Improved metabolism and body composition beyond normal levels following gastric bypass surgery: a longitudinal study

A multifaceted and inclusive methodology for the detection of sarcopenia in patients undergoing bariatric surgery: an in-depth analysis of current evidence

Bariatric surgery is widely recognized as the most effective intervention for obesity and offers benefits beyond weight loss. However, not all patients achieve satisfactory weight loss, balanced changes in body composition, and resolution of comorbidities. Therefore, thorough pre- and postoperative evaluations are important to predict success and minimize adverse effects. More comprehensive assessments require broadening the focus beyond body weight and fat measurements to consider quantitative and qualitative evaluations of muscles. Introducing the concept of sarcopenia is useful for assessing the degradative and pathological changes in muscles associated with cardiometabolic function, physical performance, and other obesity-related comorbidities in patients undergoing bariatric surgery. However, there is currently no consensus or definition regarding the research and clinical use of sarcopenia in patients undergoing bariatric surgery. Therefore, this review aimed to define the concept of sarcopenia applicable to patients undergoing bariatric surgery, based on the consensus reached for sarcopenia in the general population. We also discuss the methods and significance of measuring muscle mass, quality, and strength, which are key variables requiring a comprehensive assessment.

Impact of gastric bypass surgery on the liver fibrosis of patients with extreme obesity and nonalcoholic fatty liver disease in 30-month follow-up

Roux-en-Y gastric bypass surgery (RYGB) has shown efficacy in weight loss, but its role in liver fibrosis remains unknown and contentious. The present study aimed to investigate the effect of RYGB on liver fibrosis measured by non-invasive methods and assess the impact of weight loss on hepatic fibrosis in the midterm follow-up after RYGB. This longitudinal study was conducted on patients with extreme obesity, and NAFLD referred for RYGB during 2016-2018 for 3 years after their surgery. A liver biopsy was performed intraoperatively. The patient demographics, anthropometrical parameters, biochemical variables, and Liver stiffness (LS) using two-dimensional shear-wave elastography were recorded and analyzed before and in short-term and midterm follow-ups. Fifty-four patients were included with a mean age of 40.3 years; 83.3% were women. At a median follow-up of 30 months (range: 24-36 months), the excessive body mass index loss of the patients was 78.1% and, a significant reduction was seen in LS measurement. Two patients (4%) had worsening showed in the fibrosis stage, 28 (54%) no change, and 24 (42%) showed improvement, 30 months after the surgery. Moreover, the liver fibrosis stage regressed to F0 in 91% of the patients. Hepatic fibrosis resolved in the midterm follow-up in some patients whose fibrosis had progressed and deteriorated in the short-term follow-up. In addition, Liver enzymes were decreased. RYGB seems to be an effective procedure for sustained weight loss and improved liver fibrosis in EO and NAFLD patients in midterm 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.

Atherosclerotic disease burden after bariatric surgery in patients with obesity and type 2 diabetes

BACKGROUND

The rising rates of obesity, along with its associated morbidities, represent an important global health threat. Atherosclerotic cardiovascular disease (ASCVD) is among the most common and hazardous obesity-related morbidity, and it is especially prevalent among those who suffer from type 2 diabetes (T2DM). Bariatric surgery (BS) is known to help with effective weight management and reduce the burden of cardiovascular risk factors, especially T2DM.

METHODS

A nested propensity-matched cohort study was carried out using the Clinical Practice Research Datalink. The cohort included 1186 patients with no past history of ASCVD, 593 of whom underwent BS and 593 propensity-score matched controls, followed up for a mean of 42.7 months. The primary end point was the incidence of new ASCVD; defined as new coronary artery disease (CAD), cerebrovascular disease (CeVD), peripheral arterial disease (PAD), or miscellaneous atherosclerotic disease; secondary end points included primary end point components alone and all-cause mortality.

RESULTS

Patients who underwent BS had significantly lower rates of new ASCVD (hazard ratio [HR] 0.53, confidence interval [CI] 0.30-0.95, P = 0.032. There were no significant differences in rates of CAD, CeVD, and PAD individually across cohorts, but a lower rate of all-cause mortality was observed in the BS cohort (HR 0.36, CI 0.19-0.71, P = 0.003).

CONCLUSIONS

BS was associated with improved ASCVD outcomes and lower mortality in patients with obesity and T2DM. This study provides evidence for increased awareness of potential benefits of BS in the management of obesity by highlighting a potential role in primary prevention for ASCVD.

A longitudinal study of the antilipolytic effect of insulin in women following bariatric surgery

Insulin resistance of glucose utilization is fully restored following BMI normalization after bariatric surgery. We investigated if this also pertains to insulin-induced effects on fatty acid handling. Forty-three women with obesity (OB) were investigated before and 2 years after Roux-en-Y gastric by-pass when BMI was <30 kg/m² (PO) and compared with 26 never obese women (NO). The Adipo-IR index was used as measure of insulin antilipolytic sensitivity. Changes (delta) in circulating glycerol and fatty acid levels during hyperinsulinemic euglycemic clamp represented the insulin maximum antilipolytic effect. Overall fatty acid utilization was reflected by delta fatty acids minus 3 × delta glycerol. Adipo-IR was higher in OB than in NO and PO (p < 0.0001), the latter two groups having similar values. Insulin lowered glycerol levels by about 70% in all groups, but delta glycerol was 30% larger in PO than in NO (p = 0.04). Delta adds and adds utilization were similar in all groups. We conclude that women with obesity, whose BMI is normalized after bariatric surgery, have improved maximum in vivo antilipolytic effect of insulin above expected in absolute but not relative terms as regards glycerol changes, while the handling of circulating fatty acids is changed to the normal state.

Human White Adipose Tissue Displays Selective Insulin Resistance in the Obese State

Selective hepatic insulin resistance is a feature of obesity and type 2 diabetes. Whether similar mechanisms operate in white adipose tissue (WAT) of those with obesity and to what extent these are normalized by weight loss are unknown. We determined insulin sensitivity by hyperinsulinemic euglycemic clamp and insulin response in subcutaneous WAT by RNA sequencing in 23 women with obesity before and 2 years after bariatric surgery. To control for effects of surgery, women postsurgery were matched to never-obese women. Multidimensional analyses of 138 samples allowed us to classify the effects of insulin into three distinct expression responses: a common set was present in all three groups and included genes encoding several lipid/cholesterol biosynthesis enzymes; a set of obesity-attenuated genes linked to tissue remodeling and protein translation was selectively regulated in the two nonobese states; and several postobesity-enriched genes encoding proteins involved in, for example, one-carbon metabolism were only responsive to insulin in the women who had lost weight. Altogether, human WAT displays a selective insulin response in the obese state, where most genes are normalized by weight loss. This comprehensive atlas provides insights into the transcriptional effects of insulin in WAT and may identify targets to improve insulin action.

The Effect of Laparoscopic Gastric Bypass Surgery on Insulin Resistance and Glycosylated Hemoglobin A1c: a 2-Year Follow-up Study

BACKGROUND

Bariatric surgery improves insulin sensitivity and secretion in patients with type 2 diabetes, but the effect on patients with prediabetes or even normal glucose tolerance deserves further consideration.

METHODS

Cohort study including patients operated with laparoscopic Roux-en-Y gastric bypass surgery (LRYGB) between November 2012 and June 2017 at the Örebro University Hospital (n = 813) with follow-up of 742 patients 2 years after surgery. Fasting insulin, glucose, glycosylated hemoglobin (HbA1c), and homeostatic model assessment of insulin resistance (HOMA-IR) were analyzed at baseline and 2 years after surgery for patients with overt type 2 diabetes, prediabetes, or non-diabetes.

RESULTS

Fasting insulin levels improved for all groups (diabetics baseline 25.5 mIU/L, IQR 17.5-38.0, 2 years 7.6 mIU/L, IQR 5.4-11.1, p < 0.001; prediabetics baseline 25.0 mIU/L, IQR 17.5-35.0, 2 years 6.7mIU/L, IQR 5.3-8.8, p < 0.001; non-diabetics baseline 20.0 mIU/L, IQR 14.0-30.0, 2 years 6.4 mIU/L, IQR 5.0-8.5, p < 0.001). HbA1c improved in all groups (diabetics baseline 56 mmol/mol, IQR 49-74 [7.3%, IQP 6.6-8.9], 2 years 38 mmol/mol, IQR 36-47 [5.6%, IQR 5.4-6.4], p < 0.001; prediabetics baseline 40 mmol/mol, IQR 39-42 [5.8%, IQR5.7-6.0], 2 years 36 mmol/mol, IQR 34-38 [5.5%, IQR 5.3-5.6], p < 0.001; non-diabetics baseline 35 mmol/mol, IQR 33-37 [5.4%, IQR 5.2-5.5]; 2 years 34 mmol/mol, IQR 31-36 [5.3%, IQR 5.0-5.4], p < 0.001). HOMA-IR improved in all groups (diabetics baseline 9.3 mmol/mol, IQR 5.4-12.9, 2 years 1.9 mmol/mol, IQR 1.4-2.7, p < 0.001; prediabetics baseline 7.0 mmol/mol, IQR 4.3-9.9, 2 years 1.6 mmol/mol, IQR 1.2-2.1, p < 0.001; non-diabetics 4.9 mmol/mol, IQR 3.4-7.3, 2 years 1.4 mmol/mol, IQR 1.1-1.9, p < 0.001).

CONCLUSION

Insulin homeostasis and glucometabolic control improve in all patients after LRYGB, not only in diabetics but also in prediabetics and non-diabetic obese patients, and this improvement is sustained 2 years after surgery.

Body composition and breast cancer risk and treatment: mechanisms and impact

PURPOSE

The purpose of this review is to clarify the association of body composition with breast cancer risk and treatment, including physiological mechanisms, and to elucidate strategies for overcoming unfavorable body composition changes that relate to breast cancer progression.

METHODS

We have summarized updated knowledge regarding the mechanism of the negative association of altered body composition with breast cancer risk and treatment. We also review strategies for reversing unfavorable body composition based on the latest clinical trial results.

RESULTS

Body composition changes in patients with breast cancer typically occur during menopause or as a result of chemotherapy or endocrine therapy. Dysfunction of visceral adipose tissue (VAT) in the setting of obesity underlies insulin resistance and chronic inflammation, which can lead to breast cancer development and progression. Insulin resistance and chronic inflammation are also observed in patients with breast cancer who have sarcopenia or sarcopenic obesity. Nutritional support and a personalized exercise program are the fundamental interventions for reversing unfavorable body composition. Other interventions that have been explored in specific situations include metformin, testosterone, emerging agents that directly target the adipocyte microenvironment, and bariatric surgery.

CONCLUSIONS

A better understanding of the biology of body composition phenotypes is key to determining the best intervention program for patients with breast cancer.

Long-term effect of bariatric surgery on body composition in patients with morbid obesity: A systematic review and meta-analysis

We performed a meta-analysis to provide quantitative estimates of fat mass (FM) and fat-free mass (FFM) changes in patients following bariatric surgery over 1 year. A systematic search of PubMed, SCOPUS and Web of Science databases was conducted; the pooled weighted mean difference (WMD) and 95% confidence intervals (CI) were calculated using a random-effects model. Thirty-four studies including Roux en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) biliopancreatic diversion (BPD) and gastric banding (GB) were analyzed. RYGB decreased in body FM (-28.99 kg [31.21, -26.77]) or FM% (-12.73% [-15.14, -10.32]) or FFM (-9.97 kg [-10.93, -9.03]), which were greater than SG and GB. Moreover, the FFM% in RYGB group (11.72% [7.33, 16.11]) was more than SG (5.7% [4.44, 6.95]) and GB (8.1% [6.15, 10.05]) groups. Bariatric surgeries, especially RYGB, might be effective for a decrease in FM and maintenance of FFM in patients with morbid obesity in over 1 year.

Long-term changes in adipose tissue gene expression following bariatric surgery

OBJECTIVE

Patients undergoing bariatric surgery present long-term metabolic improvements and reduced type 2 diabetes risk, despite long-term weight regain. We hypothesized that part of these protective effects could be linked to altered gene expression in white adipose tissue (WAT).

METHODS

Transcriptomic profiling by gene microarray was performed in abdominal subcutaneous WAT from women before (n = 50) and two (n = 49) and five (n = 38) years after Roux-en-Y gastric bypass (RYGB) surgery as well as in 28 age-matched nonoperated women.

RESULTS

In the obese women, the average body weight decrease was 38 kg 2 years postsurgery followed by an 8 kg weight regain between 2 and 5 years. Most of the long-term changes in WAT gene expression occurred during the first 2 years. However, a subset of genes encoding proteins involved in inflammation displayed a continued decrease between baseline, 2 and 5 years, respectively; that is an expression pattern independent of body weight regain. Expression of 71 of these genes correlated with measurements of adipocyte morphology or serum adipokine levels.

CONCLUSION

The continuous improvement in WAT inflammatory gene expression, despite body weight relapse, may contribute to the sustained effects on adipose morphology after bariatric surgery.

Insulin resistance in bariatric surgery

PURPOSE OF REVIEW

To give an updated review on the underlying mechanisms and clinical effects of improved glucose control after bariatric surgery.

RECENT FINDINGS

The basic principles of the mechanism for the metabolic effects of bariatric surgery can be categorized into calorie restriction, deviation of nutrients, and reduced amounts of adipose tissue. Recent findings suggest the importance of early changes following deviation of nutrients to more distal parts of the small bowel resulting in altered release of gastrointestinal hormones, altered gut microbiota, and weight-reduction. In the long-term, loss of adipose tissue results in reduced inflammation and improved insulin sensitivity. From a clinical perspective these changes are associated with remission of diabetes in patients with morbid obesity and type 2 diabetes, prevention of diabetes in patients with insulin resistance without overt type 2 diabetes and prevention of both microvascular and macrovascular complications for all patients with morbid obesity.

SUMMARY

At present, bariatric surgery remains the most effective treatment option to improve glucose control and long-term complications associated with hyperglycemia in patients with obesity.Although the mechanisms behind these metabolic effects remain only partially understood, further knowledge on these complex mechanisms may help identifying durable treatment options for morbid obesity and important metabolic comorbidities.

Genome-Wide Association Study of Diabetogenic Adipose Morphology in the GENetics of Adipocyte Lipolysis (GENiAL) Cohort

An increased adipocyte size relative to the size of fat depots, also denoted hypertrophic adipose morphology, is a strong risk factor for the future development of insulin resistance and type 2 diabetes. The regulation of adipose morphology is poorly understood. We set out to identify genetic loci associated with adipose morphology and functionally evaluate candidate genes for impact on adipocyte development. We performed a genome-wide association study (GWAS) in the unique GENetics of Adipocyte Lipolysis (GENiAL) cohort comprising 948 participants who have undergone abdominal subcutaneous adipose biopsy with a determination of average adipose volume and morphology. The GWAS identified 31 genetic loci displaying suggestive association with adipose morphology. Functional evaluation of candidate genes by small interfering RNAs (siRNA)-mediated knockdown in adipose-derived precursor cells identified six genes controlling adipocyte renewal and differentiation, and thus of potential importance for adipose hypertrophy. In conclusion, genetic and functional studies implicate a regulatory role for ATL2, ARHGEF10, CYP1B1, TMEM200A, C17orf51, and L3MBTL3 in adipose morphology by their impact on adipogenesis.

Metabolic Impact of Body Fat Percentage Independent of Body Mass Index in Women with Obesity Remission After Gastric Bypass

BACKGROUND/OBJECTIVE

Body mass index (BMI) is central when evaluating treatment effect after gastric bypass. The metabolic impact of BMI-independent differences in body fat percentage (BF%) after gastric bypass is not fully understood. We compared metabolic and adipose tissue characteristics in women with high versus low BF% independent of BMI after obesity remission following gastric bypass.

SUBJECTS/METHODS

A cohort of 215 women was included at baseline. A total of 166 women were re-examined 2 years after gastric bypass, whereof 130 had obesity remission (BMI < 30 kg/m2). Anthropometric parameters, blood pressure, and lipids were measured. Total and regional body fat mass was determined by dual-energy X-ray absorptiometry. Insulin sensitivity was assessed by homeostasis model assessment of insulin resistance (HOMA-IR) and hyperinsulinemic euglycemic clamp (M value). Adipocyte size and number were determined.

RESULTS

Of the 130 women with obesity remission, 64 had BF% ≥ 35 and 65 < 35. Independent of BMI, high BF% were associated with higher HOMA-IR (P = 0.021), lower M value (P = 0.0046), higher triglycerides (P = 0.013), higher visceral/total and android/gynoid fat mass ratios (P = 0.0032 and 0.0003 respectively), and larger subcutaneous fat cell volume (P < 0.0001) 2 years after gastric bypass. No differences in anthropometric measures, glucose, blood pressure, or fat cell number were observed.

CONCLUSIONS

Independent of BMI, patients with higher BF% displayed lower insulin sensitivity, higher triglyceride levels, central fat distribution, and larger subcutaneous adipocytes 2 years after gastric bypass. Thus, determination of BF% provides additional information of metabolic characteristics at follow-up of non-obese patients after gastric bypass.

Phosphatidylcholine and its relation to apolipoproteins A-1 and B changes after Roux-en-Y gastric bypass: a cohort study

Background

Phosphatidylcholine (PC), the most abundant of the phospholipids, has several metabolic functions in organs such as the liver and the intestine, important structural- and signaling functions in biological membranes, and might have a role in the effects of Roux-en-Y gastric bypass (RYGB), an operation known to ameliorate metabolic diseases, including type 2 diabetes. We hypothesized that serum PC, as a reflection of phospholipid metabolism, changes after RYGB, and that changes are related to weight loss and possibly to changes in glucose metabolism (reflected in the HbA1c-level) as well as to changes in serum Apo A1, Apo B and Apo B/Apo A1 ratio.

Methods

In a cohort of 220 RYGB patients, we studied changes in serum PC after RYGB in relation to serum Apo A1 and Apo B, the main apolipoproteins in HDL- and LDL/VLDL-particles, respectively, up to 2 years following RYGB-surgery.

Results

Serum PC reached its lowest levels 3 months postoperatively to later rebound to preoperative levels 24 months after RYGB. No difference was seen between patients with or without type 2 diabetes. Serum Apo A1 showed a similar pattern whereas serum Apo B concentrations stayed low after the initial decrease after RYGB. As a result, the Apo B / Apo A1 ratio constantly decreased during follow-up. There was a strong positive correlation between PC and Apo A1, and between PC and Apo B, but none between Apo A1 and Apo B. After RYGB surgery, both PC and Apo A1, but not Apo B, correlated positively to weight loss. In relation to total cholesterol, the molar ratio between serum PC and plasma cholesterol increased steadily after RYGB.

Conclusions

We conclude that changes in PC and apolipoproteins after RYGB are highly dynamic, reflecting a large plasticity and capability of accommodating lipid metabolism including PC-, cholesterol- and apolipoprotein metabolism imposed by RYGB surgery, independent of glucose tolerance. We suggest that after RYGB and major weight loss, PC and Apo A1 might have a special role in the altered metabolism of lipoproteins.

Electronic supplementary material

The online version of this article (10.1186/s12944-019-1111-7) contains supplementary material, which is available to authorized users.