using Multi-Frequency Bioelectrical Impedance Analysis for Estimation of Appendicular Skeletal Muscle Mass and Establishing a Cutoff for Sarcopenia

Background: Appendicular skeletal muscle (or lean) mass (ALM) estimated using dual-energy X-ray absorptiometry (DXA) is considered to be a preferred method for sarcopenia studies. However, DXA is expensive, has limited portability, and requires radiation exposure. Bioelectrical impedance analysis (BIA) is inexpensive, easy to use, and portable; thus BIA might be useful in sarcopenia investigations. However, a large variety of models have been commercially supplied by different companies, and for most consumer products, the equations estimating ALM are not disclosed. It is therefore difficult to use these equations for research purposes. In particular, the BIA equation is often age-dependent, which leads to fundamental difficulty in examining age-related ALM loss. The aims of the current study were as follows: (1) to develop and validate an equation to estimate ALM using multi-frequency BIA (MF-BIA) based on theoretical models, and (2) to establish sarcopenia cutoff values using the equation for the Japanese population. Methods: We measured height (Ht), weight, and ALM obtained using DXA and a standing-posture 8-electrode MF-BIA (5, 50, 250 kHz) in 756 Japanese individuals aged 18 to 86-years-old (222 men and 301 women as developing equation group and 97 men and 136 women as a cross validation group). The traditional impedance index (Ht²/Z₅₀) and impedance ratio of high and low frequency (Z₂₅₀/Z₅) of hand to foot values were calculated. Multiple regression analyses were conducted with ALM as dependent variable in men and women separately. Results: We created the following equations: ALM = (0.6947 × (Ht²/Z₅₀)) + (-55.24 × (Z₂₅₀/Z₅)) + (-10,940 × (1/Z₅₀)) + 51.33 for men, and ALM = (0.6144 × (Ht²/Z₅₀)) + (-36.61 × (Z₂₅₀/Z₅)) + (-9332 × (1/Z₅₀)) + 37.91 for women. Additionally, we conducted measurements in 1624 men and 1368 women aged 18 to 40 years to establish sarcopenia cutoff values in the Japanese population. The mean values minus 2 standard deviations of the skeletal muscle mass index (ALM/Ht²) in these participants were 6.8 and 5.7 kg/m² in men and women, respectively. Conclusion: The current study established and validated a theoretical and age-independent equation using MF-BIA to estimate ALM and provided reasonable sarcopenia cutoff values.

Obesity

Excessive fat deposition in obesity has a multifactorial aetiology, but is widely considered the result of disequilibrium between energy intake and expenditure. Despite specific public health policies and individual treatment efforts to combat the obesity epidemic, >2 billion people worldwide are overweight or obese. The central nervous system circuitry, fuel turnover and metabolism as well as adipose tissue homeostasis are important to comprehend excessive weight gain and associated comorbidities. Obesity has a profound impact on quality of life, even in seemingly healthy individuals. Diet, physical activity or exercise and lifestyle changes are the cornerstones of obesity treatment, but medical treatment and bariatric surgery are becoming important. Family history, food environment, cultural preferences, adverse reactions to food, perinatal nutrition, previous or current diseases and physical activity patterns are relevant aspects for the health care professional to consider when treating the individual with obesity. Clinicians and other health care professionals are often ill-equipped to address the important environmental and socioeconomic drivers of the current obesity epidemic. Finally, understanding the epigenetic and genetic factors as well as metabolic pathways that take advantage of 'omics' technologies could play a very relevant part in combating obesity within a precision approach.

Liposomes as colloidal nanovehicles: on the road to success in intravenous drug delivery

The advancement of research in colloidal systems has led to the increased application of this technology in more effective and targeted drug delivery. Nanotechnology enables control over functionality parameters and allows innovations in biodegradable, biocompatible, and stimuli-responsive delivery systems. The first closed bilayer phospholipid system, the liposome system, has been making steady progress over five decades of extensive research and has been efficient in achieving many desirable parameters such as remote drug loading, size-controlling measures, longer circulation half-lives, and triggered release. Liposome-mediated drug delivery has been successful in overcoming obstacles to cellular and tissue uptake of drugs with improved biodistribution in vitro and in vivo. These colloidal nanovehicles have moved on from a mere concept to clinical applications in various drug delivery systems for antifungal, antibiotic, and anticancer drugs.

Dual energy X-ray absorptiometry body composition reference values of limbs and trunk from NHANES 1999-2004 with additional visualization methods

Body Mass Index has traditionally been used as a measure of health, but Fat Mass Index (FMI) and Lean Mass Index (LMI) have been shown to be more predictive of mortality and health risk. Total body FMI and LMI reference curves have particularly been useful in quantifying sarcopenia and sarcopenic obesity. Research has shown regional composition has significant associations to health outcomes. We derived FMI and LMI reference curves of the regions of the body (leg, arm, and trunk) for 15,908 individuals in the 1999-2004 National Health and Nutrition Examination Survey data for each sex and ethnicity using the Lambda-Mu-Sigma (LMS) method and developed software to visualize this regional composition. These reference curves displayed differentiation between males and females during puberty and sharper limb LMI declines during late adulthood for males. For adults ages 30-50, females had 39%, 83%, and 47% larger arm, leg, and trunk FMI values than males, respectively. Males had 49%, 20%, and 15% higher regional LMI values than females for the arms, legs, and trunk respectively. The leg FMI and LMI of black females were 14% and 15% higher respectively than those of Hispanic and white females. White and Hispanic males had 37% higher trunk FMI values than black males. Hispanic females had 20% higher trunk FMI than white and black females. These data underscore the importance of accounting for sex and ethnicity in studies of regional composition. This study is the first to produce regional LMI and FMI reference tables and curves from the NHANES dataset. These reference curves provide a framework useful in studies and research involving sarcopenia, obesity, sarcopenic obesity, and other studies of compositional phenotypes. Further, the software tool we provide for visualizing regional composition will prove useful in monitoring progress in physical therapy, diets, or other attempts to attain healthier compositions.

Prevalence of Sarcopenic Obesity in Adults with Class II/III Obesity Using Different Diagnostic Criteria

Background/Objective. Sarcopenic obesity (SO) is a hidden condition of reduced lean soft tissue (LST) in context of excess adiposity. SO is most commonly reported in older adults and both its risk and prevalence increase with age. A variety of body composition indices and cut points have been used to define this condition, leading to conflicting prevalence and risk prediction. Here, we investigate variability in the prevalence of SO in an adult sample of individuals with class II/III obesity (BMI ≥ 35 kg/m2) using different diagnostic criteria. Methods. SO definitions were identified from a literature review of studies using dual-energy X-ray absorptiometry (DXA) to assess LST. Demographics, anthropometrics, and body composition (by DXA) were measured in n = 120, 86% female (46.9 ± 11.1 years). Results. LST was extremely variable in individuals, even with similar body sizes, and observed across the age spectrum. The prevalence of SO ranged from 0 to 84.5% in females and 0 to 100% in males, depending upon the definition applied, with higher prevalence among definitions accounting for measures of body size or fat mass. Conclusion. SO is present, yet variable, in adults with class II/III obesity. Accounting for body mass or fat mass may identify a higher number of individuals with SO, although risk prediction remains to be studied.

Validity of bioelectrical impedance analysis in estimation of fat-free mass in colorectal cancer patients

BACKGROUND & AIMS

Bioelectrical impedance analysis (BIA) is an accessible and cheap method to measure fat-free mass (FFM). However, BIA estimates are subject to uncertainty in patient populations with altered body composition and hydration. The aim of the current study was to validate a whole-body and a segmental BIA device against dual-energy X-ray absorptiometry (DXA) in colorectal cancer (CRC) patients, and to investigate the ability of different empiric equations for BIA to predict DXA FFM (FFM_DXA).

METHODS

Forty-three non-metastatic CRC patients (aged 50-80 years) were enrolled in this study. Whole-body and segmental BIA FFM estimates (FFM_{whole-bodyBIA}, FFM_segmentalBIA) were calculated using 14 empiric equations, including the equations from the manufacturers, before comparison to FFM_DXA estimates.

RESULTS

Strong linear relationships were observed between FFM_BIA and FFM_DXA estimates for all equations (R² = 0.94-0.98 for both devices). However, there were large discrepancies in FFM estimates depending on the equations used with mean differences in the ranges -6.5-6.8 kg and -11.0-3.4 kg for whole-body and segmental BIA, respectively. For whole-body BIA, 77% of BIA derived FFM estimates were significantly different from FFM_DXA, whereas for segmental BIA, 85% were significantly different. For whole-body BIA, the Schols* equation gave the highest agreement with FFM_DXA with mean difference ±SD of -0.16 ± 1.94 kg (p = 0.582). The manufacturer's equation gave a small overestimation of FFM with 1.46 ± 2.16 kg (p < 0.001) with a tendency towards proportional bias (r = 0.28, p = 0.066). For segmental BIA, the Heitmann* equation gave the highest agreement with FFM_DXA (0.17 ± 1.83 kg (p = 0.546)). Using the manufacturer's equation, no difference in FFM estimates was observed (-0.34 ± 2.06 kg (p = 0.292)), however, a clear proportional bias was detected (r = 0.69, p < 0.001). Both devices demonstrated acceptable ability to detect low FFM compared to DXA using the optimal equation.

CONCLUSION

In a population of non-metastatic CRC patients, mostly consisting of Caucasian adults and with a wide range of body composition measures, both the whole-body BIA and segmental BIA device provide FFM estimates that are comparable to FFM_DXA on a group level when the appropriate equations are applied. At the individual level (i.e. in clinical practice) BIA may be a valuable tool to identify patients with low FFM as part of a malnutrition diagnosis.

Comparison of World Health Organization and Asia-Pacific body mass index classifications in COPD patients

INTRODUCTION

A low body mass index (BMI) is associated with increased mortality and low health-related quality of life in patients with COPD. The Asia-Pacific classification of BMI has a lower cutoff for overweight and obese categories compared to the World Health Organization (WHO) classification. The present study assessed patients with COPD among different BMI categories according to two BMI classification systems: WHO and Asia-Pacific.

PATIENTS AND METHODS

Patients with COPD aged 40 years or older from the Korean COPD Subtype Study cohort were selected for evaluation. We enrolled 1,462 patients. Medical history including age, sex, St George's Respiratory Questionnaire (SGRQ-C), the modified Medical Research Council (mMRC) dyspnea scale, and post-bronchodilator forced expiratory volume in 1 second (FEV₁) were evaluated. Patients were categorized into different BMI groups according to the two BMI classification systems.

RESULT

FEV₁ and the diffusing capacity of the lung for carbon monoxide (DLCO) percentage revealed an inverse "U"-shaped pattern as the BMI groups changed from underweight to obese when WHO cutoffs were applied. When Asia-Pacific cutoffs were applied, FEV₁ and DLCO (%) exhibited a linearly ascending relationship as the BMI increased, and the percentage of patients in the overweight and obese groups linearly decreased with increasing severity of the Global Initiative for Chronic Obstructive Lung Disease criteria. From the underweight to the overweight groups, SGRQ-C and mMRC had a decreasing relationship in both the WHO and Asia-Pacific classifications. The prevalence of comorbidities in the different BMI groups showed similar trends in both BMI classifications systems.

CONCLUSION

The present study demonstrated that patients with COPD who have a high BMI have better pulmonary function and health-related quality of life and reduced dyspnea symptoms. Furthermore, the Asia-Pacific BMI classification more appropriately reflects the correlation of obesity and disease manifestation in Asian COPD patients than the WHO classification.

Relationships Between Anthropometric Measurements and Intraocular Pressure: The Korea National Health and Nutrition Examination Survey

PURPOSE

To evaluate the relationship between intraocular pressure (IOP) and various anthropometric measures.

DESIGN

A population-based cross-sectional study.

METHODS

A total of 5008 participants, 2080 men and 2928 women ≥19 years of age were included from the Korea National Health and Nutrition Examination Survey V database, focusing on the years 2010 and 2011. We selected IOP in the right eye of a normal healthy population as the outcome variable of our study. We analyzed the relationship between IOP and anthropometric parameters using dual-energy X-ray absorptiometry by sex. Lean body mass was calculated as total body mass minus fat mass. We used general linear models and logistic regression analysis to evaluate risk factors of high IOP. Our main outcome measure was correlation between anthropometric data and IOP.

RESULTS

In multivariate general linear models, greater body mass index (BMI) and waist circumference were correlated with higher IOP for both men (BMI, β = 0.053, P = .026; waist circumference, β = 0.016, P = .067) and women (BMI, β = 0.074, P < .001; waist circumference, β = 0.028, P < .001). Greater fat mass (β = 0.027, P = .037) and fat mass/lean body mass (β = 1.170, P = .06) were correlated with higher IOP, while greater lean body mass/weight (β = -3.188, P = .025), lean body mass/BMI (β = -1.379, P = .002), appendicular skeletal muscle mass/BMI (β = -2.270, P = .022), and bone mineral content/BMI (β = -11.653, P = .031) were correlated with lower IOP in women, but not in men (P > .10).

CONCLUSIONS

In healthy women, greater fat mass was associated with higher IOP, and greater muscle mass was associated with lower IOP after adjusting for weight and BMI. Fat and muscle influenced IOP in women independently.

Inadequacy of Body Weight-Based Recommendations for Individual Protein Intake-Lessons from Body Composition Analysis

Current body weight-based protein recommendations are ignoring the large variability in body composition, particularly lean mass (LM), which drives protein requirements. We explored and highlighted the inter-individual variability of weight versus body composition-adjusted protein intakes by secondary analysis in three cohorts of (1) 574 healthy adults (mean ± SD age: 41.4 ± 15.2 years); (2) 403 cirrhotic patients (age: 44.7 ± 12.3 years) and (3) 547 patients with lung cancer (age: 61.3 ± 8.2 years). LM was assessed using different devices (magnetic resonance imaging, dual-energy X-ray absorptiometry, computer tomography, total body potassium and bioelectrical impedance), body weight-based protein intake, its ratio (per kg LM) and mean protein requirement were calculated. Variability in protein intake in all cohorts ranged from 0.83 to 1.77 g protein per kg LM per day using (theoretical protein intake of 60 g protein per day). Calculated mean protein requirement was 1.63 g protein per kg LM per day; consequently, 95.3% of healthy subjects, 100% of cirrhotic and 97.4% of cancer patients would present with a low protein intake per kg LM. Weight-adjusted recommendations are inadequate to address the LM specific differences in protein needs of healthy subjects or clinical populations. Absolute protein intake seems to be more relevant compared to the relative proportion of protein, which in turn changes with different energy needs.

Practical Considerations for Body Composition Assessment of Adults with Class II/III Obesity Using Bioelectrical Impedance Analysis or Dual-Energy X-Ray Absorptiometry

PURPOSE OF REVIEW

The purpose of this review is to explore the practical considerations for body composition assessment of adults with class II/III obesity. Studies assessing adults (18-64 years) with a body mass index (BMI) ≥35 kg/m² with bioelectrical impedance analysis (BIA) and/or dual-energy X-ray absorptiometry (DXA) were included.

RECENT FINDINGS

Twelve studies met inclusion criteria. Five considerations were identified: variances in equipment and technology, equipment weight capacity, subject positioning, tissue penetration, and total body hydration. In subjects with BMI ≥35 kg/m², BIA overestimated fat-free mass with scaling errors as BMI increased. DXA provided accurate and reliable body composition measures, but equipment-related barriers prevented assessment of some taller, wider, and heavier subjects. BIA is an unreliable method to assess body composition in class II/III obesity. Advancements in DXA technology (e.g., iDXA), methodology (e.g., subject positioning, longer scan times), and more inclusive testing criteria (e.g., use equipment limits not just BMI) may improve access and understanding of body composition in this cohort.

Anabolic resistance does not explain sarcopenia in patients with type 2 diabetes mellitus, compared with healthy controls, despite reduced mTOR pathway activity

BACKGROUND

Ageing and type 2 diabetes mellitus (T2DM) are risk factors for skeletal muscle loss. We investigated whether anabolic resistance to feeding might underlie accelerated muscle loss in older people with T2DM and whether dysregulated mTOR signalling was implicated.

SUBJECTS

8 obese men with T2DM, and 12 age-matched controls were studied (age 68 ± 3 vs. 68±6 y; BMI: 30 ± 2 vs. 27 ± 5 kg m^-2).

METHODS

Body composition was measured by dual-X-ray absorptiometry. Insulin and glucose were clamped at post-absorptive concentrations (13 ± 2 vs. 9 ± 3 mU l^-1; 7.4 ± 1.9 vs. 4.6 ± 0.4 mmol l^-1; T2DM vs. controls). Fractional synthetic rates (FSR) of myofibrillar and sarcoplasmic proteins were measured as the rate of incorporation of [¹³C] leucine during a primed, constant infusion of [1-¹³C] α-ketoisocaproic acid, 3 h after 10 or 20 g of essential amino acids (EAA) were orally administered. Protein expression of total and phosphorylated mTOR signalling proteins was determined by Western blot analysis.

RESULTS

Despite a significantly lower appendicular lean mass index and a greater fat mass index in T2DM vs. controls, basal myofibrillar and sarcoplasmic and post-prandial myofibrillar FSR were similar. After 20 g EAA, stimulation of sarcoplasmic FSR was slightly blunted in T2DM patients. Furthermore, feeding 20 g EAA increased phosphorylation of mTOR, p70^S6k and 4E-BP1 by 60-100% in controls with no response observed in T2DM.

CONCLUSIONS

There was clear dissociation between changes in mTOR signalling versus changes in protein synthesis rates. However, the intact anabolic response of myofibrillar FSR to feeding in both groups suggests anabolic resistance may not explain accelerated muscle loss in T2DM.

Impact of Body Weight and Body Composition on Ovarian Cancer Prognosis

Measures of body weight and anthropometrics such as body mass index (BMI) are commonly used to assess nutritional status in clinical conditions including cancer. Extensive research has evaluated associations between body weight and prognosis in ovarian cancer patients, yet little is known about the potential impact of body composition (fat mass (FM) and fat-free mass (FFM)) in these patients. Thus, the purpose of this publication was to review the literature (using PubMed and EMBASE) evaluating the impact of body weight and particularly body composition on surgical complications, morbidity, chemotherapy dosing and toxicity (as predictors of prognosis), and survival in ovarian cancer patients. Body weight is rarely associated with intra-operative complications, but obesity predicts higher rates of venous thromboembolism and wound complications post-operatively in ovarian cancer patients. Low levels of FM and FFM are superior predictors of length of hospital stay compared to measures of body weight alone, but the role of body composition on other surgical morbidities is unknown. Obesity complicates chemotherapy dosing due to altered pharmacokinetics, imprecise dosing strategies, and wide variability in FM and FFM. Measurement of body composition has the potential to reduce toxicity if the results are incorporated into chemotherapy dosing calculations. Some findings suggest that excess body weight adversely affects survival, while others find no such association. Limited studies indicate that FM is a better predictor of survival than body weight in ovarian cancer patients, but the direction of this relationship has not been determined. In conclusion, body composition as an indicator of nutritional status is a better prognostic tool than body weight or BMI alone in ovarian cancer patients.

Is Obesity Associated with Altered Energy Expenditure?

Historically, obese individuals were believed to have lower energy expenditure (EE) rates than nonobese individuals (normal and overweight), which, in the long term, would contribute to a positive energy balance and subsequent weight gain. The aim of this review was to critically appraise studies that compared measures of EE and its components, resting EE (REE), activity EE (AEE), and diet-induced thermogenesis (DIT), in obese and nonobese adults to elucidate whether obesity is associated with altered EE. Contrary to popular belief, research has shown that obese individuals have higher absolute REE and total EE. When body composition (namely the metabolically active component, fat-free mass) is taken into account, these differences between obese and nonobese individuals disappear, suggesting that EE in obese individuals is not altered. However, an important question is whether AEE is lower in obese individuals because of a decrease in overall physical activity or because of less energy expended while performing physical activity. AEE and DIT could be reduced in obese individuals, mostly because of unhealthy behavior (low physical activity, higher intake of fat). However, the current evidence does not support the hypothesis that obesity is sustained by lower daily EE or REE. Future studies, comparing EE between obese and nonobese and assessing potential physiologic abnormalities in obese individuals, should be able to better answer the question of whether these individuals have altered energy metabolism.

Body composition and functional assessment of nutritional status in adults: a narrative review of imaging, impedance, strength and functional techniques

The accurate and valid assessment of body composition is essential for the diagnostic evaluation of nutritional status, identifying relevant outcome measures, and determining the effectiveness of current and future nutritional interventions. Developments in technology and our understanding of the influences of body composition on risk and outcome will provide practitioners with new opportunities to enhance current practice and to lead future improvements in practice. This is the second of a two-part narrative review that aims to critically evaluate body composition methodology in diverse adult populations, with a primary focus on its use in the assessment and monitoring of under-nutrition. Part one focused on anthropometric variables [Madden and Smith (2016) J Hum Nutr Diet 29: 7-25] and part two focuses on the use of imaging techniques, bioelectrical impedance analysis, markers of muscle strength and functional status, with particular reference to developments relevant to practice.

Fourteen days of bed rest induces a decline in satellite cell content and robust atrophy of skeletal muscle fibers in middle-aged adults

Bed rest, a ground-based spaceflight analog, induces robust atrophy of skeletal muscle, an effect that is exacerbated with increasing age. We examined the effect of 14 days of bed rest on skeletal muscle satellite cell content and fiber type atrophy in middle-aged adults, an understudied age demographic with few overt signs of muscle aging that is representative of astronauts who perform long-duration spaceflight. Muscle biopsies were obtained from the vastus lateralis of healthy middle-aged adults [n= 7 (4 male, 3 female); age: 51 ± 1 yr] before (Pre-BR) and after (Post-BR) 14 days of bed rest. Immunohistochemical analyses were used to quantify myosin heavy chain (MyHC) isoform expression, cross-sectional area (CSA), satellite cell and myonuclear content, and capillary density. Peak oxygen consumption, knee extensor strength, and body composition were also measured Pre-BR and Post-BR. Post-BR MyHC type 2a fiber percentage was reduced, and mean CSA decreased in all fiber types (-24 ± 5%;P< 0.05). Satellite cell content was also reduced Post-BR (-39 ± 9%;P< 0.05), and the change in satellite cell content was significantly correlated with the change in mean fiber CSA (r(2)= 0.60;P< 0.05). A decline in capillary density was observed Post-BR (-23 ± 6%;P< 0.05), and Post-BR capillary content was significantly associated with Post-BR peak aerobic capacity (r(2)= 0.59;P< 0.05). A subtle decline in myonuclear content occurred during bed rest (-5 ± 1%;P< 0.05). The rapid maladaptation of skeletal muscle to 14 days of mechanical unloading in middle-aged adults emphasizes the need for robust countermeasures to preserve muscle function in astronauts.

New obesity classification criteria as a tool for bariatric surgery indication

Obesity plays relevant pathophysiological role in the development of health problems, arising as result of complex interaction of genetic, nutritional, and metabolic factors. Due to the role of adipose tissue in lipid and glucose metabolism, and low grade inflammation, it is necessary to classify obesity on the basis of body fat composition and distribution, rather than the simply increase of body weight, and the Body Mass Index. The new term of adiposopathy (‘‘sick fat’’) clearly defines the pathogenic role of adipose tissue. Four phenotypes of obese individuals have been described: (1) normal weight obese (NWO); (2) metabolically obese normal weight; (3) metabolically healthy obese; and (4) metabolically unhealthy obese or “at risk” obese. Moreover, sarcopenic obesity has been related to all the phenotypes. The category of normal weight lean, represented by metabolically healthy normal weight has been classified to distinguish from NWO. It is crucial to recommend a bariatric surgery taking into account adiposopathy and sick fat that occurs with the expansion of fat mass, changing the inflammatory and metabolic profile of the patient. Body fat percentage and genetic polymorphism have to be evaluated to personalize the best bariatric surgery intervention.

Beyond BMI: Conceptual Issues Related to Overweight and Obese Patients

BMI is widely used as a measure of weight status and disease risks; it defines overweight and obesity based on statistical criteria. BMI is a score; neither is it biologically sound nor does it reflect a suitable phenotype worthwhile to study. Because of its limited value, BMI cannot provide profound insight into obesity biology and its co-morbidity. Alternative assessments of weight status include detailed phenotyping by body composition analysis (BCA). However, predicting disease risks, fat mass, and fat-free mass as assessed by validated techniques (i.e., densitometry, dual energy X ray absorptiometry, and bioelectrical impedance analysis) does not exceed the value of BMI. Going beyond BMI and descriptive BCA, the concept of functional body composition (FBC) integrates body components into regulatory systems. FBC refers to the masses of body components, organs, and tissues as well as to their inter-relationships within the context of endocrine, metabolic and immune functions. FBC can be used to define specific phenotypes of obesity, e.g. the sarcopenic-obese patient. Well-characterized obesity phenotypes are a precondition for targeted research (e.g., on the genomics of obesity) and patient-centered care (e.g., adequate treatment of individual obese phenotypes such as the sarcopenic-obese patient). FBC contributes to a future definition of overweight and obesity based on physiological criteria rather than on body weight alone.

A Second Look at the Association between Gender and Mortality on Antiretroviral Therapy

Objective

We assessed the association between gender and mortality on antiretroviral therapy (ART) using identical models with and without sex-specific categories for weight and hemoglobin.

Design

Cohort study of adult patients on ART.

Setting

GHESKIO Clinic in Port-au-Prince, Haiti.

Participants

4,717 ART-naïve adult patients consecutively enrolled on ART at GHESKIO from 2003 to 2008.

Main Outcome Measure

Mortality on ART; multivariable analyses were conducted with and without sex-specific categories for weight and hemoglobin.

Results

In Haiti, male gender was associated with mortality (OR 1.61; 95% CI: 1.30–2.00) in multivariable analyses with hemoglobin and weight included as control variables, but not when sex-specific interactions with hemoglobin and weight were used.

Conclusions

If sex-specific categories are omitted, multivariable analyses indicate a higher risk of mortality for males vs. females of the same weight and hemoglobin. However, because males have higher normal values for weight and hemoglobin, the males in this comparison would generally have poorer health status than the females. This may explain why gender differences in mortality are sometimes observed after controlling for differences in baseline variables when gender-specific interactions with weight and hemoglobin are omitted.

Application of standards and models in body composition analysis

The aim of this review is to extend present concepts of body composition and to integrate it into physiology. In vivo body composition analysis (BCA) has a sound theoretical and methodological basis. Present methods used for BCA are reliable and valid. Individual data on body components, organs and tissues are included into different models, e.g. a 2-, 3-, 4- or multi-component model. Today the so-called 4-compartment model as well as whole body MRI (or computed tomography) scans are considered as gold standards of BCA. In practice the use of the appropriate method depends on the question of interest and the accuracy needed to address it. Body composition data are descriptive and used for normative analyses (e.g. generating normal values, centiles and cut offs). Advanced models of BCA go beyond description and normative approaches. The concept of functional body composition (FBC) takes into account the relationships between individual body components, organs and tissues and related metabolic and physical functions. FBC can be further extended to the model of healthy body composition (HBC) based on horizontal (i.e. structural) and vertical (e.g. metabolism and its neuroendocrine control) relationships between individual components as well as between component and body functions using mathematical modelling with a hierarchical multi-level multi-scale approach at the software level. HBC integrates into whole body systems of cardiovascular, respiratory, hepatic and renal functions. To conclude BCA is a prerequisite for detailed phenotyping of individuals providing a sound basis for in depth biomedical research and clinical decision making.

Vitamin D status, body composition and glycemic control in an ambulatory population with diabetes and chronic kidney disease

BACKGROUND/OBJECTIVES

To determine the interrelationships between body composition, glycemic control and vitamin D status in an ambulatory population with diabetes (DM) and chronic kidney disease (CKD).

SUBJECTS/METHODS

Adult (18-80 years) patients (n=60) with DM and stage 1-4 CKD were recruited from the Northern Alberta Renal Program. Outcome variables included body composition (absolute/regional fat (FM)/lean soft tissue/total mass, percent fat/lean/fat-free (FFM) mass), glycemic control (glycated hemoglobin (HbA1c)), vitamin D intake (dietary/supplemental) and vitamin D status (25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D)) measured by validated methodologies. Sarcopenia was determined as an appendicular skeletal mass/height(2) less than 7.26 kg/m(2) (males) and 5.45 kg/m(2) (females).

RESULTS

Suboptimal HbA1c (>7%), 25(OH)D (<50 nmol/l) and 1,25(OH)2D (<43 pmol/l) concentrations were present in 57, 8 and 11% of participants. Ten percent of subjects had sarcopenia. Gender/age/DM type, not CKD, significantly influenced regional/whole body composition. Females, older participants and those with type 2 DM had higher %FM. No significant interrelationships between vitamin D status and glycemic control were observed (P>0.05). Serum 25(OH)D concentrations were inversely associated with arm lean soft tissue/FFM/total mass, weight, appendicular skeletal mass, lean soft tissue/height(2), FFM/height(2), appendicular skeletal mass/height(2) and body mass index (P<0.05). Sarcopenia occurred more frequently in patients with 25(OH)D concentrations ⩾100 nmol/l. Regional/whole body %FM was inversely related to 1,25(OH)2D, not 25(OH)D.

CONCLUSIONS

Body composition, not glycemic control, is associated with vitamin D status in an ambulatory population of adults with DM and CKD.