DXA reference values and anthropometric screening for visceral obesity in Western Australian adults.Sci Rep. 2020;10:18731. [PMID: 33127940 DOI: 10.1038/s41598-020-73631-x]

Longitudinal associations of DXA-measured visceral adipose tissue and cardiometabolic risk in middle-to-older aged adults

BACKGROUND AND AIMS

DXA-measured visceral adipose tissue (VATDXA) is associated with adverse cardiometabolic risk profiles in cross-sectional studies, but longitudinal associations have not been investigated. We examined the longitudinal associations of baseline and change in VATDXA with future cardiometabolic risk in Australian participants of the Busselton Healthy Ageing study.

METHODS AND RESULTS

We studied 3569 participants (54.7% female, aged 46-70 years) with data on VATDXA (GE Lunar Prodigy) and cardiometabolic risk factors at baseline and 6 years follow-up. The associations were examined using logistic and linear regression models, adjusting for baseline age and lifestyle factors. Mean baseline VATDXA mass was 1653 ± 880 g and 855 ± 580 g, and mean change in VATDXA +99 ± 500 g and +58 ± 312 g in males and females, respectively. Among all participants, 182 males (11.3%) and 197 females (10.1%) developed incident metabolic syndrome (MetS). Baseline VATDXA was associated with incident MetS with an adjusted odds ratio of 2.53 (95% CI: 2.03, 3.15) in males and 2.78 (2.30, 3.36) in females per SD increment. There was a graded positive association between longitudinal change in VATDXA and MetS severity z score in both sexes adjusted for baseline VAT (P < 0.001). All the above associations remained significant after further adjustment for baseline or change in BMI, waist circumference or waist-to-hip ratio in respective models (all P < 0.001).

CONCLUSIONS

Higher baseline and greater longitudinal increase in VATDXA are independently associated with raised cardiometabolic risk over time, and may serve as useful markers for identifying middle-aged individuals at increased cardiometabolic risk.

The ASSIST trial: Acute effects of manipulating strength exercise volume on insulin sensitivity in obese adults: A protocol for a randomized controlled, crossover, clinical trial

Type 2 diabetes mellitus is a disease in which insulin action is impaired, and an acute bout of strength exercise can improve insulin sensitivity. Current guidelines for strength exercise prescription suggest that 8 to 30 sets could be performed, although it is not known how variations in exercise volume impact insulin sensitivity. Additionally, this means an almost 4-fold difference in time commitment, which might directly impact an individual's motivation and perceived capacity to exercise. This study will assess the acute effects of high- and low-volume strength exercise sessions on insulin sensitivity. After being thoroughly familiarized, 14 obese individuals of both sexes (>40 year old) will undergo 3 random experimental sessions, with a minimum 4-day washout period between them: a high-volume session (7 exercises, 3 sets per exercise, 21 total sets); a low-volume session (7 exercises, 1 set per exercise, 7 total sets); and a control session, where no exercise will be performed. Psychological assessments (feeling, enjoyment, and self-efficacy) will be performed after the sessions. All sessions will be held at night, and the next morning, an oral glucose tolerance test will be performed in a local laboratory, from which indexes of insulin sensitivity will be derived. We believe this study will aid in strength exercise prescription for individuals who claim not to have time to exercise or who perceive high-volume strength exercise intimidating to adhere to. This trial was prospectively registered (ReBEC #RBR-3vj5dc5 https://ensaiosclinicos.gov.br/rg/RBR-3vj5dc5).

The pathophysiology of visceral adipose tissues in cardiometabolic diseases

Central pattern of fat distribution, especially fat accumulation within the intraabdominal cavity increases risks for cardiometabolic diseases. Portal hypothesis combined with a pathological remodeling in visceral fat is considered the major etiological factor explaining the independent contribution of visceral obesity to cardiometabolic diseases. Excessive remodeling in visceral fat during development of obesity leads to dysfunctions in the depot, characterized by hypertrophy and death of adipocytes, hypoxia, inflammation, and fibrosis. Dysfunctional visceral fat secretes elevated levels of fatty acids, glycerol, and proinflammatory and profibrotic cytokines into the portal vein directly impacting the liver, the central regulator of systemic metabolism. These metabolic and endocrine products induce ectopic fat accumulation, insulin resistance, inflammation, and fibrosis in the liver, which in turn causes or exacerbates systemic metabolic derangements. Elucidation of underlying mechanisms that lead to the pathological remodeling and higher degree of dysfunctions in visceral adipose tissue is therefore, critical for the development of therapeutics to prevent deleterious sequelae in obesity. We review depot differences in metabolic and endocrine properties and expendabilities as well as underlying mechanisms that contribute to the pathophysiological aspects of visceral adiposity in cardiometabolic diseases. We also discuss impacts of different weight loss interventions on visceral adiposity and cardiometabolic diseases.

Visceral adipose tissue reference data computed for GE HealthCare DXA from the National Health and Nutrition Examination Survey data set

OBJECTIVE

The National Health and Nutrition Examination Survey (NHANES) characterizes body composition representative of the US population using dual-energy x-ray absorptiometry (DXA) scans. These population-level trends of abdominal subcutaneous and visceral adipose tissue (SAT and VAT) are useful for identifying measures associated with increased disease risk. Recently, VAT and SAT data collected by Hologic DXA in NHANES were published online; however, there are known differences in the absolute calibration of DXA systems by make. The purpose of this study was to create reference tables suitable for calculating z scores and percentile values for GE HealthCare (GEHC) DXA systems.

METHODS

DXA scans were acquired on participants aged 8 to 59 years using Hologic systems. DXA measures were converted to GEHC and described using the least median squares curve fitting method in pediatrics (aged <20 years) and adults (aged 20-59 years).

RESULTS

A total of 11,972 adults and 7298 pediatrics were included for this analysis. Adult and pediatric curves were generated by sex and by ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic, Asian, Other) and were derived as a function of age.

CONCLUSIONS

These results show the ability to generate VAT and SAT reference data for GEHC systems using Hologic DXA data representative of the US youth and adult population.

Longitudinal concordance of body composition and anthropometric assessment by a novel smartphone application across a 12-week self-managed weight loss intervention

Smartphone applications (SPA) now offer the ability to provide accessible in-home monitoring of relevant individual health biomarkers. Previous cross-sectional validations of similar technologies have reported acceptable accuracy with high-grade body composition assessments; this research assessed longitudinal agreement of a novel SPA across a self-managed weight loss intervention of thirty-eight participants (twenty-one males, seventeen females). Estimations of body mass (BM), body fat percentage (BF%), fat-free mass (FFM) and waist circumference (WC) from the SPA were compared with ground truth (GT) measures from a dual-energy X-ray absorptiometry scanner and expert technician measurement. Small mean differences (MD) and standard error of estimate (SEE) were observed between method deltas (ΔBM: MD = 0·12 kg, SEE = 2·82 kg; ΔBF%: MD = 0·06 %, SEE = 1·65 %; ΔFFM: MD = 0·17 kg, SEE = 1·65 kg; ΔWC: MD = 1·16 cm, SEE = 2·52 cm). Concordance correlation coefficient (CCC) assessed longitudinal agreement between the SPA and GT methods, with moderate concordance (CCC: 0·55-0·73) observed for all measures. The novel SPA may not be interchangeable with high-accuracy medical scanning methods yet offers significant benefits in cost, accessibility and user comfort, in conjunction with the ability to monitor body shape and composition estimates over time.

Assessment of correlation between conventional anthropometric and imaging-derived measures of body fat composition: a systematic literature review and meta-analysis of observational studies

BACKGROUND

In studies of the association of adiposity with disease risk, widely used anthropometric measures of adiposity (e.g. body-mass-index [BMI], waist circumference [WC], waist-hip ratio [WHR]) are simple and inexpensive to implement at scale. In contrast, imaging-based techniques (e.g. magnetic resonance imaging [MRI] and dual x-ray absorptiometry [DXA]) are expensive and labour intensive, but can provide more accurate quantification of body fat composition. There is, however, limited evidence about the relationship between conventional and imaging-derived measures of adiposity.

METHODS

We searched Scopus and Web of Science for published reports in English of conventional versus imaging-derived measurements of adiposity. We identified 42 articles (MRI = 22; DXA = 20) that met selection criteria, involving 42,556 (MRI = 15,130; DXA = 27,426) individuals recruited from community or hospital settings. Study-specific correlation coefficients (r) were transformed using Fisher's Z transformation, and meta-analysed to yield weighted average correlations, both overall and by ancestry, sex and age, where feasible. Publication bias was investigated using funnel plots and Egger's test.

RESULTS

Overall, 98% of participants were 18 + years old, 85% male and 95% White. BMI and WC were most strongly correlated with imaging-derived total abdominal (MRI-derived: r = 0.88-; DXA-derived: 0.50-0.86) and subcutaneous abdominal fat (MRI-derived: 0.83-0.85), but were less strongly correlated with visceral abdominal fat (MRI-derived: 0.76-0.79; DXA-derived: 0.80) and with DXA-derived %body fat (0.76). WHR was, at best, strongly correlated with imaging-derived total abdominal (MRI-derived: 0.60; DXA-derived: 0.13), and visceral abdominal fat (MRI-derived: 0.67; DXA-derived: 0.65), and moderately with subcutaneous abdominal (MRI-derived: 0.54), and with DXA-derived %body fat (0.58). All conventional adiposity measures were at best moderately correlated with hepatic fat (MRI-derived: 0.36-0.43). In general, correlations were stronger in women than in men, in Whites than in non-Whites, and in those aged 18 + years.

CONCLUSIONS

In this meta-analysis, BMI and WC, but not WHR, were very strongly correlated with imaging-derived total and subcutaneous abdominal fat. By comparison, all three measures were moderately or strongly correlated with imaging-based visceral abdominal fat, with WC showing the greatest correlation. No anthropometric measure was substantially correlated with hepatic fat. Further larger studies are needed to compare these measures within the same study population, and to assess their relevance for disease risks in diverse populations.

Sex-specific equations to estimate body composition: Derivation and validation of diagnostic prediction models using UK Biobank

BACKGROUND & AIMS

Body mass index and waist circumference are simple measures of obesity. However, they do not distinguish between visceral and subcutaneous fat, or muscle, potentially leading to biased relationships between individual body composition parameters and adverse health outcomes. The purpose of this study was to develop and validate prediction models for volumetric adipose and muscle.

METHODS

Based on cross-sectional data of 18,457, 18,260, and 17,052 White adults from the UK Biobank, we developed sex-specific equations to estimate visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (ASAT), and total thigh fat-free muscle (FFM) volumes, respectively. Volumetric magnetic resonance imaging served as the reference. We used the least absolute shrinkage and selection operator and the extreme gradient boosting methods separately to fit three sequential models, the inputs of which included demographics and anthropometrics and, in some, bioelectrical impedance analysis parameters. We applied comprehensive metrics to assess model performance in the temporal validation set.

RESULTS

The equations that included more predictors generally performed better. Accuracy of the equations was moderate for VAT (percentage of estimates that differed <30% from the measured values, 70 to 78 in males, 64 to 69 in females) and good for ASAT (85 to 91 in males, 90 to 95 in females) and FFM (99 to 100 in both sexes). All the equations appeared precise (interquartile range of the difference, 0.89 to 1.76 L for VAT, 1.16 to 1.61 L for ASAT, 0.81 to 1.39 L for FFM). Bias of all the equations was negligible (-0.17 to 0.05 L for VAT, -0.10 to 0.12 L for ASAT, -0.07 to 0.09 L for FFM). The equations achieved superior cardiometabolic correlations compared with body mass index and waist circumference.

CONCLUSIONS

The developed equations to estimate VAT, ASAT, and FFM volumes achieved moderate to good performance. They may be cost-effective tools to revisit the implications of diverse body components.

Abdominal obesity in COPD is associated with specific metabolic and functional phenotypes

BACKGROUND

Abdominal obesity (AO) is linked to reduced health status and mortality. While it is known that AO is prevalent in chronic obstructive pulmonary disease (AO-COPD), the specific metabolic and functional consequences associated with AO-COPD remain understudied.

METHODS

We studied 199 older adults with COPD and 168 control subjects with and without AO and assessed visceral adipose tissue (VAT) by dual-energy X-ray absorptiometry. VAT > 70th percentile of the control group qualified a subject as AO in a sex specific manner. We measured plasma concentrations and whole body production (WBP) rates of multiple amino acids to assess the metabolic profile. We assessed medical history, body composition by Dual-Energy X-ray Absorptiometry, muscle strength, and cognitive function. We performed statistics by analysis of covariance (p) and FDR (q) for multiple comparisons.

RESULTS

AO-COPD subjects had 27% more VAT (q < 0.01) than AO-Control subjects despite correction for BMI. Branched-chain amino acid concentrations and WBP rates were generally elevated in AO-COPD but whole body clearance rate was only elevated in COPD. Metabolic syndrome comorbidities (p < 0.01) and systemic inflammation (P < 0.05) were most prevalent in the AO-COPD group. Muscle strength was reduced in COPD subjects (p < 0.001), but partially preserved when combined with AO. Cognitive dysfunction and mood disturbances were present in COPD subjects (p < 0.001) with worst performers in AO-COPD (q < 0.05).

CONCLUSION

The presence of AO is associated with specific metabolic and functional phenotypes in COPD. Clinical trial registry Trial registration ClinicalTrials.gov. In the present paper, we report an analysis of the baseline measurements of COPD subjects and healthy controls from the study numbers: NCT01787682, NCT01787682, NCT02157844, NCT02082418, NCT02065141, NCT02770092, NCT02908425, NCT03159390, NCT02780219, NCT03327181, NCT03796455, NCT04928872, NCT04461236, NCT01173354, NCT01154400.

Development and Validation of Waist Girth-Based Equations to Evaluate Body Composition in Colombian Adults: Rationale and STROBE-Nut-Based Protocol of the F20 Project

Waist girth (WG) represents a quick, simple, and inexpensive tool that correlates with excess of fat mass in humans; however, this measurement does not provide information on body composition. The evaluation of body composition is one of the main components in the assessment of nutritional status. Indeed, the use of anthropometry-based equations to estimate body fat and fat-free mass is a frequent strategy. Considering the lack of validation in the Colombian population, the aim of this research study (the F20 Project) is to externally validate WG-based equations (e.g., relative fat mass), and also to develop and validate new models that include WG to estimate body composition in Colombian adults compared to DXA. This cross-sectional study will be carried out following the guidelines for Strengthening the Reporting of Observational Studies in Epidemiology-Nutritional Epidemiology (STROBE-nut). Using stratified probabilistic sampling, the study population will be adults with different levels of physical activity residing in Medellín and its metropolitan area. The results of this study will not only validate the estimation performance of the current WG-based equations, but they will also develop new equations to estimate body composition in the Colombian population. This will improve professional practice in health, exercise, and sports sciences (ClinicalTrials.gov ID #NCT05450588).

DXA-Derived vs Standard Anthropometric Measures for Predicting Cardiometabolic Risk in Middle-Aged Australian Men and Women

It is not clear if dual-energy X-ray absorptiometry (DXA) adiposity measures are superior to standard anthropometric measures for predicting cardiometabolic (CM) risk factors in a middle-aged general population. In the Busselton Healthy Ageing Study, we assessed a range of standard anthropometric and DXA-derived adiposity measures to predict metabolic syndrome (MetS) and CM risk factors in 4831 "baby boomers" aged 45-69 yr. Anthropometric and whole body DXA (GE Lunar Prodigy) measures were collected. Cross-sectional relationships of overall adiposity (BMI; DXA fat mass index, body fat %), central adiposity (waist circumference (WC); DXA trunk fat, android fat, abdominal visceral adipose tissue (VAT)) and ratio index (waist-to-hip ratio; DXA trunk/legs fat, android/gynoid ratio, VAT/total fat) with MetS and its components (as both continuous and binary outcomes) were evaluated using linear and logistic regression adjusting for age and lifestyle factors. Youden's Index was used to determine the optimal cut-points for predicting MetS. In linear regression analyses, central adiposity measures showed stronger associations with MetS score and CM risk factors than overall adiposity measures and fat ratio index, and DXA-VAT provided stronger associations than WC. Logistic regression models showed similar findings. For MetS diagnosis present in 35.9% of males and 24.4% of females, the highest odds ratio (95% CI) per SD change was observed for DXA-VAT (males: 5.02 [4.28, 5.88]; females: 3.91 [3.40, 4.49]), which remained significant (all p < 0.001) after further adjustment for BMI (males: 3.27 [2.65, 4.02]; females: 3.37 [2.79, 4.06]) or WC (males: 2.46 [1.95, 3.10]; females: 2.75 [2.21, 3.43]). The optimal DXA-VAT mass cut-point for predicting MetS was 1608 grams in males and 893 grams in females. DXA-VAT was superior to standard anthropometric and other DXA-derived adiposity measures for prediction of cardiometabolic risk factors, and has clinical utility for identifying middle-aged individuals at increased risk of MetS.

Correlations between percent body fat measured by dual-energy X-ray absorptiometry and anthropometric measurements in Thai persons with chronic traumatic spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To determine and compare the correlations of percent body fat (%BF) evaluated by dual-energy X-ray absorptiometry (DEXA) and anthropometric measurements including body mass index (BMI), skinfold thickness, waist circumference, hip circumference, and waist to hip ratio in Thai persons with chronic traumatic spinal cord injury (SCI).

SETTING

An SCI-specialized rehabilitation facility in a university hospital.

METHODS

Forty-six Thais with chronic traumatic SCI from a chronic SCI cohort of Maharaj Nakorn Chiang Mai Hospital were enrolled. Anthropometric measurements including weight, height, BMI, waist circumference, hip circumference, waist to hip ratio, and skinfold thickness of four sites (biceps, triceps, subscapular, and suprailiac) were measured. The estimated %BF was calculated using the Durnin-Womersley formula based on the sum of 4-site skinfold thickness. Data of %BF was evaluated by DEXA within 3 months before anthropometric measurements of each participant were obtained. The correlations between each anthropometric parameter and % BF from DEXA were determined by the Pearson correlation coefficient.

RESULTS

The correlation of %BF between two methods, i.e., DEXA and estimation based on 4-site skinfold thickness, was strongly positive (r = 0.829; p < 0.001). The correlations between %BF from DEXA and hip circumference, BMI, and waist circumference were moderately positive (r = 0.697, 0.540, and 0.540, respectively; all p < 0.001).

CONCLUSION

Better than the other anthropometric measurements, the estimation of %BF based on the 4-site skinfold using the Durnin-Womersley formula is a practical method for evaluating obesity in Thai people with chronic traumatic SCI.

Associations of the Cardiometabolic Index with the Risk of Cardiovascular Disease in Patients with Hypertension and Obstructive Sleep Apnea: Results of a Longitudinal Cohort Study

Purpose

We aimed to explore the relationship between the cardiometabolic index (CMI) and cardiovascular disease (CVD) and its subtypes (coronary artery disease and stroke) in patients with hypertension and obstructive sleep apnea (OSA).

Methods

We conducted a retrospective cohort study enrolling 2067 participants from the Urumqi Research on Sleep Apnea and Hypertension study. The CMI was calculated as triglyceride to high‐density lipoprotein cholesterol ratio × waist‐to‐height ratio. Participants were divided into three groups (T1, T2, and T3) according to the tertile of CMI. The Kaplan-Meier method helped to calculate the cumulative incidence of CVD in different groups. We assessed the association of CMI with the risk of CVD and CVD subtypes by estimating hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox models.

Results

During a median follow-up of 6.83 years (interquartile range: 5.92-8.00 years), 326 incident CVD were identified, including 121 incident stroke and 205 incident coronary heart disease (CHD). Overall, after adjusting for confounding variables, CMI was positively associated with the risk of new-onset CVD (per SD increment, adjusted HR: 1.31; 95% CI: 1.20, 1.43), new-onset CHD (per SD increment, adjusted HR: 1.33; 95% CI: 1.20, 1.48), and new-onset stroke (per SD increment, adjusted HR: 1.27; 95% CI: 1.10, 1.47). Similar results were obtained in various subgroup and sensitivity analyses. Adding CMI to the baseline risk model for CVD improved the C-index (P < 0.001), continuous net reclassification improvement (P < 0.001), and integrated discrimination index (P < 0.001). Similar results were observed for CHD and stroke.

Conclusion

There was a positive association between CMI levels and the risk of new-onset CVD in patients with hypertension and OSA. This finding suggests that CMI may help identify people at high risk of developing CVD.

Equations for predicting DXA-measured visceral adipose tissue mass based on BMI or weight in adults

Background

Obesity, especially presenting with excessive amounts of visceral adipose tissue (VAT), is strongly associated with insulin resistance (IR), atherosclerosis, metabolic syndrome, and cardiovascular diseases (CVDs).

Aims

To construct a predication equation for estimating VAT mass using anthropometric parameters and validate the models with a validation group.

Methods

Five hundred fifteen subjects (366 for the derivation group and 149 for the validation group) were enrolled in the study. The anthropometric parameters, blood lipid profile, and VAT mass were accessed from medical records. Stepwise regression was applied to develop prediction models based on the dual X–ray absorptiometry (DXA)-measured VAT mass in the derivation group. Bland–Altman plots and correlation analysis were performed to validate the agreements in the validation group. The performance of the prediction equations was evaluated with the Hosmer–Lemeshow test and area under the curve (AUC).

Results

Model 1, which included age, sex, body mass index (BMI), triglyceride (TG), high-density lipoprotein (HDL), and the grade of hepatic steatosis, had a variance of 70%, and model 2, which included age, sex, weight, height, TG, HDL, and the grade of hepatic steatosis, had a variance of 74%. The VAT mass measured by DXA was correlated with age, sex, height, weight, BMI, TG, HDL, and grade of hepatic steatosis. In the validation group, the VAT mass calculated by the prediction equations was strongly correlated with the DXA–VAT mass (r = 0.870, r = 0.875, respectively). The AUC, sensitivity, and specificity of the two prediction equations were not significantly different (both P = 0.933).

Conclusion

The study suggests that prediction equations including age, sex, height, BMI, weight, TG, HDL, and the grade of hepatic steatosis could be useful tools for predicting VAT mass when DXA is not available.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01652-8.

Role of Obesity, Physical Exercise, Adipose Tissue-Skeletal Muscle Crosstalk and Molecular Advances in Barrett's Esophagus and Esophageal Adenocarcinoma

Both obesity and esophageal adenocarcinoma (EAC) rates have increased sharply in the United States and Western Europe in recent years. EAC is a classic example of obesity-related cancer where the risk of EAC increases with increasing body mass index. Pathologically altered visceral fat in obesity appears to play a key role in this process. Visceral obesity may promote EAC by directly affecting gastroesophageal reflux disease and Barrett’s esophagus (BE), as well as a less reflux-dependent effect, including the release of pro-inflammatory adipokines and insulin resistance. Deregulation of adipokine production, such as the shift to an increased amount of leptin relative to “protective” adiponectin, has been implicated in the pathogenesis of BE and EAC. This review discusses not only the epidemiology and pathophysiology of obesity in BE and EAC, but also molecular alterations at the level of mRNA and proteins associated with these esophageal pathologies and the potential role of adipokines and myokines in these disorders. Particular attention is given to discussing the possible crosstalk of adipokines and myokines during exercise. It is concluded that lifestyle interventions to increase regular physical activity could be helpful as a promising strategy for preventing the development of BE and EAC.

Differences in the choroid plexus volume and microstructure are associated with body adiposity

The choroid plexus (CP) is a cerebral structure located in the ventricles that functions in producing most of the brain's cerebrospinal fluid (CSF) and transporting proteins and immune cells. Alterations in CP structure and function has been implicated in several pathologies including aging, multiple sclerosis, Alzheimer's disease, and stroke. However, identification of changes in the CP remains poorly characterized in obesity, one of the main risk factors of neurodegeneration, including in the absence of frank central nervous system alterations. Our goal here was to characterize the association between obesity, measured by the body mass index (BMI) or waist circumference (WC) metrics, and CP microstructure and volume, assessed using advanced magnetic resonance imaging (MRI) methodology. This cross-sectional study was performed in the clinical unit of the National Institute on Aging and included a participant population of 123 cognitively unimpaired individuals spanning the age range of 22 - 94 years. Automated segmentation methods from FreeSurfer were used to identify the CP structure. Our analysis included volumetric measurements, quantitative relaxometry measures (T ₁ and T ₂), and the diffusion tensor imaging (DTI) measure of mean diffusivity (MD). Strong positive associations were observed between WC and all MRI metrics, as well as CP volume. When comparing groups based on the established cutoff point by the National Institutes of Health for WC, a modest difference in MD and a significant difference in T ₁ values were observed between obese and lean individuals. We also found differences in T1 and MD between obese and overweight individuals as defined using the BMI cutoff. We conjecture that these observations in CP volume and microstructure are due to obesity-induced inflammation, diet, or, very likely, dysregulations in leptin binding and transport. These findings demonstrate that obesity is strongly associated with a decline in CP microstructural integrity. We expect that this work will lay the foundation for further investigations on obesity-induced alterations in CP structure and function.

Machine learning models for predicting non-alcoholic fatty liver disease in the general United States population: NHANES database

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, affecting over 30% of the United States population. Early patient identification using a simple method is highly desirable.

AIM

To create machine learning models for predicting NAFLD in the general United States population.

METHODS

Using the NHANES 1988-1994. Thirty NAFLD-related factors were included. The dataset was divided into the training (70%) and testing (30%) datasets. Twenty-four machine learning algorithms were applied to the training dataset. The best-performing models and another interpretable model (i.e., coarse trees) were tested using the testing dataset.

RESULTS

There were 3235 participants (n = 3235) that met the inclusion criteria. In the training phase, the ensemble of random undersampling (RUS) boosted trees had the highest F1 (0.53). In the testing phase, we compared selective machine learning models and NAFLD indices. Based on F1, the ensemble of RUS boosted trees remained the top performer (accuracy 71.1% and F1 0.56) followed by the fatty liver index (accuracy 68.8% and F1 0.52). A simple model (coarse trees) had an accuracy of 74.9% and an F1 of 0.33.

CONCLUSION

Not every machine learning model is complex. Using a simpler model such as coarse trees, we can create an interpretable model for predicting NAFLD with only two predictors: fasting C-peptide and waist circumference. Although the simpler model does not have the best performance, its simplicity is useful in clinical practice.

Effects of Lifestyle Intervention on Inflammatory Markers and Waist Circumference in Overweight/Obese Adults With Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Physical inactivity and an imbalanced diet could lead to some cardio metabolic risk factors.

OBJECTIVE

The objective of this meta-analysis was to investigate the effects of lifestyle modification on inflammatory indicators and waist circumference (WC) in overweight/obese subjects with metabolic syndrome (MS).

DATA SOURCES

A systematic search was conducted in PubMed, CINAHL, MEDLINE, Cochrane, Google Scholar, and Web of Science.

STUDY SELECTION

The selection criteria were randomized controlled trials (RCTs) investigating the effects of lifestyle interventions on inflammation and WC from inception to 20 December 2020. The weighted mean difference (WMD) and 95% confidence interval (CI) between interventions were computed using a random or fixed-effects model.

RESULTS

Six RCTs (including 1246 MS patients who had, on average, overweight/obesity) met all inclusion criteria. Interventions lasted 6 to 12 months (2-5 sessions per week). Lifestyle intervention significantly reduced C-reactive protein (WMD: -0.52 mg/ml, 95% CI: -0.72, -0.33), IL-6 (WMD: -0.50 pg/ml, 95% CI: -0.56, -0.45), and increased adiponectin (WMD: 0.81 µg/ml, 95% CI, 0.64, 0.98). Moreover, lifestyle modification significantly decreased WC (WMD: -3.12 cm, 95% CI, -4.61, -1.62).

CONCLUSION

Our findings provide evidence that lifestyle alterations, including physical activity and diet, can lead to significant improvement in abdominal obesity, measured by WC and some inflammation markers among overweight/obese individuals with MS. Further high-quality research is needed to clarify the mechanisms underlying the effect of such interventions on this population's inflammatory markers.

Adults with Crohn's disease exhibit elevated gynoid fat and reduced android fat irrespective of disease relapse or remission

Crohn’s disease (CD) is a debilitating inflammatory bowel condition of unknown aetiology that is growing in prevalence globally. Large-scale studies have determined associations between female obesity or low body mass index (BMI) with risk of CD at all ages or 8– < 40 years, respectively. For males, low BMI entering adult life is associated with increased incidence of CD or ulcerative colitis up to 40 years later. Body composition analysis has shown that combinations of lean tissue loss and high visceral fat predict poor CD outcomes. Here, we assessed dietary intake, physical activity and whole or regional body composition of patients with CD relapse or remission. This anthropometric approach found people with CD, irrespective of relapse or remission, differed from a large representative healthy population sample in exhibiting elevated gynoid fat and reduced android fat. CD is associated with mesenteric adipose tissue, or “creeping fat”, that envelops affected intestine exclusive of other tissue; that fat is localised to the android region of the body. In this context, CD mesenteric adiposity represents a stark juxtaposition of organ-specific and regional adiposity. Although our study population was relatively small, we suggest tentatively that there is a rationale to refer to Crohn’s disease as a fatty intestine condition, akin to fatty liver conditions. We suggest that our data provide early insight into a subject that potentially warrants further investigation across a larger patient cohort.