A Systematic Review and Meta-analysis of the Effect of Gastric Bypass Surgery on Plasma Lipid Levels

The Effect of Diet Composition on the Post-operative Outcomes of Roux-en-Y Gastric Bypass in Mice

PURPOSE

Roux-en-Y gastric bypass (RYGB) leads to the improvement of many obesity-associated conditions. The degree to which post-operative macronutrient composition contributes to metabolic improvement after RYGB is understudied.

METHODS

A mouse model of RYGB was used to examine the effects of diet on the post-operative outcomes of RYGB. Obese mice underwent either Sham or RYGB surgery and were administered either chow or HFD and then monitored for an additional 8 weeks.

RESULTS

After RYGB, reductions to body weight, fat mass, and lean mass were similar regardless of diet. RYGB and HFD were independently detrimental to bone mineral density and plasma vitamin D levels. Independent of surgery, HFD accelerated hematopoietic stem and progenitor cell proliferation and differentiation and exhibited greater myeloid lineage commitment. Independent of diet, systemic iron deficiency was present after RYGB. In both Sham and RYGB groups, HFD increased energy expenditure. RYGB increased fecal energy loss, and HFD after RYGB increased fecal lipid content. RYGB lowered fasting glucose and liver glycogen levels but HFD had an opposing effect. Indices of insulin sensitivity improved independent of diet. HFD impaired improvements to dyslipidemia, NAFLD, and fibrosis.

CONCLUSION

Post-operative diet plays a significant role in determining the degree to which RYGB reverses obesity-induced metabolic abnormalities such as hyperglycemia, dyslipidemia, and NAFLD. Diet composition may be targeted in order to assist in the treatment of post-RYGB bone mineral density loss and vitamin D deficiency as well as to reverse myeloid lineage commitment. HFD after RYGB continues to pose a significant multidimensional health risk.

Systematic Review and Meta-analysis of the Effects of Laparoscopic Roux-en-Y Gastric Bypass and Laparoscopic Sleeve Gastrectomy on Dyslipidemia

The aim of this meta-analysis was to compare the effects of LRYGB and LSG on dyslipidemia. Studies comparing the effects of LRYGB and LSG on dyslipidemia with follow-up of 12 months or more were included. Twenty-four studies comprising seven RCTs and 17 comparative observational studies were included. Meta-analysis of RCTs (n=487) showed that improvement/resolution of dyslipidemia was better after LRYGB (68.5%, n=161/235) compared to LSG (48.4%, n=122/252). Patients undergoing LRYGB were more than twice as likely to experience improvement/resolution in dyslipidemia compared to those undergoing LSG (OR 2.28, 95% CI 1.21-4.29, p=0.010). Both LRGYB and LSG appears effective in improving dyslipidemia at >12 months after surgery; however, this improvement is more than twice higher after LRYGB compared to LSG.

Excess body weight: Novel insights into its roles in obesity comorbidities

Excess body weight is a global health problem due to sedentary lifestyle and unhealthy diet, affecting 2 billion population worldwide. Obesity is a major risk factor for metabolic diseases. Notably, the metabolic risk of obesity largely depends on body weight distribution, of which visceral adipose tissues but not subcutaneous fats are closely associated with obesity comorbidities, including type 2 diabetes, non-alcoholic fatty liver disease, cardiovascular disease and certain types of cancer. Latest multi-omics and mechanistical studies reported the crucial involvement of genetic and epigenetic alterations, adipokines dysregulation, immunity changes, imbalance of white and brown adipose tissues, and gut microbial dysbiosis in mediating the pathogenic association between visceral adipose tissues and comorbidities. In this review, we explore the epidemiology of excess body weight and the up-to-date mechanism of how excess body weight and obesity lead to chronic complications. We also examine the utilization of visceral fat measurement as an accurate clinical parameter for risk assessment in healthy individuals and clinical outcome prediction in obese subjects. In addition, current approaches for the prevention and treatment of excess body weight and its related metabolic comorbidities are further discussed. DATA AVAILABILITY: No data was used for the research described in the article.

Effects of Roux-en-Y gastric bypass on the metabolic profile and systemic inflammatory status of women with metabolic syndrome: randomized controlled clinical trial

BACKGROUND

Obesity remains a public health problem worldwide. The high prevalence of this condition in the population raises further concerns, considering that comorbidities are often associated with obesity. Among the comorbidities closely associated with obesity, metabolic syndrome (MS) is particularly important, which potentially increases the risk of manifestation of other disorders, such as the prothrombotic and systemic pro-inflammatory states.

METHODS

A randomized, controlled clinical trial was performed involving female patients (n = 32) aged between 18 and 65 years, with a clinical diagnosis of MS, with severe obesity undergoing Roux-en-Y gastric bypass (RYGB). The study design followed the Consolidated Standards of Reporting Trials statement (CONSORT). Lipid profile, blood glucose and adipokines (adiponectin, leptin, and resistin) and (cytokines IL-1β, IL-6, IL-17, IL-23, and TNF-α) in blood plasma samples were evaluated before and six months after RYGB.

RESULTS

Patients undergoing RYGB (BSG) showed a significant improvement from preoperative grade III obesity to postoperative grade I obesity. The results showed that while HDL levels increased, the other parameters showed a significant reduction in their postoperative values when compared not only to the values observed before surgery in the BSG group, but also to the values obtained in the control group (CG). As for systemic inflammatory markers adiponectin, leptin, resistin, IL-1β, IL-6, IL-17, IL-23 and TNF- α it was observed that the levels of resistin and IL-17 in the second evaluation increased significantly when compared to the levels observed in the first evaluation in the CG. In the BSG group, while the levels of adiponectin increased, the levels of the other markers showed significant reductions in the postoperative period, in relation to the respective preoperative levels. The analysis of Spearman's correlation coefficient showed a significant positive correlation between IL-17 and IL-23 in the preoperative period, significant positive correlations between TNF-α and IL-6, TNF-α and IL-17, IL-6 and IL-17, and IL-17 and IL-23 were observed postoperatively.

CONCLUSIONS

According to our results, the reduction of anthropometric measurements induced by RYGB, significantly improves not only the plasma biochemical parameters (lipid profile and glycemia), but also the systemic inflammatory status of severely obese patients with MS. Trials registration NCT02409160.

Changes in plasma free fatty acids in obese patients before and after bariatric surgery highlight alterations in lipid metabolism

Obesity is a complex disease that increases an individual’s risk of developing other diseases and health-related problems. A common feature is dyslipidemia characterized by increased levels of plasma lipids, which include non-esterified fatty acids (NEFAs). The role of NEFAs in obesity-related morbidity is interesting as NEFAs constitute a reservoir of metabolic energy, are principal components of cell membranes and are precursors for signalling molecules. Bariatric surgery promotes sustained weight loss in severely obese patients, reducing the incidence and severity of co-morbidities. In this study we measure changes in circulating NEFA species in plasma samples taken from 25 obese individuals before and 9 months after Roux-en-Y gastric bypass surgery. The mean weight of the cohort reduced by 29.2% from 149.0 ± 25.1 kg pre-surgery to 105.5 ± 19.8 kg post-surgery and the BMI by 28.2% from 51.8 ± 6.3 kg/m² pre-surgery to 37.2 ± 5.4 kg/m². Mean glycated haemoglobin (HbA1c) reduced from 6.5 ± 1.3 to 5.5 ± 0.5%, consistent with the intervention leading to improved glycaemic control, particularly in those who were dysglycemic prior to surgery. Total and LDL cholesterol concentrations were markedly reduced following surgery. Concentrations of seven NEFAs were found to decrease 9 months after surgery compared to pre-surgery levels: myristate, palmitoleate, palmitate, linoleate, oleate, stearate and arachidonate. Bariatric surgery led to increased lipogenesis and elongase activity and decreased stearoyl-CoA desaturase 1 activity. This study therefore highlights metabolic changes that take place following gastric bypass surgery in severely obese patients.

The Effect of Bariatric Surgery on Circulating Levels of Lipoprotein (a): A Meta-analysis

Background

Obesity, especially severe obesity, is associated with a higher risk of atherosclerotic cardiovascular disease (ASCVD) morbidity and mortality. Bariatric surgery is a durable and effective weight loss therapy for patients with severe obesity and weight-related comorbidities. Elevated plasma levels of lipoprotein (a) (Lp(a)) are causally associated with ASCVD. The aim of this meta-analysis was to analyze whether bariatric surgery is associated with Lp(a) concentrations.

Methods

A literature search in PubMed, Scopus, Embase, and Web of Science was performed from inception to May 1st, 2021. A random-effects model and the generic inverse variance weighting method were used to compensate for the heterogeneity of studies in terms of study design, treatment duration, and the characteristics of the studied populations. A random-effects metaregression model was used to explore the association with an estimated effect size. Evaluation of funnel plot, Begg's rank correlation, and Egger's weighted regression tests were used to assess the presence of publication bias in the meta-analysis.

Results

Meta-analysis of 13 studies including 1551 patients showed a significant decrease of circulating Lp(a) after bariatric surgery (SMD: -0.438, 95% CI: -0.702, -0.174, p < 0.001, I²: 94.05%). The results of the metaregression did not indicate any significant association between the changes in Lp(a) and duration of follow-up after surgery, reduction in body mass index, or baseline Lp(a) concentration. The reduction in circulating Lp(a) was robust in the leave-one-out sensitivity analysis.

Conclusion

Bariatric surgery significantly decreases circulating Lp(a) concentrations. This decrease may have a positive effect on ASCVD in obese patients.

Early effects of Roux-en-Y gastric bypass on dietary fatty acid absorption and metabolism in people with obesity and normal glucose tolerance

INTRODUCTION

Roux-en-Y gastric bypass (RYGB) surgery markedly increases the rate of intestinal nutrient exposure after food intake, accelerates intestinal absorption of dietary glucose and protein, and alters the postprandial gut hormone response. However, our understanding of postprandial fat absorption and metabolism after RYGB is incomplete.

METHODS

Stable palmitate tracers were administered intravenously (K-[2,2-²H₂]palmitate) and orally with a mixed meal ([U-¹³C₁₆]palmitate) to study fatty acid absorption and metabolism before and 3 months after RYGB in 10 participants with obesity and normal glucose tolerance.

RESULTS

There was a tendency toward reduced fasting plasma nonesterified palmitate concentrations after RYGB, but neither fasting palmitate kinetics nor fasting triacylglycerol (TAG) concentrations changed compared with before surgery. Postprandial TAG concentrations were numerically, but nonsignificantly, reduced 3-4 h after meal intake after compared with before RYGB. However, the postprandial appearance of the oral palmitate tracer in the plasma TAG pool and overflow into the nonesterified palmitate pool were initially faster but overall reduced after RYGB by 50% (median, IQR: [47;64], P = 0.004) and 46% (median, IQR: [33;70], P = 0.041), respectively. The maximal postprandial suppression of plasma nonesterified palmitate concentrations was slightly greater but shorter lasting after RYGB ('time × visit' interaction: P < 0.001), without detectable effects of surgery on the rate of appearance and disappearance of plasma palmitate.

CONCLUSION

RYGB resulted in an initially accelerated but overall ~50% reduced 4-h postprandial systemic appearance of dietary palmitate in participants with obesity and normal glucose tolerance. This is likely a result of faster but incomplete intestinal fat absorption combined with enhanced chylomicron-TAG clearance, but it needs further investigation in studies specifically designed to investigate these mechanisms.

Can exercise promote additional benefits on body composition in patients with obesity after bariatric surgery? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Bariatric surgery is the most effective treatment for patients with severe obesity, but success rates vary substantially. Exercise is recommended after bariatric surgery to reduce weight regain but the effectiveness remains undetermined on weight loss due to conflicting results. It is also unclear what should be the optimal exercise prescription for these patients. A systematic review and meta-analysis of randomized controlled trials on the effects of exercise on body weight (BW), anthropometric measures, and body composition after bariatric surgery was performed.

METHODS

PubMed/MEDLINE®, EBSCO®, Web of Science® and Scopus® databases were searched to identify studies evaluating exercise effectiveness.

RESULTS

The analysis comprised 10 studies (n = 487 participants). Exercise favored BW (-2.51kg; p = 0.02), waist circumference (-4.14cm; p = 0.04) and body mass index (-0.84kg·m-2; p = 0.02) reduction but no improvements in body composition. Combined exercise interventions were the most effective in reducing BW (-5.50kg; p < 0.01) and body mass index (-1.86kg·m-2; p < 0.01). Interventions starting >6-months after bariatric surgery were more successful in reducing BW (-5.02kg; p < 0.01) and body mass index (-1.62kg·m-2; p < 0.01).

CONCLUSION

Exercise, combined exercise regimens and interventions starting >6-months after bariatric surgery were effective in promoting BW, waist circumference and body mass index reduction. Exercise following bariatric surgery does not seem to favor body composition improvements.

Ten year comparative analysis of sleeve gastrectomy, Roux-en-Y gastric bypass, and biliopancreatic diversion with duodenal switch in patients with BMI ≥ 50 kg/m2

INTRODUCTION

Bariatric surgery is the most effective modality to stably reduce weight and related comorbidities in patients suffering from class II and III obesity. Data comparing long-term safety and efficacy of the three most effective bariatric operations are limited in patients with BMI ≥ 50 kg/m², which complicate shared surgeon-patient decision making regarding optimal procedure selection.

METHODS

A retrospective analysis was performed on all patients with BMI ≥ 50 kg/m² who underwent biliopancreatic diversion with duodenal switch (BPD/DS), Roux-en-Y gastric bypass (RYGB), or sleeve gastrectomy (SG) at our institution between 2009 and 2019. Data collected from patients' electronic medical records included operative details as well as BMI and presence and resolution of obesity-related comorbidities at 0, 6, 12, 24, 48, and 60 months post-operatively.

RESULTS

Among 537 patients with BMI ≥ 50 kg/m² who had a primary bariatric procedure, 93 patients underwent BPD/DS (17.3%), 341 patients underwent RYGB (63.5%), and 103 patients underwent SG (19.2%). BMI decreased by 23.7 kg/m² in BPD/DS, 14.7 kg/m² in RYGB, and 13.6 kg/m² in SG cohorts at 60 months post-operatively (p < 0.0001). The greatest %TWL occurred in BPD/DS cohort (38.4%) followed by the RYGB (26.3%) and SG (23.6%) cohorts (p < 0.0001). The thirty-day complication rate was 12.9% for BPD/DS, 4.7% for RYGB, and 8.7% for SG (p = 0.015).

CONCLUSIONS

Our study demonstrated that the BPD/DS is the most effective operation at long-term reduction of BMI and achieved highest %TWL while SG and RYGB had similar results at 60 months post-op. BPD/DS is associated with increased early and late surgical complications compared to RYGB and SG.

The effect of bariatric surgery on ischemic stroke risk

BACKGROUND

Metabolic and bariatric surgery (MBS) has demonstrated improvements in diabetes and cardiovascular health. The effect of MBS on the risk of ischemic stroke remains unclear.

OBJECTIVES

The goal of this study was to determine the risk of stroke following MBS compared with patients with obesity who qualified for but did not undergo MBS.

SETTING

The Mariner Database, a national claims database.

METHODS

We identified patients with body mass index (BMI) ≥40 or those with a BMI and a qualifying co-morbidity, who underwent MBS between 2010 to 2019. Similar patients who did not undergo MBS served as controls. Coarsened exact matching was performed followed by logistic regression analysis to determine the effect of BMS on stroke risk.

RESULTS

A total of 70 622 BMS patients and 1 320 182 MBS-eligible controls were identified. After matching, the 1-year stroke risk among MBS patients (n = 56 514) versus controls (n = 56 514) was .6% versus 1.2% (OR .54, 95% CI .47-.61). The 5-year stroke risk for MBS (n = 27619) versus control (n = 27619) was 2.8% versus 3.6% (OR .78, 95% CI .65-.90).

CONCLUSION

MBS appears to reduce the risk of stroke following surgery. To our knowledge, this is the largest sample size in a study of ischemic cerebrovascular disease in bariatric surgery.

Improvement of Lipid Profile after One-Anastomosis Gastric Bypass Compared to Sleeve Gastrectomy

Fewer studies compared the improvement of plasma lipid levels after different types of surgery, in particular compared to one-anastomosis gastric bypass (OAGB). The aim of our study was to investigate how laparoscopic sleeve gastrectomy (LSG) and OAGB impact on weight loss and lipid profile 18 months after surgery, in patients with severe obesity. Forty-six patients treated with OAGB were matched to eighty-eight patients submitted to LSG. Weight loss after OAGB (33.2%) was more evident than after LSG (29.6%) (p = 0.024). The difference in the prevalence of dyslipidemia showed a statistically significant reduction only after OAGB (61% versus 22%, p < 0.001). After adjustment for delta body mass index (BMI), age and sex, we demonstrated a statistically significant decrease of the differences between the changes before and after (delta Δ) the two surgery procedures: Δ total cholesterol values (p < 0.001), Δ low density lipoprotein-cholesterol values (p < 0.001) and Δ triglycerides values (p = 0.007). Patients with severe obesity undergoing to OAGB presented a better improvement of lipid plasma values than LSG patients. The reduction of lipid plasma levels was independent of the significant decrease of BMI after surgery, of age and of sex.

Pregnancy and lactation after Roux-en-Y gastric bypass worsen nonalcoholic fatty liver disease in obese rats and lead to differential programming of hepatic de novo lipogenesis in offspring

Maternal obesity increases the risk of nonalcoholic fatty liver disease (NAFLD) in offspring. The Roux-en-Y gastric bypass (RYBG) is effective for achieving weight loss and ameliorates NAFLD. To determine whether these benefits are maintained after pregnancy and/or lactation, and whether they modulate hepatic morphofunction in the next generation, we evaluated hepatic lipid metabolism in Western diet (WD)-obese female rats that underwent RYGB and in their F1 offspring at adulthood. Female Wistar rats consumed a WD from 21 to 130 days of age, before being submitted to RYGB (WD-RYGB-F0) or SHAM (WD-SHAM-F0) operations. After 5 weeks, these females were mated with control male breeders, and the male and female F1 offspring were identified as WD-RYGB-F1 and WD-SHAM-F1. WD-RYGB-F0 dams exhibited lower serum lipids levels, but severe hepatic steatosis and pathological features of advanced liver injury. The hepatic proteins involved in lipogenesis were reduced in WD-RYGB-F0, as were the genes related to β-oxidation and bile acids (BAs). Although the female and male WD-RYGB-F1 groups did not exhibit hepatic steatosis, the livers of female WD-RYGB-F1 demonstrated higher amounts of lipogenic genes and proteins, while male WD-RYGB-F1 presented a similar downregulation of lipogenic factors to that seen in WD-RYGB-F0 dams. In contrast, maternal and offspring groups of both sexes displayed reductions in the expressions of genes involved in BAs physiology and gluconeogenesis. As such, RYGB aggravates NAFLD after pregnancy and lactation and induces a gender-dependent differential expression of the hepatic lipogenesis pathway in offspring, indicating that female WD-RYGB-F1 may be an increased risk of developing NAFLD.

Improvement of glucose metabolism following rapid weight loss after bariatric surgery and its impact on reduction of visceral abdominal fat versus free fat muscle

BACKGROUND

Body fat distribution is highly associated with metabolic disturbances. Skeletal muscle plays an important role in glucose metabolism, as it serves as an important organ for glucose storage in the form of glycogen. In fact, low muscle mass has been associated with metabolic syndrome, type 2 diabetes (T2D), systemic inflammation, and decreased survival.

OBJECTIVES

To compare the relationship between visceral abdominal fat (VAF) and fat free mass (FFM) with the improved glucose metabolism after bariatric surgery.

SETTING

University hospital, United States.

METHODS

A retrospective review was performed of all patients who underwent bariatric surgery between 2011 and 2017 at a university hospital in the United States. In severely obese patients with T2D, we measured the VAF via abdominal computed tomography scan and we calculated the FFM preoperatively and at a 12-month follow-up. Data collected included baseline demographic characteristics and perioperative parameters, such as treatment for hypertension (HTN) and T2D, body mass index (BMI), glycated hemoglobin (HbA1C), glucose, and lipid profile.

RESULTS

A total of 25 patients met the inclusion criteria. The average age was 52.5 ± 11.6 years. The initial BMI was 41.41 ± 5.7 kg/m² and the postoperative BMI was 31.7 ± 6.9 kg/m² (P < .0001). The preoperative VAF volume was 184.6 ± 90.2 cm³ and the postoperative VAF volume was 93.8 ± 46.8 cm³ at the 12-month follow-up (P < .0001). The preoperative FFM was 55.2 ± 11.4 kg and the postoperative FFM was 49.1 ± 12 kg (P < .072). The preoperative HbA1C was 5.8% ± .9%, which decreased postoperatively to 5.3% ± .4% at the 12-month follow-up (P < .013).

CONCLUSION

Bariatric surgery has been demonstrated to be an effective treatment modality for severe obesity and T2D. Our results suggest that at 12 months, there is a reduction in VAF and HbA1C without a significant loss of FFM. Further prospective studies are needed to better understand these findings.

Fractionated free fatty acids and their relation to diabetes status after Roux-en-Y gastric bypass: A cohort study

Bariatric surgery is associated with near-immediate remission of type 2 diabetes and recently suggested as a treatment for type 2 diabetes. Specifically, Roux-en-Y gastric bypass has been a focus of much research, but still, the mechanisms of action are only partly elucidated. We aim to investigate whether some mechanisms might be mediated by free fatty acids (FFAs). We measured eight fractionated FFAs before and up to 2 years after Roux-en-Y gastric bypass surgery in 207 patients, divided into three groups. One non-diabetic group, one diabetic group with post-operative remission and one diabetic group with persistent diabetes after surgery. Pre- and postoperative levels of fractionated FFAs were compared within and between groups. The sum of the measured FFAs were lower in the group with persistent diabetes, compared to the other groups. The pre-surgery level of linoleic acid in the group with persistent diabetes was significantly lower compared to the other two groups. The levels of fractionated FFAs decreased from pre-surgery to three months after surgery, except for oleic acid and arachidonic acid and for Docosahexaenoic acid (DHA) in the non-diabetic group. The FFAs with decreasing levels from pre-surgery to three months post-surgery are all precursors to oleic acid, arachidonic acid, and DHA, respectively, which may imply a drift, indicating that they need to be sustained at an acceptable level for optimal metabolic function. The fact that the sum of the measured FFAs is lower in the group with persistent diabetes may suggest that this group and the group with diabetes remission represent two distinct types of type 2 diabetes. It is proposed that linoleic acid could be used as a biomarker to determine the plausibility for type 2 diabetes remission after Roux-en-Y gastric bypass surgery.

Effect of one-anastomosis gastric bypass on cardiovascular risk factors in patients with vitamin D deficiency and morbid obesity: A secondary analysis

BACKGROUND AND AIMS

Bariatric patients often suffer from vitamin D (VD) deficiency, and both, morbid obesity and VD deficiency, are related to an adverse effect on cardiovascular disease (CVD) risk. Therefore, we assessed the change of known CVD risk factors and its associations during the first 12 months following one-anastomosis gastric bypass (OAGB).

METHODS AND RESULTS

In this secondary analysis, CVD risk factors, medical history and anthropometric data were assessed in fifty VD deficient (25-hydroxy-vitamin D (25(OH)D) <75 nmol/l) patients, recruited for a randomized controlled trial of VD supplementation. Based on previous results regarding bone-mass loss and the association between VD and CVD risk, the study population was divided into patients with 25(OH)D ≥50 nmol/l (adequate VD group; AVD) and into those <50 nmol/l (inadequate VD group; IVD) at 6 and 12 months (T6/12) postoperatively. In the whole cohort, substantial remission rates for hypertension (38%), diabetes (30%), and dyslipidaemia (41%) and a significant reduction in CVD risk factors were observed at T12. Changes of insulin resistance markers were associated with changes of total body fat mass (TBF%), 25(OH)D, and ferritin. Moreover, significant differences in insulin resistance markers between AVD and IVD became evident at T12.

CONCLUSION

These findings show that OAGB leads to a significant reduction in CVD risk factors and amelioration of insulin resistance markers, which might be connected to reduced TBF%, change in 25(OH)D and ferritin levels, as an indicator for subclinical inflammation, and an adequate VD status. REGISTERED AT CLINICALTRIALS.GOV: (Identifier: NCT02092376) and EudraCT (Identifier: 2013-003546-16).

Sample Preparation Methods for Lipidomics Approaches Used in Studies of Obesity

Obesity is associated with alterations in the composition and amounts of lipids. Lipids have over 1.7 million representatives. Most lipid groups differ in composition, properties and chemical structure. These small molecules control various metabolic pathways, determine the metabolism of other compounds and are substrates for the syntheses of different derivatives. Recently, lipidomics has become an important branch of medical/clinical sciences similar to proteomics and genomics. Due to the much higher lipid accumulation in obese patients and many alterations in the compositions of various groups of lipids, the methods used for sample preparations for lipidomic studies of samples from obese subjects sometimes have to be modified. Appropriate sample preparation methods allow for the identification of a wide range of analytes by advanced analytical methods, including mass spectrometry. This is especially the case in studies with obese subjects, as the amounts of some lipids are much higher, others are present in trace amounts, and obese subjects have some specific alterations of the lipid profile. As a result, it is best to use a method previously tested on samples from obese subjects. However, most of these methods can be also used in healthy, nonobese subjects or patients with other dyslipidemias. This review is an overview of sample preparation methods for analysis as one of the major critical steps in the overall analytical procedure.

The Effect of Bariatric Surgery on Weight Loss and Metabolic Changes in Adults with Obesity

Methods of treating obesity, such as changes in lifestyle, physical activity, restrictive diets, and psychotherapy, are not sufficient. Currently, it is considered that in the case of patients who meet the eligibility criteria for surgery, the treatment of choice should be bariatric surgery. The aim of this study was to assess the weight loss and metabolic changes in a group of adults with obesity undergoing bariatric surgery. The study involved 163 patients whose body mass index (BMI) exceeded 40 or 35 kg/m², concurrent with at least one metabolic sequelae. In 120 of the cases (74%), sleeve gastrectomy was used; in 35 (21%), gastric banding was used; and in 8 (5%), laparoscopic Roux-en-Y gastric bypass was used. Metabolic parameters such as total cholesterol, LDL-cholesterol (low-density lipoprotein cholesterol), HDL-cholesterol (high-density lipoprotein cholesterol), triglycerides, and glucose were measured preoperatively and postoperatively, as well as the creatinine, creatine kinase (CK-MB), and leptin activity. In patients undergoing bariatric surgery, a significant decrease in excess weight (p < 0.001) was observed at all the analyzed time points, compared to the pre-surgery value. Weight loss after surgery was associated with a significant improvement in glycemia (109.6 ± 48.0 vs. 86.6 ± 7.9 mg/dL >24 months after surgery; p = 0.003), triglycerides (156.9 ± 79.6 vs. 112.7 ± 44.3 mg/dL >24 months after surgery; p = 0.043) and leptin (197.50 ± 257.3 vs. 75.98 ± 117.7 pg/mL 12 months after surgery; p = 0.0116) concentration. The results of the research confirm the thesis on the effectiveness of bariatric surgery in reducing excess body weight and improving metabolic parameters in patients with extreme obesity.

Fecal metagenomics and metabolomics reveal gut microbial changes after bariatric surgery

BACKGROUND

Evidence from longitudinal patient studies regarding gut microbial changes after bariatric surgery is limited.

OBJECTIVE

To examine intraindividual changes in fecal microbiome and metabolites among patients undergoing Roux-en-Y gastric bypass or vertical sleeve gastrectomy.

SETTING

Observational study.

METHODS

Twenty patients were enrolled and provided stool samples before and 1 week, 1 month, and/or 3 months after surgery. Shallow shotgun metagenomics and untargeted fecal metabolomics were performed. Zero-inflated generalized additive models and linear mixed models were applied to identify fecal microbiome and metabolites changes, with adjustment for potential confounders and correction for multiple testing.

RESULTS

We enrolled 16 women and 4 men, including 16 white and 4 black participants (median age = 45 years; presurgery body mass index = 47.7 kg/m²). Ten patients had Roux-en-Y gastric bypass, 10 had vertical sleeve gastrectomy, and 14 patients provided postsurgery stool samples. Of 47 samples, median sequencing depth was 6.3 million reads and 1073 metabolites were identified. Microbiome alpha-diversity increased after surgery, especially at 3 months. Significant genus-level changes included increases in Odoribacter, Streptococcus, Anaerotruncus, Alistipes, Klebsiella, and Bifidobacterium, while decreases in Bacteroides, Coprocosccus, Dorea, and Faecalibacterium. Large increases in Streptococcus, Akkermansia, and Prevotella were observed at 3 months. Beta-diversity and fecal metabolites were also changed, including reduced caffeine metabolites, indoles, and butyrate.

CONCLUSIONS

Despite small sample size and missing repeated samples in some participants, our pilot study showed significant postsurgery changes in fecal microbiome and metabolites among bariatric surgery patients. Future large-scale, longitudinal studies are warranted to investigate gut microbial changes and their associations with metabolic outcomes after bariatric surgery.

Roux-en-Y gastric bypass, but not sleeve gastrectomy, decreases plasma PCSK9 levels in morbidly obese patients

AIM

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a master regulator of low-density lipoprotein cholesterol (LDL-C) metabolism, acting as an endogenous inhibitor of the LDL receptor. While it has been shown that bariatric surgery differentially affects plasma LDL-C levels, little is known of its effects on plasma PCSK9 concentrations. Therefore, the present study aimed to: (i) investigate the effect of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) on plasma PCSK9 concentrations; and (ii) correlate baseline or postoperative plasma PCSK9 concentration variations with anthropometric and metabolic parameters.

METHODS

Fasting plasma PCSK9 levels were measured by ELISA in morbidly obese patients before and 6 months after bariatric surgery. Patients were recruited from three prospective cohorts (in Nantes and Colombes in France, and Antwerp in Belgium).

RESULTS

A total of 156 patients (34SG, 122RYGB) were included. Plasma PCSK9, LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C) levels were significantly reduced after RYGB (-19.6%, -16.6% and -19.5%, respectively; P<0.0001), but not after SG. In all patients, postoperative PCSK9 change was positively correlated with fasting plasma glucose (FPG; r=0.22, P=0.007), HOMA-IR (r=0.24, P=0.005), total cholesterol (r=0.17, P=0.037) and non-HDL-C (r=0.17, P=0.038) variations, but not LDL-C. In contrast to what was observed for glucose parameters (FPG, HOMA-IR), correlation between PCSK9 and non-HDL-C changes after RYGB was independent of total weight loss.

CONCLUSION

RYGB, but not SG, promotes a significant reduction in plasma PCSK9 levels, and such changes in circulating PCSK9 levels after RYGB appear to be more associated with glucose improvement than with lipid homoeostasis parameters.

Morbid obesity and dyslipidaemia: The impact of bariatric surgery

Obesity prevalence has presented an exponential increase in the last decades, becoming a first order public health issue. Dyslipidemia of obesity, characterized by low levels of high density lipoprotein (HDL) cholesterol, hypertriglyceridemia and small and dense low-density lipoprotein (LDL) particles, is partly responsible for the high residual cardiovascular risk of this clinical situation. On the other hand, bariatric surgery (BS) is the most effective treatment for obesity, obtaining a greater weight loss than achieved with conventional medical therapy and favoring the improvement or remission of associated comorbidities. The most commonly used BS techniques nowadays are laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG). Both of these procedures have obtained similar results in terms of weight loss and comorbidity remission such as type2 diabetes mellitus or hypertension. A differential feature between both techniques could be the different impact on the lipoprotein profile. In this respect, previous studies with short and mid-term follow-up have proved LRYGB to be superior to LSG in total and LDL cholesterol reduction. Results regarding triglycerides and HDL cholesterol are contradictory. Therefore, we consider of interest to review the effects of BS at short and mid-term follow-up on lipoprotein profile, as well as the remission rates of the different lipid abnormalities and the possible related factors.

Bariatric Surgery Impacts Levels of Serum Lipids during Pregnancy

INTRODUCTION

Bariatric surgery confers a high risk for nutritional deficiencies that could affect physiologic adaptation of lipids during pregnancy. We aimed to evaluate differences in serum lipids in pregnant women after bariatric surgery compared to obese and lean mothers.

METHODS

25 women with a history of Roux-en-Y gastric bypass (RYGB), 19 obese and 19 normal-weight controls were included at the 24th-28th gestational week for determination of fasting lipids with follow-up in a subgroup after delivery. Data on neonatal biometry were additionally assessed.

RESULTS

Women after RYGB showed lower total-cholesterol (TC), low-density lipoprotein C (LDL-C), non-high-density lipoprotein C (non-HDL-C) and triglycerides (TG) compared to obese mothers. Despite their higher BMI, women after RYGB showed lower TC, LDL-C and non-HDL-C than normal-weight mothers. Ultrasensitive C-reactive protein was lower in RYGB mothers than in obese ones, reaching values of lean controls. Differences remained unchanged in BMI-matched comparison. Birth weight percentiles of RYGB offspring were associated with maternal TC (r = 0.59, p = 0.021), LDL-C (r = 0.71, p = 0.003), non-HDL (r = 0.59, p = 0.021) but not HDL-C or TG. After delivery, lipids decreased in all women; however, TC and LDL-C showed more attenuated decline in mothers after RYGB than control women.

CONCLUSION

Pregnancies after RYGB show alterations of physiologic patterns in lipid profile. Further studies are required to evaluate whether imbalances in maternal lipids constitute a risk for abnormal fetal growth in this special cohort.

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.

Body weight-dependent and independent improvement in lipid metabolism after Roux-en-Y gastric bypass in ApoE*3Leiden.CETP mice

BACKGROUND/OBJECTIVES

The incidence of obesity and metabolic syndrome (MetS) has rapidly increased worldwide. Roux-en-Y gastric bypass (RYGB) achieves long-term weight loss and improves MetS-associated comorbidities. Using a mouse model with a humanized lipoprotein metabolism, we elucidated whether improvements in lipid and glucose metabolism after RYGB surgery are body weight loss-dependent or not.

SUBJECTS/METHODS

Male ApoE*3Leiden.CETP (ApoE3L.CETP) mice fed Western type diet for 6 weeks underwent RYGB or Sham surgery. Sham groups were either fed ad libitum or were body weight-matched (BWm) to the RYGB mice to discriminate surgical effects from body weight loss-associated effects. Before and after surgery, plasma was collected to assess the metabolic profile, and glucose tolerance and insulin sensitivity were tested. Twenty days after surgery, mice were sacrificed, and liver was collected to assess metabolic, histological and global gene expression changes after surgery.

RESULTS

RYGB induced a marked reduction in body weight, which was also achieved by severe food restriction in BWm mice, and total fat mass compared to Sham ad libitum mice (Sham AL). Total cholesterol, non-high-density lipoprotein cholesterol (non-HDL-C) and ceramide were strongly reduced 20 days after surgery in RYGB compared to BWm mice. Glucose tolerance and insulin sensitivity improved 13 days after surgery similarly in RYGB and BWm mice. Liver histology confirmed lipid reduction in RYGB and BWm mice while the transcriptomics data indicated altered genes expression in lipid metabolism.

CONCLUSIONS

RYGB surgery improves glucose metabolism and greatly ameliorates lipid metabolism in part in a body weight-dependent manner. Given that ApoE3L.CETP mice were extensively studied to describe the MetS, and given that RYGB improved ceramide after surgery, our data confirmed the usefulness of ApoE3L.CETP mice after RYGB in deciphering the metabolic improvements to treat the MetS.

Assessment of Cardiometabolic Risk Factors, Physical Activity Levels, and Quality of Life in Stratified Groups up to 10 Years after Bariatric Surgery

Obesity is a highly prevalent chronic metabolic disease, with an increasing incidence, and is currently approaching epidemic proportions in developing countries. Ouraim was to evaluate the activity levels, quality of life (QoL), clinical parameters, laboratory parameters, and cardiometabolic risk factors afterbariatric surgery (BS). We classified78 patients who underwentBS into four groups, as follows: Those evaluated 1–2 years after BS (BS2), 2–4 years after BS (BS4), 4–6 years after BS (BS6), and 6–10 years after BS (BS+6). Body weight (BW), body mass index (BMI), comorbidities associated with obesity (ACRO), physical activity level, and QoL were evaluated. Patients exhibited improvements in BW, BMI, cardiometabolic risk, hypertension, dyslipidemia, and diabetes and significant changes in lipid profiles in the first postoperative yearafter BS.The physical activity level inthe BS2, BS4, and BS6 groups was increased, compared with that in the first postoperative year, with a decrease in International Physical Activity Questionnaire scores at 1 year in the BS2 (207.50 ± 30.79), BS4 (210.67 ± 33.69), and BS6 (220.00 ± 42.78) groups. The QoL of patients in theBS2 and BS4 groups was excellent and that of patients in the BS4 and BS+6 groupswas very good. These findings suggest that BS promoted improved physical activity levels and QoL and reduced comorbidities in patients with morbid obesity.

Roux-en-Y gastric bypass surgery reprograms enterocyte triglyceride metabolism and postprandial secretion in rats

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) surgery produces rapid and persistent reductions in plasma triglyceride (TG) levels associated with fewer cardiovascular events. The mechanisms of the reduction in systemic TG levels remain unclear. We hypothesized that RYGB reduces intestinal TG secretion via altered enterocyte lipid handling.

METHODS

RYGB or Sham surgery was performed in diet-induced obese, insulin-resistant male Sprague-Dawley rats. First, we tested whether RYGB reduced test meal-induced TG levels in the intestinal lymph, a direct readout of enterocyte lipid secretion. Second, we examined whether RYGB modified TG enterocyte secretion at the single lipid level and in comparison to other lipid subclasses, applying mass spectrometry lipidomics to the intestinal lymph of RYGB and Sham rats (0-21 days after surgery). Third, we explored whether RYGB modulated the metabolic characteristics of primary enterocytes using transcriptional and functional assays relevant to TG absorption, reesterification, storage in lipid droplets, and oxidation.

RESULTS

RYGB reduced overall postprandial TG concentrations compared to Sham surgery in plasma and intestinal lymph similarly. RYGB reduced lymphatic TG concentrations more than other lipid subclasses, and shifted the remaining TG pool towards long-chain, unsaturated species. In enterocytes of fasted RYGB rats, lipid uptake was transcriptionally (Fatp4, Fabp2, Cd36) and functionally reduced compared to Sham, whereas TG reesterification genes were upregulated.

CONCLUSION

Our results show that RYGB substantially reduces intestinal TG secretion and modifies enterocyte lipid absorption and handling in rats. These changes likely contribute to the improvements in the plasma TG profile observed after RYGB in humans.

Insulin translates unfavourable lifestyle into obesity

Lifestyle factors conferring increased diabetes risk are associated with elevated basal insulin levels (hyperinsulinaemia). The latter predicts later obesity in children and adolescents.A causal role of hyperinsulinaemia for adipose tissue growth is probable because pharmacological reduction of insulin secretion lowers body weight in people who are obese. Genetic inactivation of insulin gene alleles in mice also lowers their systemic insulin levels and prevents or ameliorates high-fat diet-induced obesity. Hyperinsulinaemia causes weight gain because of a physiological property of insulin. Insulin levels that are on the high side of normal, or which are slightly elevated, are sufficient to suppress lipolysis and promote lipogenesis in adipocytes. The effect of insulin on glucose transport or hepatic glucose production requires six or two times higher hormone levels, respectively.It seems justified to suggest a lifestyle that avoids high insulin levels in order to limit anabolic fat tissue activity.

Analysis of obese patients' medical conditions in the pre and postoperative periods of bariatric surgery

Objective

to compare the clinical conditions of obese patients in the pre and postoperative period of bariatric surgery.

Methods

we carried out a descriptive, retrospective, quantitative study by consulting the charts of 134 patients who underwent bariatric surgery in the period from 2009 to 2014. We collected the data between September and November 2015. We performed a descriptive statistical analysis and comparative analysis of anthropometric, metabolic, biochemical and clinical variables, considering six months before and after surgery.

Results

the majority of the patients were female (91.8%), with a higher prevalence (35%) in the age group 18-29 years old, complete high-school education (65.6%) and grade III obesity (60.4%). Six months after surgery, weight and lipid profile reduction were significant in both genders, but the impact on biochemical, anthropometric, metabolic and clinical parameters was significant only in female subjects, with a reduction in morbidities associated with obesity, such as arterial hypertension, diabetes mellitus, dyslipidemia and metabolic syndrome and in the use of drugs to control them.

Conclusion

bariatric surgery was effective in weight loss, with improvements in anthropometric, metabolic and biochemical parameters and in the reduction of morbidities associated with obesity.

Hypercholesterolaemia - practical information for non-specialists

Hypercholesterolaemia is amongst the most common conditions encountered in the medical profession. It remains one of the key modifiable cardiovascular risk factors and there have been recent advances in the risk stratification methods and treatment options available. In this review, we provide a background into hypercholesterolaemia for non-specialists and consider the merits of the different risk assessment tools available. We also provide detailed considerations as to: i) when to start treatment, ii) what targets to aim for and iii) the role of low density lipoprotein cholesterol.

Changes in Bile Acid Profile After Laparoscopic Sleeve Gastrectomy are Associated with Improvements in Metabolic Profile and Fatty Liver Disease

BACKGROUND

Bile acids (BA) modulate lipid and glucose metabolism in a feedback loop through production of fibroblast growth factor (FGF) 19 in the terminal ileum. Changes in BA after bariatric surgery may lead to improvements in the metabolic syndrome, including fatty liver disease. This study investigated the relationship between BA and metabolic and inflammatory profiles after laparoscopic sleeve gastrectomy (LSG).

METHODS

Patients undergoing LSG had fasting blood samples taken pre-operatively and 6 months post-surgery. Liver injury was measured using cytokeratin (CK) 18 fragments. BA were measured using liquid chromatography tandem-mass spectrometry. FGF-19 was measured using enzyme-linked immunosorbent assay.

RESULTS

The study included 18 patients (12 females), with mean age 46.3 years (SEM ± 2.9) and BMI 60.1 kg/m(2) (±2.6). After 6 months, patients lost 39.8 kg (±3.1; p < 0.001). Fourteen patients (78 %) had steatosis. FGF-19 increased from median 128.1 (IQR 89.4-210.1) to 177.1 (121.8-288.9, p = 0.045) at 6 months. Although total BA did not change, primary glycine- and taurine-conjugated BA, cholic acid decreased, and secondary BA, glycine-conjugated urodeoxycholic acid increased over the study period. These changes are associated with reduction in insulin resistance, pro-inflammatory cytokines and CK-18 levels.

CONCLUSIONS

The profile of individual BA is altered after LSG. These changes occur in the presence of reductions in inflammatory cytokines and markers of liver injury. This study supports evidence from recent animal models that LSG may have an effect on fatty liver through changes in BA metabolism.

Acute and Chronic Impact of Bariatric Surgery on Plasma LDL Cholesterol and PCSK9 Levels in Patients With Severe Obesity

CONTEXT

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of low-density lipoprotein cholesterol (LDL-C) concentrations. In patients with severe obesity, biliopancreatic diversion with duodenal switch (BPD-DS) surgery induces substantial weight loss and influences lipoprotein metabolism. The effect of BPD-DS on PCSK9 levels is unknown.

OBJECTIVES

To determine the acute and chronic impact of BPD-DS on PCSK9 levels and whether the acute impact of BPD-DS could be explained by BPD-DS-associated caloric restriction (CR).

DESIGN, SETTINGS, AND PARTICIPANTS

PCSK9 levels were measured in 20 men and 49 women (age, 41.5 ± 11.1 years) with severe obesity before, 24 hours, 5 days, and 6 and 12 months after BPD-DS and in a comparable control group (n = 31) at baseline and at 6 and 12 months. PCSK9 levels were also measured during 3-day CR in patients (n = 7) with severe obesity and type 2 diabetes.

RESULTS

PCSK9 levels increased 13.4% after 24 hours (248.7 ± 64.8 to 269.7 ± 63.8 ng/mL; P = 0,02) and decreased 9.5% at 12 months compared with baseline (217.6 ± 43.0 ng/mL; P < 0,0001). LDL-C levels decreased 36.2% after 24 hours (2.6 ± 0.7 to 1.7 ± 0.6 mmol/L; P < 0.0001) and 30% at 12 months compared with baseline (1.7 ± 0.5 mmol/L; P < 0.0001). Compared with baseline levels, PCSK9 levels were lower at day 2 but not at day 1 or 3 after CR.

CONCLUSION

BPD-DS is associated with acute increases in PCSK9 levels that do not appear to be explained by CR but may be due to an acute response following surgery. BPD-DS induces chronic reductions in both PCSK9 and LDL-C levels.

Body Weight Reduction and Biochemical Parameters of the Patients After RYGB and SG Bariatric Procedures in 12-Month Observation

Background

The aim of this study was to evaluate the effect of sleeve gastrectomy (SG) and Roux-en-Y-bypass (RYGB) on anthropometric and biochemical parameters, including changes in glucose levels, lipid profile and liver function. Drastic decrease in all lipid fractions a few weeks or months after the surgery could be regarded as favourable, but low level of HDL is an independent risk factor for heart diseases. Extreme load on the liver without preparation of the patient to the surgery can have negative consequences.

Methods

The test group comprised of 40 female patients at the age of 42.96 with average body weight of 131.56 kg and BMI 46.49. Biochemical analyses were performed using calorimetric method.

Results

No statistically significant differences were observed in glucose levels between the two types of procedures. The highest differences were noted for triglycerides levels, which decreased, as well as all cholesterol fractions, after RYGB, but were increasing during the first months after SG procedure. Changes in lipid profile, caused by the reduction of all lipid fractions, were more visible after RYGB. The decrease in total cholesterol directly and activity of liver enzymes after the procedure was as higher after RYGB as after SG. Increased activity of transaminases indicates significant liver overload.

Conclusions

With the selection of groups of patients with similar initial parameters, it is not clear whether the differences between the two procedures when assessing the improvement of glycaemia are significant. However, due to invasive character of RYGB, liver overload lasting several months and lifelong limited absorption of nutrients, the possibility of SG procedure should be considered as a first option.

Alterations in fatty acid metabolism in response to obesity surgery combined with dietary counseling

Background:

The effects of obesity surgery on serum and adipose tissue fatty acid (FA) profile and FA metabolism may modify the risk of obesity-related diseases.

Methods:

We measured serum (n=122) and adipose tissue (n=24) FA composition and adipose tissue mRNA expression of genes regulating FA metabolism (n=100) in participants of the Kuopio Obesity Surgery Study (KOBS, age 47.2±8.7 years, BMI 44.6±6.0, 40 men, 82 women) before and one year after obesity surgery. As part of the surgery protocol, all the subjects were instructed to add sources of unsaturated fatty acids, such as rapeseed oil and fatty fish, into their diet. The results were compared with changes in serum FA composition in 122 subjects from the Finnish Diabetes Prevention study (DPS) (age 54.3±7.1 years, BMI 32.2±4.6, 28 men, 94 women).

Results:

The proportion of saturated FAs decreased and the proportion of n-3 and n-6 FAs increased in serum triglycerides after obesity surgery (all P<0.002). Weight loss predicted changes in quantitative amounts of saturated FAs, monounsaturated FAs, n-3 and n-6 FAs in triglycerides (P<0.002 for all). Moreover, the changes in adipose tissue FAs reflected the changes in serum FAs, and some of the changes were associated with mRNA expression of elongases and desaturases in adipose tissue (all P<0.05). In line with this the estimated activity of elongase (18:1 n-7/16:1 n-7) increased significantly after obesity surgery in all lipid fractions (all P<4 × 10⁻⁷) and the increase in the estimated activity of D5D in triglycerides was associated with higher weight loss (r=0.415, P<2 × 10⁻⁶). Changes in serum FA profile were similar after obesity surgery and lifestyle intervention, except for the change in the absolute amounts of n-3 FAs between the two studies (P=0.044).

Conclusions:

Beneficial changes in serum and adipose tissue FAs after obesity surgery could be associated with changes in endogenous metabolism and diet.

TSH Normalization in Bariatric Surgery Patients After the Switch from L-Thyroxine in Tablet to an Oral Liquid Formulation

OBJECTIVE

Drug malabsorption is one of the potential troubles after bariatric surgery. Evidence for diminished levothyroxine (L-T4) absorption has been reported in patients after bariatric surgery.

METHODS

This study reports 17 cases of hypothyroid patients [who were well replaced with thyroxine tablets (for >1 year) to euthyroid thyrotropin (TSH) levels before surgery (13 Roux-en-Y gastric bypasses (RYGB); 4 biliary pancreatic diversions (BPD))]. From 3 to 8 months after surgery, these patients had elevated TSH levels. Patients were then switched from oral tablets to a liquid L-T4 formulation (with the same dosage, 30 min before breakfast).

RESULTS

Two-three months after the switch, TSH was significantly reduced both in patients treated with RYGB, as in those treated with BPD, while FT4 and FT3 levels were not significantly changed (RYGB group, TSH μIU/mL: 7.58 ± 3.07 vs 3.808 ± 1.83, P < 0.001; BPD group, TSH μIU/mL: 8.82 ± 2.76 vs 3.12 ± 1.33, P < 0.01).

CONCLUSIONS

These results first show that liquid L-T4 could prevent the problem of malabsorption in patients with BPD and confirm those of previous studies in patients submitted to RYGB, suggesting that the L-T4 oral liquid formulation could circumvent malabsorption after bariatric surgery.

Lipid changes 8 years post gastric bypass in adolescents with severe obesity (FABS-5+ study)

OBJECTIVE

Severe obesity in adolescents is increasing and few effective treatments exist. Bariatric surgery is one option, but the extent to which surgery influences cardiovascular risk factors over time in youth is not clear. We hypothesized that Roux-en Y gastric bypass (RYGB) would be associated with sustained improvements in lipids over time (>5 years).

PARTICIPANTS/METHODS

Youth who underwent RYGB from 2001 to 2007 were recruited for the Follow-up of Adolescent Bariatric Surgery-5+ (FABS-5+) in 2011-2014. Baseline body mass index (BMI) and lipids were abstracted from medical records. Follow-up data were obtained at a research visit. Analyses included paired t-tests to assess changes in BMI and lipids over time. General linear models were used to evaluate predictors of high-density lipoprotein (HDL) and non-HDL-cholesterol at follow-up. A non-operative group was recruited for comparison.

RESULTS

Surgical participants (n=58) were a mean±s.d. age of 17±2 years at baseline and 25±2 years at long-term follow-up. Eighty-six percent were Caucasian and 64% were female. At long-term follow-up BMI decreased by 29% and all lipids (except total cholesterol) significantly improved (P<0.01). Female sex was a significant predictor of non-HDL-cholesterol level at 1 year, while change in BMI from 1 year to long-term follow-up was a significant predictor of non-HDL-cholesterol and HDL-cholesterol during the same interval (P<0.05). In the non-operative group, BMI increased by 8% and lipid parameters were unchanged.

CONCLUSIONS

This is the longest and most complete follow-up of youth following RYGB. Weight loss maintenance over time was significantly associated with improvements in lipid profile over 5 years.

Treatment of Obesity: Weight Loss and Bariatric Surgery

This review focuses on the mechanisms underlying, and indications for, bariatric surgery in the reduction of cardiovascular disease (CVD), as well as other expected benefits of this intervention. The fundamental basis for bariatric surgery for the purpose of accomplishing weight loss is the determination that severe obesity is a disease associated with multiple adverse effects on health, which can be reversed or improved by successful weight loss in patients who have been unable to sustain weight loss by nonsurgical means. An explanation of possible indications for weight loss surgery as well as specific bariatric surgical procedures is presented, along with review of the safety literature of such procedures. Procedures that are less invasive or those that involve less gastrointestinal rearrangement accomplish considerably less weight loss but have substantially lower perioperative and longer-term risk. The ultimate benefit of weight reduction relates to the reduction of the comorbidities, quality of life, and all-cause mortality. With weight loss being the underlying justification for bariatric surgery in ameliorating CVD risk, current evidence-based research is discussed concerning body fat distribution, dyslipidemia, hypertension, diabetes mellitus, inflammation, obstructive sleep apnea, and others. The rationale for bariatric surgery reducing CVD events is discussed and juxtaposed with impacts on all-cause mortalities. Given the improvement of established obesity-related CVD risk factors after weight loss, it is reasonable to expect a reduction of CVD events and related mortality after weight loss in populations with obesity. The quality of the current evidence is reviewed, and future research opportunities and summaries are stated.

Early Metabolic Improvement After Bariatric Surgery: The First Steps Toward Remission of Type 2 Diabetes

The introduction of bariatric surgery into clinical practice in the 1980s was followed by a relatively long watch-and-wait period before the very rapid accumulation of scientific literature, over the past decade, concerning its clinical effectiveness and safety and its mechanisms of action in the treatment of obesity. These surgical procedures now emerge as the most effective therapeutic modality to induce long-term remission of type 2 diabetes. Recent research has shed light on the potential mechanisms leading to the profound improvement of glucose homeostasis following most bariatric surgery procedures. These mechanisms can be classified as weight loss dependent and independent, both playing sequential and then synergistic antidiabetes roles. Many groups, including our own, have contributed to our understanding of the relative roles of these mechanisms at differing time periods following these procedures. Here we summarize what we currently know about the mechanisms underlying the very rapid, weight loss-independent improvement in glucose homeostasis after bariatric surgery. Beyond its impact in the field of bariatric surgery, this new knowledge about the very rapid in vivo "reverse engineering" of type 2 diabetes actually provides unique insights into the intricate and complex mechanisms linking nutrition and obesity with the development of this disease.

Metabolic improvements following Roux-en-Y surgery assessed by solid meal test in subjects with short duration type 2 diabetes

BACKGROUND

Glucose homeostasis improves within days following Roux-en-Y gastric bypass (RYGB) surgery. The dynamic metabolic response to caloric intake following RYGB has been assessed using liquid mixed meal tolerance tests (MMTT). Few studies have evaluated the glycemic and hormonal response to a solid mixed meal in subjects with diabetes prior to, and within the first month following RYGB.

METHODS

Seventeen women with type 2 diabetes of less than 5 years duration participated. Fasting measures of glucose homeostasis, lipids and gut hormones were obtained pre- and post-surgery. MMTT utilizing a solid 4 oz chocolate pudding performed pre-, 2 and 4 weeks post-surgery. Metabolic response to 4 and 2 oz MMTT assessed in five diabetic subjects not undergoing surgery.

RESULTS

Significant reductions in fasting glucose and insulin at 3 days, and in fasting betatrophin, triglycerides and total cholesterol at 2 weeks post-surgery. Hepatic insulin clearance was greater at 3 days post-surgery. Subjects exhibited less hunger and greater feelings of fullness and satisfaction during the MMTT while consuming 52.9 ± 6.5% and 51.0 ± 6.5% of the meal at 2 and 4 weeks post-surgery respectively. At 2 weeks post-surgery, glucose and insulin response to MMTT were improved, with greater GLP-1 and PYY secretion. Improved response to solid MMTT not replicated by consumption of smaller pudding volume in diabetic non-surgical subjects.

CONCLUSIONS

With a test meal of size and composition representative of the routine diet of post-RYGB subjects, improved glycemic and gut hormone responses occur which cannot be replicated by reducing the size of the MMTT in diabetic subjects not undergoing surgery.

TRIAL REGISTRATION

Clinical Trials.gov Identifier: NCT00957957 August 11, 2009.

Maladaptive Eating Behaviors and Metabolic Profile in Patients Submitted to Bariatric Surgery: a Longitudinal Study

PURPOSE

This study aims to investigate relations between maladaptive eating behaviors (MEB) and metabolic profile in patients submitted to bariatric surgery.

METHODS

Longitudinal study including 70 patients before (T0), in the first year after surgery assessment (T1), and the second year after surgery assessment (T2). A face-to-face clinical interview assessed MEB at T0 and T2. Blood samples were collected at T0, T1, and T2 to assess fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), insulin, insulin resistance (IR), and triglycerides (TG). Mixed model analyses with growth curves tested the differences between patients with MEB (M group) and non-MEB patients (NM group) on the course of metabolic parameters, while controlling for total weight loss and type of surgery.

RESULTS

No differences between both groups were reached for levels of FPG (F(1, 140) = 2.936, p = 0.089), HbA1c (F(1, 96) = 0.099, p = 0.754), insulin (F(1, 121) = 0.146, p = 0.703), IR (F(1, 60) = 0.976, p = 0.327), and TG (F(1, 128) = 0.725, p = 0.396). All parameters improved from T0 to T1 for both groups. A distinct trend on the course of metabolic markers in the M group but not the NM group is observed, presenting an increase in HbA1c levels, insulin, and TG levels.

CONCLUSIONS

Both groups progressed favorably in the first 12 months of surgery. MEB may be associated with a trend for deterioration of metabolic profile after 12 months of surgery. The study should be replicated with longer-term assessments and a larger sample size.

Practical Recommendations of the Obesity Management Task Force of the European Association for the Study of Obesity for the Post-Bariatric Surgery Medical Management

Bariatric surgery is today the most effective long-term therapy for the management of patients with severe obesity, and its use is recommended by the relevant guidelines of the management of obesity in adults. Bariatric surgery is in general safe and effective, but it can cause new clinical problems and is associated with specific diagnostic, preventive and therapeutic needs. For clinicians, the acquisition of special knowledge and skills is required in order to deliver appropriate and effective care to the post-bariatric patient. In the present recommendations, the basic notions needed to provide first-level adequate medical care to post-bariatric patients are summarised. Basic information about nutrition, management of co-morbidities, pregnancy, psychological issues as well as weight regain prevention and management is derived from current evidences and existing guidelines. A short list of clinical practical recommendations is included for each item. It remains clear that referral to a bariatric multidisciplinary centre, preferably the one performing the original procedure, should be considered in case of more complex clinical situations.

Improved glucose metabolism following bariatric surgery is associated with increased circulating bile acid concentrations and remodeling of the gut microbiome

Clinical studies have indicated that circulating bile acid (BA) concentrations increase following bariatric surgery, especially following malabsorptive procedures such as Roux-en-Y gastric bypasses (RYGB). Moreover, total circulating BA concentrations in patients following RYGB are positively correlated with serum glucagon-like peptide-1 concentrations and inversely correlated with postprandial glucose concentrations. Overall, these data suggest that the increased circulating BA concentrations following bariatric surgery - independently of calorie restriction and body-weight loss - could contribute, at least in part, to improvements in insulin sensitivity, incretin hormone secretion, and postprandial glycemia, leading to the remission of type-2 diabetes (T2DM). In humans, the primary and secondary BA pool size is dependent on the rate of biosynthesis and the enterohepatic circulation of BAs, as well as on the gut microbiota, which play a crucial role in BA biotransformation. Moreover, BAs and gut microbiota are closely integrated and affect each other. Thus, the alterations in bile flow that result from anatomical changes caused by bariatric surgery and changes in gut microbiome may influence circulating BA concentrations and could subsequently contribute to T2DM remission following RYGB. Research data coming largely from animal and cell culture models suggest that BAs can contribute, via nuclear farnezoid X receptor (FXR) and membrane G-protein-receptor (TGR-5), to beneficial effects on glucose metabolism. It is therefore likely that FXR, TGR-5, and BAs play a similar role in glucose metabolism following bariatric surgery in humans. The objective of this review is to discuss in detail the results of published studies that show how bariatric surgery affects glucose metabolism and subsequently T2DM remission.