Comparison of DXA and water measurements of body fat following gastric bypass surgery and a physiological model of body water, fat, and muscle composition

Body composition assessment in adult females with anorexia nervosa and bulimia nervosa - a cross-sectional study comparing dual-energy X-ray absorptiometry scan and isotopic dilution of deuterium

BACKGROUND

Eating disorders (EDs) compromise individuals' nutritional status, affecting among other organs and systems, bone health.

OBJECTIVE

This study aimed to assess and compare bone mineral density (BMD) from dual-energy x-ray absorptiometry (DXA) scan and deuterium (D₂O) dilution of adult females with anorexia nervosa (AN) and bulimia nervosa (BN).

METHODS

This was a cross-sectional study with 53 female participants (18-49 years) with a diagnosis of AN (N = 25) or BN (N = 28). DXA scan was performed to assess BMD, fat mass, and fat-free mass, and D₂O dilution was used to assess total body water (TBW), fat mass, and fat-free mass. Interviews/questionnaires were used to assess symptoms, illness trajectory, and physical activity. T-test, Chi-squared test, Pearson's linear correlation, linear regressions, and Bland-Altman analyses were performed, with a significance level of 5%.

RESULTS

TBW below the recommended level for adult females (≥ 45%) was more frequent in BN (60%) compared with AN (21%; P = 0.013). FMI (soft tissue only) (t-test P = 0.06), and FFMI (t-test P = 0.08) agreed between DXA scan and D₂O dilution. Only FFMI did not show systematic bias of proportion (β:-0.2, P = 0.177). The diagnosis of BN, binge-eating episodes, and physical activity in AN were associated with the differences in the methods' results. FMI was positively associated with BMD in AN, and both FMI and FFMI were positively associated with BMD in BN.

CONCLUSION

In adult females with EDs, DXA scan and D₂O dilution achieved agreement for FMI and FFMI. Changes in fat mass and fat-free mass are important in understanding the mechanisms behind bone loss in EDs. Protocols for body composition assessment in EDs can help to minimize the effect of the ED diagnosis, ED behaviors (i.e., excessive exercise and purging behaviors) and weight on the accuracy of measurements.

Accuracy in body composition scanning by adult half-body DXA scanning

INTRODUCTION

dual-energy X-ray absorptiometry (DXA) is the gold standard method, although one limitation is the size of the scan area.

OBJECTIVE

the objective was to verify the accuracy of body composition (BC) scanning through half-body DXA scanning compared to standard total body scanning.

METHODS

a study was conducted on 145 volunteers. Weight and height were assessed. Body mass index (BMI) was calculated. DXA was used for whole-body scan (WBS) and half-body scan (HBS). WBS was used as the reference method and the following indicators were extracted: bone mineral content (BMC), fat mass (FM), lean soft tissue (LST) and percentage fat mass (%FM).

RESULTS

no differences were observed in the body composition indicators (BMC, FM, LST and %FM) when compared between the reference WBS scanner and the HBS scanner. The predictive power between both scans ranged in both sexes between R2 = 0.94 and 0.98. The DRI desirable reproducibility index values defining the degree of agreement between both scans ranged from 0.97 to 0.99, and the values for precision (0.97 to 0.99) and accuracy (0.99) were high.

CONCLUSION

HBS scanning by DXA evidenced agreement, and high values of accuracy and precision to assess body composition indicators (BMC, FM, LST and %FM).

Evaluation of bone density and skeletal muscle mass after sleeve gastrectomy using computed tomography method

Introduction

Sleeve gastrectomy is the most common surgical procedure to reduce weight and treat metabolic complications in patients with moderate-to-severe obesity; however, it affects the musculoskeletal system. Dual-energy X-ray absorptiometry (DXA), which is commonly used to measure bone mineral density (BMD), may be affected by excess fat tissue around the bones, interrupting BMD measurement. Due to the strong correlation between DXA and the Hounsfield units (HU) obtained from computed tomography (CT) scans, BMD assessment using clinical abdominal CT scans has been useful. To date, there has been no report of detailed CT evaluation in patients with severe obesity after sleeve gastrectomy.

Objective

This study investigated the effect of sleeve gastrectomy in severely obese patients on bone and psoas muscle density, and cross-sectional area using retrospective clinical CT scans.

Methods

This was a retrospective observational study that included 86 patients (35 males and 51 females) who underwent sleeve gastrectomy between March 2012 and May 2019. Patients' clinical data (age at the time of surgery, sex, body weight, body mass index (BMI), comorbidities, and preoperative and postoperative blood test results, HU of the lumbar spine and psoas muscle and psoas muscle mass index (PMI)) were evaluated.

Results

The mean age at the time of surgery was 43 years, and the body weight and BMI significantly reduced (p < 0.01) after surgery. The mean hemoglobin A1c level showed significant improvement in males and females. Serum calcium and phosphorus levels remained unchanged before and after surgery. In CT analysis, HU of the lumbar spine and psoas muscle showed no significant decrease, but PMI showed a significant decrease (p < 0.01).

Conclusions

Sleeve gastrectomy could dramatically improve anthropometric measures without causing changes in serum calcium and phosphorus levels. Preoperative and postoperative abdominal CT revealed no significant difference in the bone and psoas muscle density, and the psoas muscle mass was significantly decreased after sleeve gastrectomy.

Phase angle (PhA) in overweight and obesity: evidence of applicability from diagnosis to weight changes in obesity treatment

Phase angle (PhA) is a recently proposed marker of nutritional status in many clinical conditions. Its use in patients with obesity presents different critical concerns due to the higher variability of the two measured parameters (resistance, R, and reactance, Xc) that contribute to the determination of PhA. Controversial is the relation between PhA and BMI that might vary with graded levels of obesity due to the variation in fat and free fat mass. Obesity is frequently associated with metabolic, hepatic, cardiovascular and kidney diseases that introduce variations in PhA values, in relation to multimorbidity and severity degree of these diseases. It is reported that the improvement of clinical condition is associated with a positive change in PhA. Also, the treatment of obesity with weight loss might confirm this effect, but with different responses in relation to the type and duration of the intervention applied. In fact, the effect appears not only related to the percentage of weight loss but also the possible loss of free fat mass and the nutritional, metabolic and structural modifications that might follow each therapeutic approach to decrease body weight. We can conclude that the PhA could be used as marker of health status in patients with obesity supporting an appropriate weight loss intervention to monitor efficacy and fat free mass preservation.

Body Composition Differences Between Excess Weight Loss ≥ 50% and < 50% at 12 Months Following Bariatric Surgery

Background

The relationship between weight loss and body composition is undefined after bariatric surgery. The objective of this study was to compare body composition changes in patients with excess weight loss ≥ 50% (EWL ≥ 50) and < 50% at 12 months post-operatively (EWL < 50).

Methods

A prospective cohort study was completed on patients undergoing bariatric surgery at two tertiary hospitals between 2017 and 2021. Body composition was measured with dual-energy X-ray absorptiometry immediately before surgery, and at 1, 6, and 12 months post-operatively. Body mass index (BMI), fat mass (FM), lean body mass (LBM), and skeletal muscle index (SMI) trajectories were analysed between patients with EWL ≥ 50% and EWL < 50%.

Results

Thirty-seven patients were included in this series (EWL ≥ 50% n = 25, EWL < 50% n = 12), comprising of both primary and revisional bariatric surgery cases, undergoing a sleeve gastrectomy (62.2%), Roux-en-Y gastric bypass (32.4%), or one anastomosis gastric bypass (5.4%). The EWL ≥ 50% group demonstrated a more optimal mean FM-to-LBM loss ratio than the EWL < 50% group. EWL ≥ 50% patients lost 2.0 kg more FM than EWL < 50% patients for each 1 kg of LBM lost. EWL ≥ 50% was also associated with an increase in mean SMI% over 12 months (5.5 vs. 2.4%; p < 0.0009). Across the whole cohort, the first month after surgery accounted for 67.4% of the total LBM reduction that occurred during the 12-month post-operative period.

Conclusion

This data suggests EWL ≥ 50% is associated with a more optimal body composition outcome than EWL < 50%. LBM reduction occurs predominantly in the early post-operative period.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11695-022-06128-3.

Is the Peri-Bariatric Surgery Exercise Program Effective in Adults with Obesity: a Systematic Review

The number of people with obesity continues to increase. Bariatric surgery is the most effective treatment for severe obesity. However, this surgery also has disadvantages, such as an increased risk of excessive loss of fat-free mass, lean body mass, and muscle mass compared to other weight loss interventions. PubMed and Cochrane Library database including articles in English, Dutch, French, and German were used. From the 3609 retrieved references, 20 articles were selected. Compared with the control group, physical exercise improved body mass index (5 of 13 articles), weight loss (7 of 17 articles), functional capacity (2 of 5 articles), muscle strength (1 of 1 article), fat-free mass (3 of 5 articles), cardiorespiratory endurance (4 of 6 articles), and quality of life (2 of 4 articles) in obese patients undergoing BS. Current data is suggestive of positive effects of exercise on body mass index, weight loss, functional capacity, muscle strength, fat-free mass, cardiorespiratory endurance, and quality of life in obese patients undergoing bariatric surgery. However, our conclusions are limited because of the heterogeneity of programs and short studies. Further research is needed to determine the most effective physical exercise program in peri-bariatric surgery.

Comparison of bioimpedance spectroscopy and dual energy X-ray absorptiometry for assessing body composition changes in obese children during weight loss

BACKGROUND

Obesity and age influence the reliability of dual energy X-ray absorptiometry scanning (DEXA) and bioimpedance spectroscopy (BIS). Both are used in clinical settings, but have not been compared for measurements in obese children. We compared DEXA and BIS for evaluating body composition and inherent changes in obese children before and after a 10-month weight loss programme.

METHODS

DEXA and BIS were used to evaluate 130 patients at baseline and 75 at follow-up. We tested agreement between the two techniques using Bland-Altman plots and proportional bias using Passing-Bablok regressions.

RESULTS

The Bland-Altman plots showed wide agreement limits before and after weight loss and when monitoring longitudinal changes. At baseline, the Passing-Bablok regressions revealed a proportional bias for all body compartments. After significant weight loss no proportional bias was found for fat mass and percentage, although BIS systematically underestimated fat mass by 2.9 kg. Longitudinally, no proportional bias was found in the measured changes of absolute fat, fat-free mass and fat-free percentage between both methods, although BIS systematically underestimated fat and fat-free mass by 2.6 and 0.7 kg, respectively.

CONCLUSION

While BIS and DEXA are not interchangeable at baseline, the agreement between the two improved after significant weight loss. Proportional changes in fat mass, fat-free mass and fat-free percentage were similar for both techniques. BIS is a viable alternative to DEXA for future paediatric obesity studies measuring treatment effect at group levels, but is not superior to DEXA and cannot be used for monitoring individual changes due to wide limits of agreement.

External validation of the relative fat mass (RFM) index in adults from north-west Mexico using different reference methods

Background

Analysis of body composition is becoming increasingly important for the assessment, understanding and monitoring of multiple health issues. The body mass index (BMI) has been questioned as a tool to estimate whole-body fat percentage (FM%). Recently, a simple equation described as relative fat mass (RFM) was proposed by Woolcott & Bergman. This equation estimates FM% using two anthropometric measurements: height and waist circumference (WC). The authors state that due to its simplicity and better performance than BMI, RFM could be used in daily clinical practice as a tool for the evaluation of body composition. The aim of this study was to externally validate the equation of Woolcott & Bergman to estimate FM% among adults from north-west Mexico compared with Dual-energy X-ray absorptiometry (DXA) as an alternative to BMI and secondly, to make the same comparison using air displacement plethysmography (ADP), Bioelectrical Impedance Analysis (BIA) and a 4-compartment model (4C model).

Methods

Weight, height and WC were measured following standard procedures. The RFM index was calculated for each of the 61 participating subjects (29 females and 32 males, ages 20–37 years). The RFM was then regressed against each of the four body composition methods for estimating FM%.

Results

Compared with BMI, RFM was a better predictor of FM% determined by each of the body composition methods. In terms of precision the best equation was RFM regressed against DXA (y = 1.12 + 0.99 x; R² = 0.84 p<0.001). Accuracy (represented by the closeness to the zero-intercept) was 1.12 (95% CI: -2.44, to 4.68) and thus, not significantly different from zero. For the rest of the methods, precision in the prediction of FM% was improved compared to BMI, with significant increases in the R² and reduction of the root mean squared error (RMSE). However, the intercepts of each regression did not show accuracy since they were different from zero, for ADP: -9.95 (95%CI: -15.7 to -4.14), for BIA: -12.6 (95%CI: -17.5 to -7.74) and for the 4C model: -13.6 (95%CI: -18.6 to -8.60). Irrespectively, FM% measured by each of the body composition methods was higher for DXA than the other three methods (p<0.001).

Conclusions

This external validation proved that the performance of the RFM equation used in this study to estimate FM% was more consistent than BMI in this Mexican population, showing a stronger correlation with DXA than with the other body composition methods.

Agreement Between Body Composition Assessed by Bioelectrical Impedance Analysis and Doubly Labeled Water in Obese Women Submitted to Bariatric Surgery : Body Composition, BIA, and DLW

INTRODUCTION

Bariatric surgery has a significant influence on body composition (BC), which should be monitored. However, there is a need to recommend low-cost practical methods, with good estimation of BC for class III obese and/or bariatric patients.

OBJECTIVE

The aim of this study was to determine accuracy and agreement between BC assessed by direct segmental multifrequency bioelectrical impedance analysis (DSM-BIA) and doubly labeled water (DLW) as reference method.

MATERIAL AND METHODS

Twenty class III obese women (age 29.3 ± 5.1 years; body mass index 44.8 ± 2.4 kg/m²) underwent Roux-en-Y gastric bypass surgery. BC (fat mass [FM], fat-free mass [FFM], and total body water [TBW]) was assessed by InBody 230 and DLW in the following periods: before and 6 and 12 months after surgery. Accuracy between the methods was evaluated by the bias and root mean square error. Pearson's correlation, concordance correlation coefficient (CCC), and Bland-Altman method were used to evaluate agreement between the methods.

RESULTS

Correlations were significant (p < 0.001) and CCC was good/excellent between both methods for the evaluation of FM (r = 0.84-0.92, CCC = 0.84-0.95), FFM (r = 0.73-0.90, CCC = 0.68-0.80), and TBW (r = 0.76-0.91, CCC = 0.72-0.81) before and after bariatric surgery. In addition, no significant bias was observed between DSM-BIA and DLW for FM (mean error [ME] = - 1.40 to 0.06 kg), FFM (ME = 0.91-1.86 kg), and TBW (ME = 0.71-1.24 kg) measurements.

CONCLUSION

The DSM-BIA was able to estimate the BC of class III obese women submitted to bariatric surgery with values consistent with those of the DLW method.

A Gut Check Explains Improved Glucose Metabolism after Surgery

Biliopancreatic diversion (BPD) surgery leads to more frequent diabetes remission than Roux-en-Y gastric bypass (RYGB). In this issue, Harris et al. (2019) compare each surgery after careful matching for percentage weight loss and find the gut as a major site of difference between the effects of the two surgeries.

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.

Fat-Free Mass and Skeletal Muscle Mass Five Years After Bariatric Surgery

OBJECTIVE

This study investigated changes in fat-free mass (FFM) and skeletal muscle 5 years after surgery in participants from the Longitudinal Assessment of Bariatric Surgery-2 trial.

METHODS

A three-compartment model assessed FFM, and whole-body magnetic resonance imaging (MRI) quantified skeletal muscle mass prior to surgery (T0) and 1 year (T1), 2 years (T2), and 5 years (T5) postoperatively in 93 patients (85% female; 68% Caucasian; age 44.2 ± 11.6 years) who underwent gastric bypass (RYGB), sleeve gastrectomy, or adjustable gastric band. Repeated-measures mixed models were used to analyze the data.

RESULTS

Significant weight loss occurred across all surgical groups in females from T0 to T1. FFM loss from T0 to T1 was greater after RYGB (mean ± SE: -6.9 ± 0.6 kg) than adjustable gastric band (-3.5 ± 1.4 kg; P < 0.05). Females with RYGB continued to lose FFM (-3.3 ± 0.7 kg; P < 0.001) from T1 to T5. A subset of males and females with RYGB and MRI-measured skeletal muscle showed similar initial FFM loss while maintaining FFM and skeletal muscle from T1 to T5.

CONCLUSIONS

Between 1 and 5 years following common bariatric procedures, FFM and skeletal muscle are maintained or decrease minimally. The changes observed in FFM and muscle during the follow-up phase may be consistent with aging.

Fluid balance concepts in medicine: Principles and practice

The regulation of body fluid balance is a key concern in health and disease and comprises three concepts. The first concept pertains to the relationship between total body water (TBW) and total effective solute and is expressed in terms of the tonicity of the body fluids. Disturbances in tonicity are the main factor responsible for changes in cell volume, which can critically affect brain cell function and survival. Solutes distributed almost exclusively in the extracellular compartment (mainly sodium salts) and in the intracellular compartment (mainly potassium salts) contribute to tonicity, while solutes distributed in TBW have no effect on tonicity. The second body fluid balance concept relates to the regulation and measurement of abnormalities of sodium salt balance and extracellular volume. Estimation of extracellular volume is more complex and error prone than measurement of TBW. A key function of extracellular volume, which is defined as the effective arterial blood volume (EABV), is to ensure adequate perfusion of cells and organs. Other factors, including cardiac output, total and regional capacity of both arteries and veins, Starling forces in the capillaries, and gravity also affect the EABV. Collectively, these factors interact closely with extracellular volume and some of them undergo substantial changes in certain acute and chronic severe illnesses. Their changes result not only in extracellular volume expansion, but in the need for a larger extracellular volume compared with that of healthy individuals. Assessing extracellular volume in severe illness is challenging because the estimates of this volume by commonly used methods are prone to large errors in many illnesses. In addition, the optimal extracellular volume may vary from illness to illness, is only partially based on volume measurements by traditional methods, and has not been determined for each illness. Further research is needed to determine optimal extracellular volume levels in several illnesses. For these reasons, extracellular volume in severe illness merits a separate third concept of body fluid balance.

Relation of Disease with Standardized Phase Angle among Older Patients

BACKGROUND

A low phase angle (PA) has been associated with negative outcome in specific diseases. However, many patients suffer from several co-morbidities. This study aims at identifying the impact of the type and the severity of diseases on PA in a retrospective cohort study of older people.

METHODS

We included all people ≥65 years who underwent a PA measurement (Nutriguard®) between 1990 and 2011 at the Geneva University Hospitals. PA was standardized for gender, age and body mass index according to German reference values. Co-morbidities were reported in form of the Cumulative Illness Rating Scale which considers 14 different organs/systems (disease categories), each rated from 0 (healthy) to 4 (severe illness) (severity grades). The association between the diseases categories and standardized PA was evaluated by a multivariate linear regression. For each significant disease category, we performed univariate regression models. The adjusted R2 was used to identify the best predictors of standardized PA. We considered that the severity grade affected standardized PA if there was a progressive decrease in the regression coefficients.

RESULTS

We included 1181 people (37% women). The multivariate regression model showed that the disease categories explain 17% of the variance of standardized PA. Many disease categories affect standardized PA and the ones best associated with standardized PA were the hematopoietic and vascular (R2 7.4%), the musculo-skeletal (R2 5.5%) and the respiratory (R2 4.0%) diseases. The regression coefficients in the univariate linear regression model decreased progressively with higher severity grades in respiratory (-0.15, -0.27, -0.55, -0.67) and musculo-skeletal diseases (-0.09, -0.46, -0.85, -0.86).

CONCLUSIONS

Many different diseases affect standardized PA. The higher the severity grade in musculo-skeletal and respiratory diseases, the lower is the standardized PA.

Evaluation of Advanced Bioimpedance Spectroscopy Models for Measuring Body Composition in Healthy Adults (NHANES 1999-2004) and Those Undergoing Massive Weight Loss Following Roux-en-Y Gastric Bypass Surgery

INTRODUCTION

Bioimpedance spectroscopy (BIS) devices utilize biophysical modeling to generate body composition data. The addition of body mass index (BMI) to modified Xitron-Hanai-based mixture equations improved BIS estimates of intracellular water (ICW), particularly at the extremes of BMI. A 3-compartment model for distinguishing excess fluid (ExF) from normally hydrated lean (NHLT) and adipose tissue may further improve BIS estimates.

OBJECTIVE

We aimed to validate a BIS approach based on the Chamney model for determining fat mass (FM) in healthy individuals (NHANES) and for measuring FM changes in individuals undergoing massive weight loss.

METHODS

Using adult NHANES 1999-2004 (2821 female, 3063 male) and longitudinal pre-to-post-RYGB (15F) data, we compared dual-energy-X-ray absorptiometry (DXA) and BIS for FM. We applied BIS adiposity-corrected values to Chamney equations for normally hydrated lean and adipose tissue (NHLT, NHAT) and FM. Method agreement was evaluated by correlations, paired t-tests, root mean square error (RMSE), Bland-Altman (B-A) analysis, and concordance correlation coefficients (CCC).

RESULTS

Method agreement between BIS and DXAFM was good in healthy adults (r=0.96, CCC=0.93, p<.0001), and pre-to-post-RYGB (r=0.93-0.98, CCC=0.81-0.86, p<.001). Although cross-sectional FM measures differed, FM change measures post-RYGB did not (35.6±8.9 vs. 35.2±9.2 kg, BIS vs. DXA) and agreed well (r=0.84, p<.0001). The 15 subjects with follow-up measurements at 1 year lost 11.5±9.8 kg FFM by DXA, but only 1.3±2.5 kg of NHLT by BIS, suggesting that the FFM loss may have been mostly adipose tissue water.

CONCLUSIONS

Incorporation of the Chamney model into BIS algorithms is a major conceptual advancement for assessing and monitoring body composition. Its ability to differentiate ICW and extracellular water (ECW) in NHLT and NHAT, as well as excess ECW is promising, and would facilitate lean tissue monitoring in obesity and acute/chronic disease.

Effect of a randomised 12-week resistance training programme on muscular strength, cross-sectional area and muscle quality in women having undergone Roux-en-Y gastric bypass

The purpose of this study was to examine the effect of a 12-week resistance training programme on fat-free mass (FFM), muscle cross-sectional area, muscular strength and muscle quality in women who underwent Roux-en-Y gastric bypass surgery. Participants were 16 women (mean age = 44.9 ± 10.2 years) from bariatric surgical groups who were randomly assigned into either a control or an intervention group. Air displacement plethysmography measured FFM and magnetic resonance imaging measured quadriceps muscle cross-sectional area and whole thigh muscle cross-sectional area. Muscular strength and quality was assessed using an estimated 1-Repetition Maximum assessment. All measurements were collected twice, at baseline and at a 12-week follow-up. There were significantly greater improvements in leg press strength (mean differences = 55.4%, P < 0.001, Cohen's d = 2.4), leg extension strength (mean differences = 18.0%, P = 0.014, Cohen's d = 0.86) and leg press muscle quality (mean differences = 54.5%, P < 0.001, Cohen's d = 1.9) in the intervention group compared to the control group following the resistance training programme. The resistance training intervention significantly improved muscular strength and quality; however, it did not illicit changes in FFM or muscle cross-sectional area in women who underwent Roux-en-Y gastric bypass surgery.

Changes in glycemia, insulin and gut hormone responses to a slowly ingested solid low-carbohydrate mixed meal after laparoscopic gastric bypass or band surgery

OBJECTIVE

To evaluate early changes in glycemia, insulin physiology and gut hormone responses to an easily tolerated and slowly ingested solid, low-carbohydrate mixed meal test (MMT) following laparoscopic adjustable gastric banding (LAGB) or Roux-en-Y gastric bypass (RYGB) surgery.

SUBJECTS/METHODS

This was a prospective non-randomized study. Plasma glucose, insulin and c-peptide (to estimate hepatic insulin extraction; %HIE), incretins (GIP, aGLP-1) and pancreatic polypeptide (PP) responses to the MMT were measured at 4-8 weeks before and after surgery in obese, metabolically healthy patients (RYGB=10F or LAGB =7F/1M). Supplementary clamp data on basal endogenous glucose production (EGP) and peripheral insulin action (Rd=rate of glucose disposal) and metabolic clearance rates of insulin (MCR-INS) were available in five of the RYGB patients. Repeated measures were appropriately accounted for in the analyses.

RESULTS

Following LAGB surgery, C-peptide and insulin MMT profiles (P=0.004 and P=0.0005, respectively) were lower with no change in %HIE (P=0.98). In contrast, in RYGB subjects, both fasting glucose and insulin (Δ=-0.66 mmol l^-1, P⩽0.05 and Δ=-44.4 pmol l^-1, P⩽0.05, respectively) decreased, and MMT glucose (P<0.0001) and insulin (P=0.001) but not c-peptide (P= 0.69) decreased. Estimated %HIE increased at fasting (Δ=8.4%, P⩽0.05) and during MMT (P=0.0005). Early (0-20 min) prandial glucose (0.27±0.26 versus 0.006±0.21 mmol l^-1, P⩽0.05) and insulin (63(48, 66) versus 18(12, 24) pmol l^-1, P⩽0.05) responses increased after RYGB. RYGB altered the trajectory of prandial aGLP-1 responses (treatment × trajectory P=0.02), and PP was lower (P<0.0001). Clamp data in a subset of RYGB patients showed early improvement in basal EGP (P=0.001), and MCR-INS (P=0.015).

CONCLUSION

RYGB results in distinctly different changes in plasma glucose, insulin and gut hormone response patterns to a solid, slowly ingested low-carbohydrate MMT versus LAGB. Altered nutrient delivery, along with indirect evidence for changes in hepatic and peripheral insulin physiology, are consistent with the greater early improvement in glycemia observed after RYGB versus LAGB surgery.

Effect on Nitrogen Balance, Thermogenesis, Body Composition, Satiety, and Circulating Branched Chain Amino Acid Levels up to One Year after Surgery: Protocol of a Randomized Controlled Trial on Dietary Protein During Surgical Weight Loss

Background

Bariatric surgery (BS), the most effective treatment for severe obesity, typically results in 40-50 kg weight loss in the year following the surgery. Beyond its action on protein metabolism, dietary protein intake (PI) affects satiety, thermogenesis, energy efficiency, and body composition (BC). However, the required amount of PI after surgical weight loss is not known. The current daily PI recommendation for diet-induced weight loss is 0.8 g/kg ideal body weight (IBW) per day, but whether this amount is sufficient to preserve fat-free mass during active surgical weight loss is unknown.

Objective

To evaluate the effect of a 3-month dietary protein supplementation (PS) on nitrogen balance (NB), BC, energy expenditure, and satiety in women undergoing either gastric bypass or vertical sleeve gastrectomy.

Methods

In this randomized prospective study, participants will be randomized to a high protein supplementation group (1.2 g/kg IBW per day) or standard protein supplementation group (0.8 g/kg IBW per day) based on current guidelines. Outcome measures including NB, BC, circulating branched chain amino acids, and satiety, which will be assessed presurgery, and at 3-months and 12-months postsurgery.

Results

To date, no studies have examined the effect of dietary PS after BS. Current guidelines for PI after surgery are based on weak evidence.

Conclusions

The results of this study will contribute to the development of evidence-based data regarding the safe and optimal dietary PI and supplementation after BS.

Trial Registration

Clinicaltrials.gov NCT02269410; http://clinicaltrials.gov/ct2/show/NCT02269410 (Archived by WebCite at http://www.webcitation.org/6m2f2QLeg).

Efficacy of a liquid low-energy formula diet in achieving preoperative target weight loss before bariatric surgery

A preoperative weight loss of 8 % is a prerequisite to undergo bariatric surgery (BS) in Denmark. The aim of the present study was to evaluate the efficacy of a 7- or an 11-week low-energy diet (LCD) for achieving preoperative target weight before BS. A total of thirty obese patients (BMI 46·0 (sd 4·4) kg/m(2)) followed an LCD (Cambridge Weight Plan(®), 4184 kJ/d (1000 kcal/d)) for 7 or 11 weeks as preparation for BS. Anthropometric measurements including body composition (dual-energy X-ray absorptiometry), blood parameters and blood pressure were assessed at weeks 0, 7 and 11. At week 7, the majority of patients (77 %) had reached their target weight, and this was achieved after 5·4 (sem 0·3) weeks. Mean weight loss was 9·3 (sem 0·5) % (P < 0·01) and consisted of 41·6 % fat-free mass (FFM) and 58·4 % fat mass. The weight loss was accompanied by a decrease in systolic and diastolic blood pressure (7·1 (sem 2·3) and 7·3 (sem 1·8) mmHg, respectively, all P < 0·01) as well as an improved metabolic profile (8·2 (sem 1·8) % decrease in fasting glucose (P < 0·01), 28·6 (sem 6·4) % decrease in fasting insulin (P < 0·01), 23·1 (sem 2·2) % decrease in LDL (P < 0·01), and 9·7 (sem 4·7) % decrease in TAG (P < 0·05)). Weight, FFM and fat mass continued to decrease from week 7 to 11 (all P < 0·01), whereas no additional improvements was observed in the metabolic parameters. Severely obese patients can safely achieve preoperative target weight on an LCD within 7 weeks as part of preparation for BS. However, the considerable reduction in FFM in severely obese subjects needs further investigation.

Long-Term Body Composition Changes in Women Following Roux-en-Y Gastric Bypass Surgery

BACKGROUND

Although most individuals experience successful weight loss following Roux-en-Y gastric bypass (RYGB), weight regain is a concern, the composition of which is not well documented. Our aim was to evaluate changes in body composition and handgrip strength as a measure of functional status in participants from a previous 1-year post-RYGB longitudinal study who had undergone RYGB approximately 9 years prior.

METHODS

Five women from an original larger cohort were monitored pre-RYGB and 1.5 months, 6 months, 1 year, and 9 years post-RYGB. Body composition was assessed at all time points using dual energy x-ray absorptiometry and multiple dilution. Handgrip strength was measured using a digital isokinetic hand dynamometer (Takei Scientific Instruments, Ltd, Tokyo, Japan).

RESULTS

Mean time to final follow-up was 8.7 years. Lean soft tissue (LST) loss over the ~9-year period was on average 11.9 ± 5.6 kg. Compared with 1-year post-RYGB, 9-year LST was 4.4 ± 3.0 kg lower ( P = .03). Fat-free mass decreased over the 9-year period by 12.6 ± 5.8 kg. Mean fat mass (FM) decreased from 75.4 ± 22.6 kg pre-RYGB to 35.5 ± 21.5 kg 1 year post-RYGB but then trended toward an increase of 8.6 ± 7.0 kg between 1 year and 9 years post-RYGB ( P = .053). Loss of LST was correlated with loss of handgrip strength ( r = 0.64, P = .0005).

CONCLUSION

The continued loss of lean mass associated with decreased handgrip strength occurring with long-term trend toward FM regain post-RYGB is concerning. The loss of LST and functional strength carries particular implications for the aging bariatric population and should be investigated further.

Changes of body composition in patients with BMI 23-50 after tailored one anastomosis gastric bypass (BAGUA): influence of diabetes and metabolic syndrome

BACKGROUND

The use of bariatric surgery to treat diabetes mellitus (DM) requires procedures developed for morbid obese in patients with normal and over-weight. Therefore, we started tailoring one anastomosis gastric bypass (BAGUA) adapted to each patient. This study analyzes changes in body composition (BC) of patients with BMI 23-50 after BAGUA as well as influence of DM and MS.

METHODS

We studied 79 (37 diabetic and 42 non-diabetic) patients (BMI 23-50) who completed all evaluation appointment (preoperative, 10 days, 1, 3, 6, and 12 months) after tailored BAGUA for obesity, diabetes, or diabesity. Patients were classified according to BMI (23-29, 30-34, 35-50) and bearing or not diabetes. Variables are components of BC as well as DM and MS.

RESULTS

Preoperatively, mean values of weight varied 37 kg (78-115 kg), muscle mass (MM) 8 kg (54-62 kg), while fat mass (FM) 30 kg (22-53 kg). Basal metabolism (BM) was higher in diabetic. After surgery, percentage (%) of excess weight loss (%EWL) ranged from 76 % (BMI 35-50) to 128 % (BMI 23-29), FM 56 % (BMI 23-29) to 65 % (BMI 35-50), without differences bearing DM. MM 12 % (non-diabetics BMI 30-34) to 17 % (diabetics BMI 35-50) and visceral fat (VF) 50 % (diabetics BMI 30-34) to 56 % (non-diabetics BMI 35-50).

CONCLUSIONS

After tailored BAGUA, MM maintains steady while FM is highly reduced and variable. BM is reduced in all groups. Diabetics lose less weight and VF but more MM than non-diabetic patients. Preoperative presence of MS influences the changes in BC.

Validity of bioelectrical impedance analysis for measuring changes in body water and percent fat after bariatric surgery

BACKGROUND

Few studies have validated bioelectrical impedance analysis (BIA) following bariatric surgery.

METHODS

We examined agreement of BIA (Tanita 310) measures of total body water (TBW) and percent body fat (%fat) before (T0) and 12 months (T12) after bariatric surgery, and change between T0 and T12 with reference measures: deuterium oxide dilution for TBW and three-compartment model (3C) for %fat in a subset of participants (n = 50) of the Longitudinal Assessment of Bariatric Surgery-2.

RESULTS

T0 to T12 median (IQR) change in deuterium TBW and 3C %fat was -6.4 L (6.4 L) and -14.8% (13.4%), respectively. There were no statistically significant differences between deuterium and BIA determined TBW [median (IQR) difference: T0 -0.1 L (7.1 L), p = 0.75; T12 0.2 L (5.7 L), p = 0.35; Δ 0.35 L(6.3 L), p = 1.0]. Compared with 3C, BIA underestimated %fat at T0 and T12 [T0 -3.3 (5.6), p < 0.001; T12 -1.7 (5.2), p = 0.04] but not change [0.7 (8.2), p = 0.38]. Except for %fat change, Bland-Altman plots indicated no proportional bias. However, 95% limits of agreement were wide (TBW 15-22 L, %fat 19-20%).

CONCLUSIONS

BIA may be appropriate for evaluating group level response among severely obese adults. However, clinically meaningful differences in the accuracy of BIA between individuals exist.

The multidomain mobility lab in older persons: from bench to bedside. The assessment of body composition in older persons at risk of mobility limitations

With body composition it is possible to divide human body in compartments on the basis of different physical properties. The two level body composition model subdividing the whole body in fat mass and fat free mass is the most used in epidemiological and clinical studies in the elderly. Body composition techniques may be used to study ageing process. Changes in body composition occur as part of the normal ageing process and are associated with important effects on health and function. It has been shown that body composition changes with aging, with an increase in fat mass and a decrease in muscle mass, have important consequences on health and physical disability. Moreover body fat distribution changes with adverse metabolic profiles and increased cardiovascular risk. The purpose of this review is to describe the basic principles and techniques for fat free mass and fat mass evaluation, highlighting the advantages and limitations of different available body composition methods.

Review article: The nutritional and pharmacological consequences of obesity surgery

BACKGROUND

Obesity surgery is acknowledged as a highly effective therapy for morbidly obese patients. Beneficial short-term effects on common comorbidities are practically undisputed, but a growing data pool from long-term follow-up reveals increasing evidence of potentially severe nutritional and pharmacological consequences.

AIMS

To assess the prevalence, causes and symptoms of complications after obesity surgery, to elucidate and compare therapy recommendations for macro- and micronutrient deficiencies, and to explore surgically-induced effects on drug absorption and bioavailability, discussing ramifications for long-term therapy and prophylaxis.

METHODS

PubMed, Embase and MEDLINE were searched using terms including, but not limited to, bariatric surgery, gastric bypass, obesity surgery and Roux-en-Y, coupled with secondary search terms, e.g. anaemia, micronutrients, vitamin deficiency, bacterial overgrowth, drug absorption, pharmacokinetics, undernutrition. All studies in English, French or German published January 1980 through March 2014 were included.

RESULTS

Macro- and micronutrient deficiencies are common after obesity surgery. The most critical, depending on surgical technique, are hypoalbuminemia (3-18%) and deficiencies of vitamins B1 (≤49%), B12 (19-35%) and D (25-73%), iron (17-45%) and zinc (12-91%). Many drugs commonly administered to obese patients (e.g. anti-depressants, anti-microbials, metformin) are subject to post-operative and/or PPI-associated changes affecting bioavailability and absorption.

CONCLUSIONS

Complications are associated with pre-operative and/or post-operative malnutrition or procedure-related changes in intake, absorption and drug bioavailability. The high prevalence of nutrient deficiencies after obesity surgery makes life-long nutritional monitoring and supplementation essential. Post-operative changes to drug absorption and bioavailability in bariatric patients cast doubt on the validity of standard drug dosage and administration recommendations.

Bone metabolism after bariatric surgery

Bariatric surgery is a popular and effective treatment for severe obesity but may have negative effects on the skeleton. This review summarizes changes in bone density and bone metabolism from animal and clinical studies of bariatric surgery, with specific attention to Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG). Skeletal imaging artifacts from obesity and weight loss are also considered. Despite challenges in bone density imaging, the preponderance of evidence suggests that bariatric surgery procedures have negative skeletal effects that persist beyond the first year of surgery, and that these effects vary by surgical type. The long-term clinical implications and current clinical recommendations are presented. Further study is required to determine mechanisms of bone loss after bariatric surgery. Although early studies focused on calcium/vitamin D metabolism and mechanical unloading of the skeleton, it seems likely that surgically induced changes in the hormonal and metabolic profile may be responsible for the skeletal phenotypes observed after bariatric surgery.

Dual-energy X-ray absorptiometry measured regional body composition least significant change: effect of region of interest and gender in athletes

Dual-energy X-ray absorptiometry (DXA) is widely used to evaluate body composition in athletes. Knowledge of measurement precision is essential for monitoring body composition changes over time. This study begins characterizing DXA body composition precision in 60 (30 males and 30 females) Division 1 athletes focusing on gender, regional, and tissue type differences. Two total body scans with repositioning between were performed on the same day. Least significant change (LSC) for the root-mean-square deviation (LSCRMSD) and the percent coefficient of variation (LSC%CV) for total, lean, and fat mass was calculated for 6 regions of interest. The effect of gender, region, tissue type, and mass on the standard deviation (SD) and percent coefficient of variation (%CV) between the 2 scans was evaluated using repeated measures regression analysis. Statistically significant effects of gender, region, tissue type, and mass on SD and %CV were noted. To generalize, a nonlinear positive relationship between LSCRMSD and mass and a nonlinear negative relationship between LSC%CV and mass were observed. In conclusion, DXA body composition LSC varies among genders, regions, tissues, and mass. As such, when evaluating serial body composition in athletes, especially if assessing regional change, knowledge of precision in individuals of similar body size and gender to the population of interest is needed.

Serum 25(OH) vitamin D concentration changes after Roux-en-Y gastric bypass surgery

OBJECTIVE

To describe serum 25(OH)D changes after Roux-en-Y gastric bypass (RYGB) and to determine if fat mass (FM) loss and vitamin D intake are associated with changes in serum levels.

DESIGN AND METHODS

The relationship between serum 25(OH)D and 1) FM, 2) weight, 3) % excess weight loss (EWL), and 4) BMI was investigated after controlling for potential confounders using a mixed effects linear model in 20 women before and up to 1-year post-RYGB. Subcutaneous (SAT) and visceral adipose tissue (VAT) vitamin D concentrations at time of RYGB were also evaluated.

RESULTS

Weight and FM decreased 1-year after surgery by 45 ± 1 kg and 37 ± 1 kg, respectively while 25(OH)D increased by 10 ± 2 ng mL(-1) . Weight, FM, BMI, and %EWL changes were associated with 25(OH)D change. VAT had an average 21% more vitamin D per gram than SAT and concentrations were highly correlated.

CONCLUSIONS

Although weight loss may lead to increased serum 25(OH)D after RYGB, low levels remain a concern in some patients 1-year postsurgery. Additional research is needed to clarify the relationship between adipose storage of vitamin D and serum 25(OH)D in obesity, and how that relationship might change after surgery. This could lead to improved clinical management of vitamin D in this ever-growing clinical population.

The Official Positions of the International Society for Clinical Densitometry: Indications of Use and Reporting of DXA for Body Composition

The technique of body composition by dual-energy X-ray absorptiometry (DXA) has been used for several years in the research environment. Its ability to accurately and precisely measure lean, fat, and mineral composition in various body compartments has been well validated. Furthermore, the technique is widely available to clinical patients on existing DXA instruments throughout the world through the use of specific software packages and scanning algorithms. There have been few clear statements regarding the clinical indications for body composition measurement in patients outside the research setting. This is in part because of the lack of specific documented interventions that would be affected by body composition test results, beyond usual clinical advice. We have examined a few of the most common, specific scenarios (HIV therapy, sarcopenia, bariatric surgery, obesity) and proposed indications for body composition assessment. We have also discussed contraindications to body composition testing.

Effects of RYGB on energy expenditure, appetite and glycaemic control: a randomized controlled clinical trial

OBJECTIVES

Increased energy expenditure (EE) has been proposed as an important mechanism for weight loss following Roux-en-Y gastric bypass (RYGB). However, this has never been investigated in a controlled setting independent of changes in energy balance. Similarly, only few studies have investigated the effect of RYGB on glycaemic control per se. Here, we investigated the effect of RYGB on EE, appetite, glycaemic control and specific signalling molecules compared with a control group in comparable negative energy balance.

SUBJECTS/METHODS

Obese normal glucose-tolerant participants were randomized to receive RYGB after 8 (n=14) or 12 weeks (n=14). The protocol included a visit at week 0 and three visits (weeks 7, 11 and 78) where 24-h EE, appetite and blood parameters were assessed. Participants followed a low-calorie diet from weeks 0-11, with those operated at week 12 serving as a control group for those operated at week 8.

RESULTS

Compared with controls, RYGB-operated participants had lower body composition-adjusted 24-h EE and basal EE 3 weeks postoperatively (both P<0.05) but EE parameters at week 78 were not different from preoperative values (week 7). Surgery changed the postprandial response of glucagon-like peptide-1 (GLP-1), peptide YY3-36 (PYY), ghrelin, cholecystokinin, fibroblast growth factor-19 and bile acids (all P<0.05). Particularly, increases in GLP-1, PYY and decreases in ghrelin were associated with decreased appetite. None of HOMA-IR (homeostasis model assessment-estimated insulin resistance), Matsuda index, the insulinogenic index, the disposition index and fasting hepatic insulin clearance were different between the groups, but RYGB operated had lower fasting glucose (P<0.05) and the postprandial glucose profile was shifted to the left (P<0.01).

CONCLUSIONS

Our data do not support that EE is increased after RYGB. More likely, RYGB promotes weight loss by reducing appetite, partly mediated by changes in gastrointestinal hormone secretion. Furthermore, we found that the early changes in glycaemic control after RYGB is to a large extent mediated by caloric restriction.

Validity of extracellular water assessment with saliva samples using plasma as the reference biological fluid

Extracellular water (ECW) assessment is based on dilution techniques, commonly using blood sampling. However, plasma collection is an invasive procedure. We aimed to validate the use of saliva for ECW estimation by the bromide dilution technique using plasma as the reference method, in a sample of elite athletes. A total of 89 elite athletes with a mean age of 20.4 ± 4.4 years were evaluated. Baseline samples were collected before sodium bromide oral dose administration, and enriched samples were collected 3 h post-dose administration. The bromide concentration was assessed by high-performance liquid chromatography. Comparison of means, concordance coefficient correlation (CCC), multiple regression and Bland-Altman analysis were performed. The ECW from saliva explained 91% of the variance in ECW by plasma with a standard error of estimation of 0.91 kg. The CCC between alternative and reference methods was 0.952. No significant trend was observed between the mean and difference of the methods, with limits of agreement ranging between -1.5 and 2.1 kg. These findings reveal that bromide dilution volume calculated from saliva samples is a valid noninvasive method for ECW assessment in elite athletes.

Patients with cirrhosis and ascites have false values of bone density: implications for the diagnosis of osteoporosis

The effect of ascites on bone densitometry has been assessed in 25 patients with advanced cirrhosis, and it was concluded that ascites over 4 l causes inaccuracy of BMD measurements, particularly at the lumbar spine. This fact must be considered when assessing bone mass in patients with decompensated cirrhosis.

INTRODUCTION

Bone mineral density (BMD) measured by dual-energy x-ray absorptiometry (DXA) is the best procedure for assessment of osteoporosis and fracture risk, but BMD values at the central skeleton may be influenced by changes in soft tissues. Therefore, we have studied the effect of ascites on BMD.

METHODS

BMD was measured by DXA at the lumbar spine, femoral neck and total hip, just before and shortly after therapeutic paracentesis in 25 patients with advanced liver cirrhosis. Changes in BMD, lean and fat mass, abdominal diameter and weight, as well as the amount of removed ascites were measured.

RESULTS

The amount of drained ascites was 6.6 ± 0.5 l (range: 3.0 to 12.7 l). After paracentesis, BMD increased at the lumbar spine (from 0.944 ± 0.035 to 0.997 ± 0.038 g/cm(2), p < 0.001) and at the total hip (from 0.913 ± 0.036 to 0.926 ± 0.036 g/cm(2), p < 0.01). Patients with a volume of drained ascites higher than 4 l showed a significant increase in lumbar BMD (7.0%), compared with patients with a lower amount (1.5%) (p < 0.03). The decrease in total soft tissue mass correlated with the amount of removed ascites (r = 0.951, p < 0.001). Diagnosis of osteoporosis or osteopenia changed after paracentesis in 12% of patients.

CONCLUSION

Ascites over 4 l causes inaccuracy of BMD measurements, particularly at the lumbar spine. This fact must be considered when assessing bone mass in patients with advanced cirrhosis.

Body fat and fat-free mass measured by bioelectric impedance spectroscopy and dual-energy X-ray absorptiometry in obese and non-obese adults

The aim of the present study was to compare body fat mass (FM) and fat-free mass (FFM) estimates by bioelectric impedance spectroscopy (BIS), with respective estimates by dual-energy X-ray absorptiometry (DXA), in obese and non-obese subjects. Body composition was measured in ninety-three obese and non-obese men and women by BIS device, BodyScout (Fresenius Kabi, Bad Homburg, Germany) and DXA device, Lunar iDXA (GE Healthcare, Madison, WI, USA). Mean difference between the methods was analysed by t tests, and Bland-Altman plots were generated to further examine the differences between the methods. Mean difference between the estimates by DXA and BIS (ΔDXA - BIS and Bland-Altman 95 % limits of agreement) were as follows: FM 4·1 ( - 2·9, 11·2) kg and 4·5 ( - 2·9, 11·8) %, FFM - 4·1 ( - 11·2, 2·9) kg and - 4·5 ( - 11·9, 2·9) %, indicating large inter-individual variation and statistically significant underestimation of FM and overestimation of FFM by BIS, as compared to DXA. The underestimation of FMkg (FM measured in kg) and overestimation of FFMkg (FFM measured in kg) were more pronounced in men than in women, and the underestimation of FM% (FM measured in percent) and overestimation of FFM% (FFM measured in percent) were more pronounced in normal weight (BMI = 20·0-24·9 kg/m2) than in overweight and obese (BMI ≥ 25·0 kg/m2) subjects. BIS may be suitable for classification of a population into groups according to FM and FFM. However, the large inter-individual variation suggests that this BIS device with the proprietary software is insufficient for estimation of single individual body FM and FFM.