Effects of Two Preoperatory Weight Loss Diets on Hepatic Volume, Metabolic Parameters, and Surgical Complications in Morbid Obese Bariatric Surgery Candidates: a Randomized Clinical Trial

Low-calorie diets are effective for weight loss in patients undergoing benign upper gastrointestinal surgery: a systematic review and meta-analysis

BACKGROUND

Obesity may increase surgical complexity in patients undergoing abdominal surgery by limiting visualization and increasing the risk of peri-operative complications. A preoperative reduction in weight and liver volume may improve surgical outcomes. The aim of our study was to evaluate the efficacy of a low-calorie diet (LCD) versus a very low-calorie diet (VLCD) in reducing weight and liver volume prior to laparoscopic surgery.

METHODS

A systematic search was conducted using the following inclusion criteria: obese patients undergoing preoperative weight loss using a VLCD or LCD, evaluation of liver volume reduction, and the use of an imaging modality before and after the diet.

RESULTS

A total of 814 patients from 21 different studies were included in this systematic review and meta-analysis, with 544 female patients (66.8%) and a mean age range between 24 and 54 years old. There was a total mean weight loss of 6.42% and mean liver volume reduction of 16.7%. Meta-analysis demonstrated that a preoperative diet (LCD or VLCD) significantly reduced weight [SMD = - 0.68; 95% CI (- 0.93, - 0.42), I2 = 82%, p ≤ 0.01] and liver volume [SMD = - 2.03; 95% CI (- 4.00, - 0.06), I2 = 94%, p ≤ 0.01]. When assessed individually, a VLCD led to significant weight reduction [SMD = - 0.79; CI (- 1.24; - 0.34), p ≤ 0.01, I2 = 90%], as did an LCD [SMD = - 0.60; CI (- 0.90; - 0.29), p ≤ 0.01, I2 = 68%). Similarly, there was a significant reduction in liver volume following a VLCD [SMD = - 1.40; CI (- 2.77, - 0.03), p ≤ 0.01, I2 = 96%], and an LCD [SMD = - 2.66; CI (- 6.13, 0.81), p ≤ 0.01, I2 = 93%]. However, there was no significant difference between the two regimens.

CONCLUSIONS

Preoperative restrictive calorie diets are effective in reducing weight and liver volume prior to laparoscopic surgery. Whilst a VLCD was better than an LCD at reducing both weight and liver volume, the difference was not significant.

Evaluate the Effects of Different Types of Preoperative Restricted Calorie Diets on Weight, Body Mass Index, Operation Time and Hospital Stay in Patients Undergoing Bariatric Surgery: a Systematic Review and Meta Analysis Study

Previous studies investigated low-calorie diets (LCD), very-low-calorie diets (VLCD), and very-low-calorie ketogenic diets (VLCKD) in relation to weight loss and outcomes for bariatric surgery patients. However, the overall effects of these diets on various outcomes remain unclear. This study aimed to assess the impact of preoperative restricted calorie diets on weight, body mass index (BMI), operation time (OT), and hospital stay (HS) in bariatric surgery patients. Seventeen articles were analyzed, revealing the highest weight loss (-8.62) and BMI reduction (-5.75) with VLCKD. Due to insufficient data, the impact of these diets on OT and HS could not be determined. Further interventional studies are required to determine the ideal preoperative diet that achieves optimal weight loss, patient compliance, tolerance, acceptance, and surgical outcomes.

Enhanced Recovery After Surgery: Exploring the Advances and Strategies

Enhanced recovery after surgery (ERAS) has emerged as a paradigm-shifting approach in perioperative care, aimed at optimizing patient outcomes, accelerating recovery, and minimizing hospital stays. This review delves into the latest advances and strategies within the field of ERAS, encompassing a comprehensive examination of preoperative, intraoperative, and postoperative interventions. By analyzing an array of clinical studies, meta-analyses, and implementation experiences, this review highlights the multifaceted elements contributing to the success of ERAS programs. Key components such as preoperative patient education, minimally invasive surgical techniques, tailored anesthesia protocols, judicious fluid management, optimized pain control, early ambulation, and structured nutritional support are thoroughly explored. Furthermore, the review delves into the intricacies of ERAS implementation across diverse surgical specialties, emphasizing the significance of multidisciplinary collaboration, protocol customization, and sustained quality improvement initiatives. The analysis not only showcases the tangible benefits of ERAS, including reduced complication rates, shortened hospital stays, and enhanced patient satisfaction, but also underscores the challenges and barriers that medical professionals encounter during program adoption. By synthesizing the current state of ERAS research and practice, this review provides clinicians, administrators, and researchers with valuable insights into the evolving landscape of perioperative care, fostering a deeper understanding of ERAS as a holistic approach that transcends traditional surgical pathways.

Nutrition, Physical Activity, and Prescription of Supplements in Pre- and Post-bariatric Surgery Patients: An Updated Comprehensive Practical Guideline

Only in the USA, 315 billion dollars are spent annually on the medical cost of obesity in adult patients. Till now, bariatric surgery is the most effective method for treating obesity and can play an essential role in reducing the direct and indirect costs of obesity treatment. Nonetheless, there are few comprehensive guidelines which include nutrition, physical activity, and supplements, before and after surgery. The purpose of the present narrative review is to provide an updated and comprehensive practical guideline to help multidisciplinary teams. The core keywords include nutrition, diet, physical activity, exercise, supplements, macronutrients, micronutrients, weight reduction, bariatric surgery, Roux-en-Y Gastric Bypass, Sleeve Gastrostomy, Laparoscopic Adjustable Gastric Banding, and Biliopancreatic diversion with duodenal switch which were searched in databases including PubMed/Medline, Cochrane, and some other sources such as Google Scholar. We answered questions in five important areas: (a) nutritional strategies before bariatric surgery, (b) nutrition after bariatric surgery, (c) physical activity before and after bariatric surgery, (d) weight regain after bariatric surgery, and (e) micronutrient assessments and recommendations before and after bariatric surgery. Some new items were added in this updated guideline including "weight regain" and "pregnancy after bariatric surgery." Other fields were updated based on new evidence and guidelines.

Very low energy diets prior to bariatric surgery may reduce postoperative morbidity: a systematic review and meta-analysis of randomized controlled trials

Purpose

To optimize patients prior to bariatric surgery, very low energy diets (VLEDs) are often employed for 2-4 weeks preoperatively. They are known to result in preoperative weight loss, decrease liver volume, and decrease surgeon-perceived operative difficulty. Their impact on postoperative morbidity has been less extensively studied. We performed a focused systematic review and meta-analysis with the aim of comparing preoperative VLEDs prior to bariatric surgery with controls in terms of overall postoperative morbidity.

Methods

MEDLINE, Embase, and CENTRAL were searched from database inception to February 2023. Articles were eligible for inclusion if they were randomized controlled trials (RCTs) comparing postoperative morbidity in adult patients (i.e., over the age of 18) receiving a VLED with liquid formulation to those receiving a non-VLED control prior to elective bariatric surgery. Outcomes included overall 30-day postoperative morbidity and preoperative weight loss. An inverse variance meta-analysis was performed with GRADE assessment of the quality of evidence.

Results

After reviewing 2,525 citations, four RCTs with 294 patients receiving preoperative VLEDs with liquid formulation and 294 patients receiving a non-VLED control met inclusion. Patients receiving VLED experienced significantly more preoperative weight loss than patients receiving control (mean difference (MD) 3.38 kg, 95% confidence interval (CI) 1.06-5.70, p = 0.004, I² = 95%). According to low certainty evidence, there was a non-significant reduction in 30-day postoperative morbidity in patients receiving VLED prior to bariatric surgery (risk ratio (RR) 0.67, 95%CI 0.39-1.17, p = 0.16, I² = 0%).

Conclusion

The impact of preoperative VLEDs on postoperative outcomes following bariatric surgery remains unclear. It is possible that VLEDs may contribute to decreased postoperative morbidity, but further larger prospective trials are required to investigate the signal identified in this study.

Variation and outcomes of liver-reducing dietary regimens before bariatric surgery: a national retrospective cohort study

BACKGROUND

Liver-reducing diets (LRDs) are mandated prior to bariatric surgery, but there are no guidelines on their implementation.

OBJECTIVE

To establish the variation and effectiveness of LRDs utilized in clinical practice.

SETTING

A nationwide, multicenter, retrospective cohort study.

METHODS

A total of 1699 adult patients across 14 bariatric centers in the United Kingdom were included. Multilevel logistic regression models were developed to examine factors predictive of 5% weight loss.

RESULTS

Most centers (n = 9) prescribed an 800- to 1000-kcal diet, but the duration and formulation of diet was variable. Overall, 30.6% (n = 510) of patients achieved 5% weight loss during the LRD. After adjustment for preoperative weight, women had reduced odds (odds ratio [OR], .65; 95% confidence interval [CI], .48-.88; P = .005), while increasing age (OR, 1.01; 95% CI, 1.00-1.02; P = .043) and having type 2 diabetes (OR, 1.49; 95% CI, 1.16-1.92; P = .002) increased odds of 5% weight loss. A normal consistency food LRD (OR, .64; 95% CI, .42-.98; P = .041) and energy prescription of >1200 kcals/d (OR, .33; 95% CI, .13-.83; P = .019) reduced odds, while an LRD with a duration of 3 weeks (OR, 2.28; 95% CI, 1.02-5.09; P = .044) or greater increased odds of 5% weight loss.

CONCLUSIONS

There is wide variation in how LRDs are delivered in clinical practice, highlighting the need for an evidence-based consensus. Our findings suggest the optimal LRD before bariatric surgery contains 800 to 1200 kcals/d over a duration of 3 to 4 weeks. Further research is required to determine the optimal formulation of LRD and whether women may require a lower-energy LRD than men.

Prehabilitation of overweight and obese patients with dysglycemia awaiting bariatric surgery: Predicting the success of obesity treatment

Bariatric surgery offers the best health results in overweight and obese patients but is not a risk and/or complication-free treatment. In cases with additional hyperglycemia, the burden of surgery can be even higher and alter both short-term and long-term outcomes. Although bariatric surgery offers glycemic improvements and in the case of early onset diabetes disease remission, weight loss results are lower than for obese patients without diabetes. Different multimodal programs, usually including interventions related to patients' performance, nutritional and psychological status as well as currently available pharmacotherapy before the surgery itself might considerably improve the immediate and late postoperative course. However, there are still no clear guidelines addressing the prehabilitation of obese patients with dysglycemia undergoing bariatric surgery and therefore no unique protocols to improve patients' health. In this minireview, we summarize the current knowledge on prehabilitation before bariatric surgery procedures in patients with obesity and dysglycemia.

Very low energy diets before nonbariatric surgery: A systematic review and meta-analysis

BACKGROUND

Very low energy diets serve as an intensive approach to weight loss in a short period of time. Although the preoperative use of very low energy diets to optimize patients with obesity before bariatric surgery is well established, the evidence for very low energy diets before other types of surgery remains unclear. The aim of this review was to determine the impact of preoperative very low energy diets on perioperative outcomes in nonbariatric surgery.

METHODS

Medline, EMBASE, CENTRAL, and PubMed were systematically searched from inception through to July 2021. Articles were included if they evaluated very low energy diets use before any type of nonbariatric surgery. The primary outcome was postoperative morbidity. Secondary outcomes included compliance, safety, and preoperative weight loss. A pairwise meta-analyses using inverse variance random effects was performed.

RESULTS

From 792 citations, 13 studies with 395 patients (mean age: 56.5 years, 55.8% female) receiving very low energy diets preoperatively in preparation for nonbariatric surgery were included. Mean duration of preoperative very low energy diets was 6.6 weeks (range, 0.42-17 weeks). Target daily caloric intake ranged from 450 kcal to 1,400 kcal. Compliance with very low energy diets ranged from 94% to 100%. The mean preoperative weight loss ranged from 3.2 kg to 19.2 kg. There were no significant differences in postoperative morbidity (odds ratio, 1.10; 95% confidence interval, 0.64-1.91; P = .72), operative time (standard mean difference -0.35; 95% confidence interval, 1.13-0.43, P = .38), or postoperative length of stay (standard mean difference 0.40, 95% confidence interval -0.11-0.91, P = .12) with very low energy diets.

CONCLUSION

Although the currently available evidence is heterogenous, preoperative very low energy diets are safe, well tolerated, and effectively induce preoperative weight loss in patients undergoing nonbariatric surgery for both benign and malignant disease. Further prospective studies are warranted.

Comparison of a pre-bariatric surgery very low-calorie ketogenic diet and the Mediterranean diet effects on weight loss, metabolic parameters, and liver size reduction

This study compared the effects on weight as well as on metabolic parameters and liver size of a very low-calorie ketogenic diet versus a Mediterranean diet in patients with morbid obesity preparing to undergo bariatric surgery. This prospective comparison study evaluated patients 18-65 years of age who enrolled for bariatric surgery. Study duration was limited to an immediate preoperative period of 15 days. The very low-calorie ketogenic diet incorporated 10-12 kcal/kg/day of energy and 1-1.2 g/kg of protein using Kalibra (Societa Dietetica Medica) (VLCKD-SDM). The Mediterranean diet (MD) included 15-20% protein, 45-50% carbohydrate, and 25-35% fat. Changes in body mass index (BMI), liver size, and anthropometric and metabolic measurements were assessed. Between January 2016 and March 2017, of 45 patients enrolled, 30 completed the study (VLCKD-SDM, n = 15; MD, n = 15). Respective median BMI loss after VLCKD-SDM was 2.7 kg/m² versus MD 1.4 kg/m² (p < 0.05); median fat percentage reduction was 3.2 units versus 1.7 units (p < 0.05). Median liver size decreased 5.5% in the VLCKD-SDM group versus 1.7% in the MD group (p < 0.05). Median total cholesterol, and LDL levels decreased in both groups (p < 0.05), with greater relative decreases in the VLCKD-SDM group. Short-term preoperative diet-based weight loss in patients with morbid obesity preparing for bariatric surgery was significantly greater following a very low-calorie ketogenic diet versus a Mediterranean diet. The very low-calorie diet also significantly improved anthropometric and metabolic parameters and reduced preoperative liver size above that of the MD.

The use of very low-calorie diets in subjects with obesity complicated with nonalcoholic fatty liver disease: A scoping review

This scoping review synthesizes the existing research on the use of very low-calorie diets (VLCDs) in subjects with nonalcoholic fatty liver disease (NAFLD) and end-stage liver disease (ESLD). 19 studies were included, of which 5 were clinical trials, 11 were cohort studies, 1 was a case-control study, and 2 were case series totaling 968 subjects. About 17 studies were focused on patients with NAFLD while the two case series described in patients with ESLD on the transplant list or post-liver transplant. Six studies included subjects managed with VLCDs prior bariatric surgery. Most studies were short term and demonstrated acute improvement of diverse liver biomarkers including liver function tests, indices of hepatosteatosis and reduction in liver size. Adherence rates in these studies were between 69% and 93%. Eight studies did not report any adverse events and four subjects were reported to have discontinued VLCD due to adverse effects in two different studies. Aggregated adverse events were mild. Treatments based on VLCD in subjects with NAFLD seem to be safe and tolerable but can result in mild adverse effects. The findings of this scoping review suggest that the use of VLCD in patients with obesity complicated with NAFLD and potentially in ESLD appear to be effective to induce weight loss and to acutely reduce hepatosteatosis.

Effectiveness and Tolerability of a Two-Week Hypocaloric Protein-Rich Diet Prior to Obesity Surgery with Two Different Diet Interventions: a Prospective Randomized Trial

Purpose

Preoperative very low-calorie diets (VLCDs) have been shown to reduce liver volume and improve bariatric surgery safety. Here, we compare two VLCD that differ in macronutrient composition.

Material/Methods

Ninety patients awaiting obesity surgery were included in a prospective, open-label, randomized mono-centre trial comparing the effects of 2-week preoperative VLCDs: BCM Diät™ (diet 1) versus Optifast™ (diet 2).

Results

Data from 33 patients in diet 1 and 36 in diet 2 could be analysed. There was no significant difference between the two diet intervention arms on outcome parameters. Overall, both VLCD strategies led to a mean weight reduction of 5.24 [4.72–5.76] kg (p < 0.001), mean excess weight loss was 8.2 [7.4–9.1] % (p < 0.001). BMI reduction was 1.81 [1.63–1.99] kg/m² (p < 0.001). Over all patients, the liver volume was reduced by 397 [329–466] ml (p < 0.001), which corresponds to 14.6 [12.4; 16.8] %. Liver fat content was significantly reduced by 18.35 [8.98–27.71] %. Reduction of body weight correlates with liver volume loss.

In addition, hip/waist circumferences, body fat and fat-free mass decreased significantly. We found an increase of ALAT/ASAT and a significant decrease of triglycerides, LDL-cholesterol and HbA1c. Parameters of inflammatory were significantly reduced upon VLCD.

Conclusion

Independently of the macronutrient composition, VLCD leads to a significant decrease of body weight, reduction of liver volume and improved parameters of inflammation, glucose and lipid metabolism. Preoperative diets are widely used in conditioning; however, VLCD should be considered as option for patients with obesity undergoing other abdominal surgeries.

Graphical abstract

Higher Preoperative Weight loss Is Associated with Greater Weight Loss up to 12 Months After Bariatric Surgery

BACKGROUND

Prior research suggested presurgical weight loss is associated with greater total weight loss, resulting in a more effective bariatric intervention. We aimed to assess whether preoperative weight loss is a predictor for total weight loss, and which patient factors are associated with successful weight loss.

METHODS

All patients (N = 773) that underwent primary bariatric surgery between June 2017 and August 2019 were included in this single-center retrospective study. Outcome measures were preoperative weight loss (%preopWL) and total weight loss (%TWL) up to 1 year postoperatively. Patients were divided into 4 groups based on quartiles of %preopWL.

RESULTS

Total weight loss after 1, 6, and 12 months for the upper quartile was 16.9%, 33.4%, and 37.8%, and for the lower quartile 11.8%, 28.9%, and 35.2%, respectively (p < 0.001). Seven hundred fourteen patients (92.4%) were available for the 1-year follow-up. Preoperative weight loss was not associated with the incidence of complications. Independent factors predicting increased %preopWL were mandated preoperative weight loss program (MWP) (p < 0.001), older age (p = 0.005), weight measurement in the week before surgery (p = 0.031), and non-diabetic status (p = 0.010). Predictors for superior %TWL were MWP (p = 0.014), younger age (p = 0.001), non-diabetic status (p = 0.005), female gender (p = 0.001), higher Body Mass Index (p = 0.006), and banded gastric bypass (p = 0.001).

CONCLUSION

Higher preoperative weight loss is associated with persisting greater weight loss up to at least 12 months post-surgery. In order to optimize preoperative weight loss, we recommend extra preoperative support to younger and diabetic patients. We advise nutritional counseling and additional weight measurement in the week before surgery.

A broad focus on additional programmes prior to bariatric surgery: A systematic review

Additional preoperative programmes may be beneficial for candidates who seek bariatric surgery, but there is no consensus on the optimal preparation. This systematic review aimed to summarize the effects of a preoperative programme on weight loss. A literature search was performed for Embase, Cinahl, PubMed and Cochrane Library. Studies on preoperative exercise, behaviour and/or diet programmes administered in adult patients in a bariatric trajectory measuring weight loss were included. Initial results yielded 2148 titles, 70 of which were thoroughly analysed and 37 articles were included, comprising 10 333 patients. Eleven out of 37 studies included postoperative weight loss as an outcome in interventions focused on diet (n = 5), behaviour (n = 2), exercise (n = 2) and a combination of interventions (n = 2). Only one study (9%) which administered exercise as a preoperative programme showed a significant effect on postoperative weight loss. In total, 33 studies included preoperative weight loss as an outcome, which was significant in 64% of the cases. It is difficult to draw conclusions from the investigated data as it was extremely heterogeneous concerning the intensity, duration and administration of a programme. Nevertheless, it seems that a preoperative weight loss programme seems beneficial in terms of preoperative weight loss, postoperative physical activity and improved mental health postinterventional. The use of a core outcome set is recommended for future studies.

The relationship between preoperative weight loss and intra and post-bariatric surgery complications: an appraisal of the current preoperative nutritional strategies

Preoperative weight loss before a bariatric surgery reduces long-term complications, but there is no solid evidence for short-term or perioperative complications. This review highlights recent evidence on dietary protocols and the possible correlation between weight loss and surgical complications. Updated evidence was searched in PubMedDirect with the terms "preoperative very low-calorie diet or very-low-calorie ketogenic diet or low-fat diet or intermittent fasting or Mediterranean diet and bariatric surgery or bariatric surgery complications." The main characteristics of each diet, achievements related to weight loss, liver reduction, peri and postoperative outcomes, surgical complications, tolerance, and adherence to the diet are presented from the selected studies. There are few reports about the Mediterranean diet as a strategy to reach these goals. The VLCKD has been associated with better body weight reduction and lesser postoperative complications risk. However, the results in animal models are still controversial. When comparing VLCD with an LCD, there is no apparent superiority between one against the other one. However, LCD has shown better tolerance and adherence than VLCD. There is still a need for more controlled studies to define the best preoperative dietary treatment for weight loss before bariatric surgery since there are controversial positions regarding this issue.

Additional preconditioning program for bariatric surgery: Any benefits? A large cohort study

Postbariatric outcomes may improve by providing an additional preconditioning program (APP) in targeted patients. However, APPs are a demand for health resources while only little and inconsistent evidence consists to support their effectiveness. This cohort study aims to evaluate the effectiveness of APP, by comparing outcomes of patients with and without such APP. We carried out a retrospective single-centre cohort study in a before-after design. Patients signing up for primary gastric bypass or sleeve gastrectomy and eligible for surgery were included if screened as vulnerable patients. Vulnerable patients screened between September 2017 and March 2018 followed an APP and formed the APP-group. Due to a policy change, APPs were no longer performed since September 2018. Vulnerable patients screened between September 2018 and March 2019 thus did not receive an APP (comparator-group). Multidisciplinary follow-up remained unchanged. Endpoints included percentage total weight loss (%TWL), bodyweight, evolution of comorbidities, protein intake, and number of no-shows. The APP-group comprised 231 patients and the comparator-group 153. %TWL differed statistically significantly at 7 (Δ1.5%, p = .01) and 12 months postoperative (Δ2.8%, p < .01) in favour of the comparator-group, as did bodyweight 12 months postoperative (Δ1.8 kg, p < .01). Statistically significant differences were also found in the evolution of comorbidities, protein intake, and the number of no-shows, most in favour for the comparator-group. APP proofed not to be superior to Non-App. It is debatable whether statically significant differences are clinically relevant given their small magnitude. A care pathway without an APP seems at least as effective as a care pathway without.

The Concept of Indeterminable NASH Inducted by Preoperative Diet and Metabolic Surgery: Analyses of Histopathological and Clinical Features

Practitioners routinely perform intraoperative liver biopsies during laparoscopic sleeve gastrectomy (LSG) to evaluate nonalcoholic fatty liver disease (NAFLD). In some patients, hepatocyte ballooning, inflammation, and fibrosis without steatosis are observed, even in the absence of other etiologies. We call this finding indeterminable nonalcoholic steatohepatitis (Ind-NASH). In this study, we clarified the prevalence, as well as histopathological and clinical features, of Ind-NASH through intraoperative liver biopsy in Japanese patients presenting with severe obesity. We enrolled 63 patients who had undergone LSG and intraoperative liver biopsy. In patients diagnosed with histopathological NASH, we performed protocol liver biopsies at 6 and 12 months after LSG. We statistically analyzed these histopathological findings and clinical parameters and found the prevalence rate of Ind-NASH discovered through intraoperative biopsy to be 15.9%. Protocol liver biopsy also revealed that Ind-NASH was an intermediate condition between NASH and normal liver. The clinical features of patients with Ind-NASH are a higher body weight compared to NASH (134.9 kg vs. 114.7 kg; p = 0.0245), stronger insulin resistance compared to nonalcoholic fatty liver (homeostasis model assessment–insulin resistance: 7.1 vs. 4.9; p = 0.0188), and mild liver dysfunction compared to NASH. Patients with Ind-NASH observed positive weight-loss effects from a preoperative diet compared to the postoperative course (percentage total weight loss: 32.0% vs. 26.7%; p < 0.0001). Patients with Ind-NASH may also be good candidates for metabolic surgery owing to their good treatment response; therefore, efforts should be made by specialists in the near future to deeply discuss and define Ind-NASH.

Guidelines for Perioperative Care in Bariatric Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations: A 2021 Update

Background

This is the second updated Enhanced Recovery After Surgery (ERAS®) Society guideline, presenting a consensus for optimal perioperative care in bariatric surgery and providing recommendations for each ERAS item within the ERAS® protocol.

Methods

A principal literature search was performed utilizing the Pubmed, EMBASE, Cochrane databases and ClinicalTrials.gov through December 2020, with particular attention paid to meta-analyses, randomized controlled trials and large prospective cohort studies. Selected studies were examined, reviewed and graded according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. After critical appraisal of these studies, the group of authors reached consensus regarding recommendations.

Results

The quality of evidence for many ERAS interventions remains relatively low in a bariatric setting and evidence-based practices may need to be extrapolated from other surgeries.

Conclusion

A comprehensive, updated evidence-based consensus was reached and is presented in this review by the ERAS® Society.

Nutritional Management in Bariatric Surgery Patients

The obesity epidemic, mainly due to lifestyle changes in recent decades, leads to serious comorbidities that reduce life expectancy. This situation is affecting the health policies of many nations around the world. Traditional measures such as diet, physical activity, and drugs are often not enough to achieve weight loss goals and to maintain the results over time. Bariatric surgery (BS) includes various techniques, which favor rapid and sustained weight loss. BS is a useful and, in most cases, the best treatment in severe and complicated obesity. In addition, it has a greater benefit/risk ratio than non-surgical traditional therapies. BS can allow the obese patient to lose weight quickly compared with traditional lifestyle changes, and with a greater probability of maintaining the results. Moreover, BS promotes improvements in metabolic parameters, even diabetes remission, and in the quality of life. These changes can lead to an increase of life expectancy by over 6 years on average. The nutrition of people before and after BS must be the subject of indications from a trained staff, and patients must be followed in the subsequent years to reduce the risk of malnutrition and the associated problems. In particular, it is still debated whether it is necessary to lose weight prior to surgery, a procedure that can facilitate the surgeon's work reducing the surgical risk, but at the same time, lengthens preparation times increasing the risks associated with concomitant pathologies. Furthermore, preventing nutritional deficiencies prior to the intervention can improve the results and reduce short- and long-term mortality.

Are body surface area based estimates of liver volume applicable to children with overweight or obesity? An in vivo validation study

The liver is the primary organ responsible for clearing most drugs from the body and thus determines systemic drug concentrations over time. Drug clearance by the liver appears to be directly related to organ size. In children, organ size changes as children age and grow. Liver volume has been correlated with body surface area (BSA) in healthy children and adults and has been estimated by functions of BSA. However, these relationships were derived from "typical" populations and it is unknown whether they extend to estimations of liver volumes for population "outliers," such as children with overweight or obesity, who today represent one-third of the pediatric population. Using computerized tomography or magnetic resonance imaging, this study measured liver volumes in 99 children (2-21 years) with normal weight, overweight, or obesity and compared organ measurements with estimates calculated using an established liver volume equation. A previously developed equation relating BSA to liver volume adequately estimates liver volumes in children, regardless of weight status.

Statement on additional scientific evidence in relation to the essential composition of total diet replacement for weight control

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to revise the Opinion on the essential composition of total diet replacements for weight control (TDRs) regarding the minimum content of linoleic acid (LA) and alpha-linolenic acid (ALA) and the maximum content of magnesium (Mg). Through a comprehensive literature search, human studies were retrieved reporting on LA and ALA concentrations in adipose tissue (AT), on weight loss and gallstone formation following TDR consumption and on diarrhoea after supplemental Mg intake. The distribution of the amount of LA and ALA release from AT during weight loss when consuming TDRs was estimated using statistical simulations. Using the fifth percentile, the coverage of the adequate intake (AI) for both FA was estimated. For the risk of developing diarrhoea when consuming TDRs with an Mg content of 350 mg/day, four cross-over studies using 360-368 mg Mg/day were reviewed. The Panel concludes that (1) there is no need to add LA to TDRs, as the amount released from AT during weight loss when consuming TDRs is sufficient to cover the AI for LA; (2) a minimum of 0.8 g/day ALA is needed in TDRs in order to meet the AI for ALA; (3) the minimum fat content of TDRs of 20 g/day as derived in the Panel's previous opinion is proposed to be maintained until the availability of further evidence, given the considerable uncertainty as to the amount of fat required for reducing the risk of gallstone formation; and (4) the likelihood that Mg-induced diarrhoea occurs at a severity that may be considered of concern for overweight and obese individuals consuming TDRs is low when the total maximum Mg content in TDRs is 350 mg/day.

Validity and efficacy of diets used for preoperative weight reduction among patients qualified for bariatric surgery

INTRODUCTION

Bariatric surgery is the most effective method of weight reduction among patients suffering from morbid obesity. Reduction of body weight before surgery is an important element. The aim of the study was to present the current knowledge on preoperative weight reduction and diet for this purpose.

MATERIAL AND METHODS

To achieve the aims of the paper, articles available in the PubMed / MEDLINE database published in 2005-2020 were used, as well as the guidelines of societies such as Metabolic and Bariatric Surgery Chapter of the Association of Polish Surgeons, American Association of Clinical Endocrinologists, The Obesity Society and American Society for Metabolic &amp; Bariatric Surgery, International Federation for Surgery of Obesity and Metabolic Disorders-European Chapter and European Association for the Study of Obesity.

RESULTS

Studies show that even a modest reduction in weight in the early preoperative period facilitates surgery and reduces the number of complications. The available data do not support the effect of preoperative weight loss on increased postoperative weight loss. The use of balanced, energy-restricted diet in the preoperative period prepares the patient for changes in the way of nutrition, which improves the nutritional status of patient. Low calorie (LCD) or very low calorie (VLCD) diet can be an effective method of weight loss before surgery, however, this approach does not allow to modify eating habits. The use of a very low calorie ketogenic diet (VLCKD) remains under discussion.

CONCLUSIONS

There is a need for large randomized trials to assess short and long term benefits of preoperative weight loss and methods of weight loss among patients qualified for bariatric surgery, also the standardization of nutritional management in the preoperative period.

Developing Integrated Clinical Pathways for the Management of Clinically Severe Adult Obesity: a Critique of NHS England Policy

PURPOSE OF THE REVIEW

Pathways for obesity prevention and treatment are well documented, yet the prevalence of obesity is rising, and access to treatment (including bariatric surgery) is limited. This review seeks to assess the current integrated clinical pathway for obesity management in England and determine the major challenges.

RECENT FINDINGS

Evidence for tier 2 (community-based lifestyle intervention) and tier 3 (specialist weight management services) is limited, and how it facilitates care and improve outcomes in tier 4 remains uncertain. Treatment access, rigidity in pathways, uncertain treatment outcomes and weight stigma seems to be major barriers to improved care. More emphasis must be placed on access to effective treatments, treatment flexibility, addressing stigma and ensuring treatment efficacy including long-term health outcomes. Prevention and treatment should both receive significant focus though should be considered to be largely separate pathways. A simplified system for weight management is needed to allow flexibility and the delivery of personalized care including post-bariatric surgery care for those who need it.

Effectiveness of a Low-Calorie Diet for Liver Volume Reduction Prior to Bariatric Surgery: a Systematic Review

An energy-restricted diet is often prescribed before bariatric surgery to reduce weight and liver volume. While very-low-calorie diets (VLCDs, 450–800 kcal per day) have shown to be effective, the effectiveness of low-calorie diets (LCDs, 800–1500 kcal per day) is less obvious. The objective of this systematic review was to elucidate the effectiveness of LCD on liver volume reduction in patients awaiting bariatric surgery. Eight studies (n = 251) were included describing nine different diets (800–1200 kcal, 2–8 weeks). An LCD was effective in liver volume reduction (12–27%) and weight loss (4–17%), particularly during the first weeks. The LCD showed an acceptable patients’ compliance. Based on these findings, an LCD (800–1200 kcal), instead of a VLCD, for 2 to 4 weeks should be preferred.

Systematic review and meta-analysis of perioperative behavioral lifestyle and nutritional interventions in bariatric surgery: a call for better research and reporting

Bariatric surgery is considered the most effective treatment for people with morbid obesity, and certain interventions could enhance its long-term results. We searched MEDLINE, Embase, Web of Science, CENTRAL, and trial registers up to January 1, 2020. Randomized controlled trials, where behavioral lifestyle or nutritional interventions were provided perioperatively were included. Primary outcome was weight change. Two reviewers independently performed each stage of the review. Altogether 6652 references were screened. 31 studies were included for qualitative synthesis and 22 studies for quantitative synthesis. Interventions varied greatly, thus limiting possibility of synthesizing all results. Six groups of interventions were discerned, and we used standardized mean differences for synthesis. Low to very-low certainty evidence suggests that physical activity, nonvitamin nutritional interventions, vitamins, psychotherapy, and counseling but not combined interventions might bring some benefit regarding short-term postsurgery follow-ups (up to 12 mo), but the estimates varied and results were not statistically significant, except for 12 months follow-ups regarding counseling. Psychotherapy and counseling, but not vitamins and combined interventions, may provide some benefit at longer follow-ups (over 12 mo), but the certainty of evidence was low to very-low and statistically significant results were observed in comparisons including data from single studies with small sample sizes only. Included studies expressed an outcome "weight change" using 20 different measures. Misreporting of data and huge variety of outcomes do not benefit systematic analyses and may possibly lead to confusion of both researchers and readers. We suggest that authors follow a predefined set of outcomes when reporting the results of their studies. The initiative to produce "core outcome set" for clinical trials in bariatric surgery trials is currently underway.

Diet approach before and after bariatric surgery

Bariatric surgery (BS) is today the most effective therapy for inducing long-term weight loss and for reducing comorbidity burden and mortality in patients with severe obesity. On the other hand, BS may be associated to new clinical problems, complications and side effects, in particular in the nutritional domain. Therefore, the nutritional management of the bariatric patients requires specific nutritional skills. In this paper, a brief overview of the nutritional management of the bariatric patients will be provided from pre-operative to post-operative phase. Patients with severe obesity often display micronutrient deficiencies when compared to normal weight controls. Therefore, nutritional status should be checked in every patient and correction of deficiencies attempted before surgery. At present, evidences from randomized and retrospective studies do not support the hypothesis that pre-operative weight loss could improve weight loss after BS surgery, and the insurance-mandated policy of a preoperative weight loss as a pre-requisite for admission to surgery is not supported by medical evidence. On the contrary, some studies suggest that a modest weight loss of 5-10% in the immediate preoperative period could facilitate surgery and reduce the risk of complications. Very low calories diet (VLCD) and very low calories ketogenic diets (VLCKD) are the most frequently used methods for the induction of a pre-operative weight loss today. After surgery, nutritional counselling is recommended in order to facilitate the adaptation of the eating habits to the new gastro-intestinal physiology. Nutritional deficits may arise according to the type of bariatric procedure and they should be prevented, diagnosed and eventually treated. Finally, specific nutritional problems, like dumping syndrome and reactive hypoglycaemia, can occur and should be managed largely by nutritional manipulation. In conclusion, the nutritional management of the bariatric patients requires specific nutritional skills and the intervention of experienced nutritionists and dieticians.

Microbial Adaptation Due to Gastric Bypass Surgery: The Nutritional Impact

Bariatric surgery leads to sustained weight loss and the resolution of obesity-related comorbidities. Recent studies have suggested that changes in gut microbiota are associated with the weight loss induced by bariatric surgery. Several studies have observed major changes in the microbial composition following gastric bypass surgery. However, there are inconsistencies between the reported alterations in microbial compositions in different studies. Furthermore, it is well established that diet is an important factor shaping the composition and function of intestinal microbiota. However, most studies on gastric bypass have not assessed the impact of dietary intake on the microbiome composition in general, let alone the impact of restrictive diets prior to bariatric surgery, which are recommended for reducing liver fat content and size. Thus, the relative impact of bariatric surgery on weight loss and gut microbiota remains unclear. Therefore, this review aims to provide a deeper understanding of the current knowledge of the changes in intestinal microbiota induced by bariatric surgery considering pre-surgical nutritional changes.

Age-related outcomes in laparoscopic hiatal hernia repair: Is there a "too old" for antireflux surgery?

BACKGROUND

Minimally invasive antireflux surgery has been shown to be safe and effective for the treatment of gastroesophageal reflux (GERD) in elderly patients. However, there is a paucity of data on the influence of advanced age on long-term quality of life (QoL) and perioperative outcomes after laparoscopic antireflux surgery (LARS).

METHOD

A retrospective study of patients undergoing LARS between February 2012 and June 2018 at a single institution was conducted. Patients were divided into four age categories. Perioperative data and quality of life (QOL) outcomes were collected and analyzed.

RESULTS

A total of 492 patients, with mean follow-up of 21 months post surgery, were included in the final analysis. Patients were divided into four age-determined subgroups (< 50:75, 50-65:179, 65-75:144, ≥ 75:94). Advancing age was associated with increasing likelihood of comorbid disease. Older patients were significantly more likely to require Collis gastroplasty (OR 2.09), or concurrent gastropexy (OR 3.20). Older surgical patients also demonstrated increased operative time (ß 6.29, p < .001), length of hospital stay (ß 0.56, p < .001) in addition to increased likelihood of intraoperative complications (OR 2.94, p = .003) and reoperations (OR 2.36, p < .05). However, postoperative QoL outcomes and complication rates were parallel among all age groups.

CONCLUSIONS

Among older patients, there is a greater risk of intraoperative complications, reoperation rates as well as longer operative time and LOS after LARS. However, a long-term QoL benefit is demonstrated among elderly patients who have undergone this procedure. Rather than serving as an exclusion criterion for surgical intervention, advanced age among chronic reflux patients should instead represent a comorbidity addressed in the planning stages of LARS.

Impact of a preoperative low-calorie diet on liver histology in patients with fatty liver disease undergoing bariatric surgery

BACKGROUND

A low-calorie diet (LCD) before bariatric surgery has been shown to reduce liver volume and facilitate ease of operation. It is estimated that 75%-100% of individuals undergoing bariatric surgery have nonalcoholic fatty liver disease (NAFLD).

OBJECTIVES

We aimed to investigate how an LCD affects liver histology in the setting of NAFLD.

SETTING

University Hospital, United States.

METHODS

Forty intraoperative liver specimens were analyzed histologically as follows: 20 with and 20 without a preoperative 2-week, 1200 kcal/d LCD. Weight was measured prediet, at surgery, and 6 months after surgery. NAFLD activity score was used to grade liver histology at surgery. The NAFLD activity score scores steatosis, lobular inflammation, hepatocellular ballooning, and fibrosis.

RESULTS

The non-LCD group (n = 20) had mean weight at surgery of 136.1 ± 24.1 kg. The LCD group (n = 20) had initial mean weight of 128.6 ± 25.4 kg, with presurgical weight loss of 3.43 kg (range, 0-9.3 kg), mean change in body mass index 1.24 kg/m² (2.66% total weight loss) on an LCD. The LCD group had significantly less steatosis (P = .02), fewer foci of lobular inflammation (P = .01), and less hepatocellular ballooning (P = .04) compared with the non-LCD group; with no difference in degree of fibrosis. Fewer patients in the LCD group had nonalcoholic steatohepatitis with ballooning (P = .04). Weight loss on an LCD before bariatric surgery was predictive of weight loss 6 months after surgery (P = .026).

CONCLUSIONS

A 2-week LCD before bariatric surgery is associated with significant improvement in steatosis, inflammation, and hepatocellular ballooning in NAFLD. Among LCD patients, preoperative weight loss was associated with improved 6-month weight loss and liver function.

Effect of Thoracic Gas Volume Changes on Body Composition Assessed by Air Displacement Plethysmography after Rapid Weight Loss and Regain in Elite Collegiate Wrestlers

We investigated the effect of rapid weight loss (RWL) and weight regain (WR) on thoracic gas volume (V_TG) and body composition assessment using air displacement plethysmography (ADP) in male wrestlers. Eight male elite collegiate wrestlers completed a RWL regimen (6% of body mass) over a 53-h period, which was followed by a 13-h WR period. ADP was used at three time points (baseline (T1), post-RWL (T2) and post-WR (T3)) according to the manufacturer’s testing recommendations. The total body water and bone mineral content were estimated using the stable isotope dilution method and dual energy X-ray absorptiometry, respectively, at the same time points. Body composition was assessed with two-component (2C) or four-component (4C) models using either the measured V_TG (mV_TG) or predicted V_TG (pV_TG). Measured V_TG increased from T1 to T2 (0.36 ± 0.31 L, p < 0.05) and decreased from T2 to T3 (−0.29 ± 0.15 L, p < 0.01). However, the changes in fat mass and fat free mass, which were calculated by both 2C and 4C models, were not significantly different when compared between calculations using mV_TG and those using pV_TG. Our results indicate that V_TG significantly changes during RWL and WR, but both measured and predicted V_TG can be used to assess changes in body composition during RWL and WR.