Fat-free mass is not lower 24 months postbariatric surgery than nonoperated matched controls

Prevalence of low skeletal muscle mass following bariatric surgery

BACKGROUND AND AIMS

Evidence on the occurrence of low skeletal muscle mass (low-SMM) following bariatric surgery (BS) as well as on the impact of low-SMM antedating BS on post-surgical body composition (BC) are scant. In this context, we aimed to prospectively evaluate the prevalence of low-SMM prior to and up to 5 years after BS, and to evaluate pre-surgical low-SMM as an independent risk factor for the presence of low-SMM after BS.

METHODS

Retrospective analysis of prospectively collected database. BC was assessed by bioelectrical impedance analysis (BIA). A BIA-based formula was used to calculate skeletal muscle mass (SMM). Class I and class II low-SMM were defined respectively as a SMM index (SMMI = SMM/height²) value between -1 and -2, or > -2 standard deviations from the gender-specific regression line of the BMI versus the SMMI relationship in our reference group.

RESULTS

A total 952 subjects were included, with BC being available for 877 (92%) subjects at 12 months and for 576 subjects (60%) at 60 months after BS. Prior to surgery, and at 12-, or at 60-months after surgery, class I and class II low-SMM was ascertained respectively in 15.6% and 4.6%, 5.3% and 1.4%, and 16.6% and 6.3% of the study participants. Logistic regression analysis showed that the occurrence of low-SMM at 12- and 60-months follow-up, was independently predicted not only by age at the time of surgery [respectively, HR: 1.052 (95% CI 1.020-1.084), p = 0.001; and 1.042 (95% CI 1.019-1.066); p < 0.001] but also by the presence of low-SMM prior to surgery [respectively, HR: 10.717 (95% CI 5.771-19.904), p < 0.001; and 5.718 (95% CI 3.572-9.153); p < 0.001].

CONCLUSIONS

Our data suggest that a low-SMM phenotype occurs not only in obesity surgery candidates but also after BS, and that low-SMM prior to surgery is an important risk factor for low-SMM throughout post-surgical follow-up.

Long-term body composition improvement in post-menopausal women following bariatric surgery: a cross-sectional and case-control study

OBJECTIVE

Bariatric surgery (BS) induces loss of body fat mass (FM) with an inexorable loss of lean mass (LM). Menopause leads to deleterious changes in body composition (BC) related to estrogen deficiency including LM loss and increase in total and visceral adipose tissue (VAT). This study aims to describe the long-term weight evolution of post-menopausal women after Roux-en-Y gastric bypass (RYGB) and to compare the BC between BS patients vs post-menopausal non-operated women.

DESIGN

Cross-sectional study of 60 post-menopausal women who underwent RYGB ≥2 years prior to the study with nested case-control design.

METHODS

Post-menopausal BS women were matched for age and BMI with controls. Both groups underwent DXA scan, lipids and glucose metabolism markers assessment.

RESULTS

Median follow-up was 7.5 (2-18) years. Percentage of total weight loss (TWL%) was 28.5 ± 10%. After RYGB, LM percentage of body weight (LM%) was positively associated with TWL% and negatively associated with nadir weight. Forty-one post-BS women were age- and BMI-matched with controls. Post-BS patients showed higher LM% (57.7% (±8%) vs 52.5% (±5%), P = 0.001), reduced FM% (39.4% (±8.4%) vs 45.9% (±5.4%), P < 0.01) and lower VAT (750.6 g (±496) vs 1295.3 g (±688), P < 0.01) with no difference in absolute LM compared to controls. While post-BS women showed a better lipid profile compared to controls, no difference was found in glucose markers.

CONCLUSIONS

Post-menopausal women after RYGB have a lower FM and VAT, preserved LM and a better lipid profile compared to controls. Weight loss after RYGB seems to have a persistent positive impact on metabolic health.

Resting Energy Expenditure and Organ-Tissue Body Composition 5 Years After Bariatric Surgery

INTRODUCTION

Bariatric surgery-induced weight loss may reduce resting energy expenditure (REE) and fat-free mass (FFM) disproportionately thereby predisposing patients to weight regain and sarcopenia.

METHODS

We compared REE and body composition of African-American and Caucasian Roux-en-Y gastric bypass (RYGB) patients after surgery with a group of non-operated controls (CON). REE by indirect calorimetry; skeletal muscle (SM), trunk organs, and brain volumes by MRI; and FFM by DXA were measured at post-surgery visits and compared with CON (N = 84) using linear regression models that adjusted for relevant covariates. Ns in RYGB were 50, 42, and 30 for anthropometry and 39, 27, 17 for MRI body composition at years 1, 2, and 5 after surgery, respectively.

RESULTS

Regression models adjusted for age, weight, height, ethnicity, and sex showed REE differences (RYGB minus CON; mean ± s.e.): year 1 (43.2 ± 34 kcal/day, p = 0.20); year 2 (- 27.9 ± 37.3 kcal/day, p = 0.46); year 5 (114.6 ± 42.3 kcal/day, p = 0.008). Analysis of FFM components showed that RYGB had greater trunk organ mass (~ 0.4 kg) and less SM (~ 1.34 kg) than CON at each visit. REE models adjusted for FFM, SM, trunk organs, and brain mass showed no between-group differences in REE (- 15.9 ± 54.8 kcal/day, p = 0.8; - 46.9 ± 64.9 kcal/day, p = 0.47; 47.7 ± 83.0 kcal/day, p = 0.57, at years 1, 2, and 5, respectively).

CONCLUSIONS

Post bariatric surgery patients maintain a larger mass of high-metabolic rate trunk organs than non-operated controls of similar anthropometrics. Interpreting REE changes after weight loss requires an accurate understanding of fat-free mass composition at both the organ and tissue levels.

CLINICAL TRIAL REGISTRATION

Long-term Effects of Bariatric Surgery (LABS-2) NCT00465829.

Anthropometrics by Three-Dimensional Photonic Scanner in Patients with Obesity Before and After Bariatric Surgery

BACKGROUND

We studied body composition by three-dimensional photonic scanning (3DPS) and metabolic biomarkers in a large ethnically diverse cohort of individuals with severe obesity before and after weight loss by Roux-en-Y gastric bypass (RYGB) or adjustable gastric banding (AGB) surgery.

MATERIALS AND METHODS

Male and female participants (n = 95) underwent 3DPS testing in the weeks preceding bariatric surgery (baseline), and 1 year after either RYGB (n = 34) or AGB (n = 9).

RESULTS

Principal component analysis showed that A1C and HDL cholesterol clustered with waist-to-hip ratio (WHR). Both RYGB and AGB surgeries led to similar improvements in A1C and lipids after 1 year. RYGB led to greater decreases in body weight, and in most anthropometric measures, compared with AGB at 1 year. However, after accounting for weight loss differences, RYGB and AGB groups did not differ in regional decreases in circumferences or volumes; the exception was a greater reduction in lean mass in RYGB compared with AGB.

CONCLUSION

Distribution of weight loss, assessed by 3DPS, did not differ between RYGB and AGB, but surgery type predicted change in lean mass at 1 year.

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.

Postprandial Nutrient Handling and Gastrointestinal Hormone Secretion After Roux-en-Y Gastric Bypass vs Sleeve Gastrectomy

BACKGROUND & AIMS

Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) induce substantial weight loss and improve glycemic control in patients with type 2 diabetes, but it is not clear whether these occur via the same mechanisms. We compared absorption rates of glucose and protein, as well as profiles of gastro-entero-pancreatic hormones, in patients who had undergone SG or RYGB vs controls.

METHODS

We performed a cross-sectional study of 12 patients who had undergone sleeve gastrectomy, 12 patients who had undergone RYGB, and 12 individuals who had undergone neither surgery (controls), all in Denmark. Study participants were matched for body mass index, age, sex, and postoperative weight loss, and all had stable weights. They received continuous infusions of stable isotopes of glucose, glycerol, phenylalanine, tyrosine, and urea before and during a mixed meal containing labeled glucose and intrinsically phenylalanine-labeled caseinate. Blood samples were collected for 6 hours, at 10- to 60-minute intervals, and analyzed.

RESULTS

The systemic appearance of ingested glucose was faster after RYGB and SG vs controls; the peak glucose appearance rate was 64% higher after RYGB, and 23% higher after SG (both P < .05); the peak phenylalanine appearance rate from ingested casein was 118% higher after RYGB (P < .01), but similar between patients who had undergone SG and controls. Larger, but more transient increases in levels of plasma glucose and amino acids were accompanied by higher secretion of insulin, glucagon-like peptide 1, peptide YY, and cholecystokinin after RYGB, whereas levels of ghrelin were lower after SG, compared with RYGB and controls. Total 6-hour oral recovery of ingested glucose and protein was comparable among groups.

CONCLUSIONS

Postprandial glucose and protein absorption and gastro-entero-pancreatic hormone secretions differ after SG and RYGB. RYGB was characterized by accelerated absorption of glucose and amino acids, whereas protein metabolism after SG did not differ significantly from controls, suggesting that different mechanisms explain improved glycemic control and weight loss after these surgical procedures. ClinicalTrials.gov ID NCT03046186.

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.

Fat mass, fat-free mass, and resting metabolic rate in weight-stable sleeve gastrectomy patients compared with weight-stable nonoperated patients

BACKGROUND

There is evidence that body composition and resting metabolic rate (RMR) in weight-stable patients after Roux-en-Y gastric bypass and duodenal switch is similar to that of nonoperated individuals within the same body mass index (BMI) interval. Currently, data concerning fat mass (FM), fat-free mass (FFM), and RMR on weight-stable patients after sleeve gastrectomy (SG) are lacking.

OBJECTIVES

To assess FM, FFM, and RMR, in a selected and homogenous population of weight-stable SG patients (WSSG) and compare them with those obtained from healthy normal weight-stable nonoperated (WSNO) volunteers controls of similar sex, age, and BMI.

SETTING

University hospital, Italy.

METHODS

We assessed total weight, FM, and FFM by bioelectrical impedance assay, and RMR by indirect calorimetry, in 70 WSSG patients (47 females, 23 males) at a mean follow-up of 3.2 ± 2.1 years after SG and compared them with 70 healthy WSNO volunteers, as controls (47 females, 23 males).

RESULTS

There was no significant difference between WSSG and WSNO groups concerning total weight (males, 72 ± 2.66 versus 72.8 ± 1.99 kg, P = .0254; females 65.1 ± 2.53 versus 63.7 ± 2.87 kg, P = .0139), FM (males, 17.7 ± 1.53 versus 16.7 ± 1.57 kg, P = .0341; females 19.6 ± 0.50 versus 18.5 ± 2.85 kg, P = .0104), FFM (males, 54.3 ± 3.07 versus 56.1 ± 3.30 kg; P = .049; females 45.5 ± 2.29 versus 45.1 ± 1.13 kg, P = .287), and RMR (males, 1541 ± 121.3 versus 1463 ± 74.4 kcal/d; P = .0118; females 1214 ± 54.9 versus 1250 ± 90.1 kcal/d, P = .0215).

CONCLUSION

At a mean follow-up of 3.2 ± 2.1 years after SG, WSSG patients of both sexes have a FM, FFM, and RMR comparable to that of healthy WSNO individuals within the same age and BMI interval. These findings further support bariatric surgery-induced weight loss as a physiologic process and indicate that young patients, in the setting of an adequate preoperative and postoperative specific diet and moderate physical activity, do not suffer from excessive FFM depletion after SG in the mid-term.

Preserving Healthy Muscle during Weight Loss

Weight loss is the cornerstone of therapy for people with obesity because it can ameliorate or completely resolve the metabolic risk factors for diabetes, coronary artery disease, and obesity-associated cancers. The potential health benefits of diet-induced weight loss are thought to be compromised by the weight-loss-associated loss of lean body mass, which could increase the risk of sarcopenia (low muscle mass and impaired muscle function). The objective of this review is to provide an overview of what is known about weight-loss-induced muscle loss and its implications for overall physical function (e.g., ability to lift items, walk, and climb stairs). The currently available data in the literature show the following: 1) compared with persons with normal weight, those with obesity have more muscle mass but poor muscle quality; 2) diet-induced weight loss reduces muscle mass without adversely affecting muscle strength; 3) weight loss improves global physical function, most likely because of reduced fat mass; 4) high protein intake helps preserve lean body and muscle mass during weight loss but does not improve muscle strength and could have adverse effects on metabolic function; 5) both endurance- and resistance-type exercise help preserve muscle mass during weight loss, and resistance-type exercise also improves muscle strength. We therefore conclude that weight-loss therapy, including a hypocaloric diet with adequate (but not excessive) protein intake and increased physical activity (particularly resistance-type exercise), should be promoted to maintain muscle mass and improve muscle strength and physical function in persons with obesity.