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.

Background There are data on the safety of cancer surgery and the efficacy of preventive strategies on the prevention of postoperative symptomatic COVID-19 in these patients. But there is little such data for any elective surgery. The main objectives of this study were to examine the safety of bariatric surgery (BS) during the coronavirus disease 2019 (COVID-19) pandemic and to determine the efficacy of perioperative COVID-19 protective strategies on postoperative symptomatic COVID-19 rates. Methods We conducted an international cohort study to determine all-cause and COVID-19-specific 30-day morbidity and mortality of BS performed between 01/05/2020 and 31/10/2020. Results Four hundred ninety-nine surgeons from 185 centres in 42 countries provided data on 7704 patients. Elective primary BS (n = 7084) was associated with a 30-day morbidity of 6.76% (n = 479) and a 30-day mortality of 0.14% (n = 10). Emergency BS, revisional BS, insulin-treated type 2 diabetes, and untreated obstructive sleep apnoea were associated with increased complications on multivariable analysis. Forty-three patients developed symptomatic COVID-19 postoperatively, with a higher risk in non-whites. Preoperative self-isolation, preoperative testing for SARS-CoV-2, and surgery in institutions not concurrently treating COVID-19 patients did not reduce the incidence of postoperative COVID-19. Postoperative symptomatic COVID-19 was more likely if the surgery was performed during a COVID-19 peak in that country. Conclusions BS can be performed safely during the COVID-19 pandemic with appropriate perioperative protocols. There was no relationship between preoperative testing for COVID-19 and self-isolation with symptomatic postoperative COVID-19. The risk of postoperative COVID-19 risk was greater in non-whites or if BS was performed during a local peak.

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Summary Background Metabolic and bariatric surgery (MBS) is an effective treatment for adolescents with severe obesity. Objectives This study examined the safety of MBS in adolescents during the coronavirus disease 2019 (COVID‐19) pandemic. Methods This was a global, multicentre and observational cohort study of MBS performed between May 01, 2020, and October 10,2020, in 68 centres from 24 countries. Data collection included in‐hospital and 30‐day COVID‐19 and surgery‐specific morbidity/mortality. Results One hundred and seventy adolescent patients (mean age: 17.75 ± 1.30 years), mostly females (n = 122, 71.8%), underwent MBS during the study period. The mean pre‐operative weight and body mass index were 122.16 ± 15.92 kg and 43.7 ± 7.11 kg/m2, respectively. Although majority of patients had pre‐operative testing for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) (n = 146; 85.9%), only 42.4% (n = 72) of the patients were asked to self‐isolate pre‐operatively. Two patients developed symptomatic SARS‐CoV‐2 infection post‐operatively (1.2%). The overall complication rate was 5.3% (n = 9). There was no mortality in this cohort. Conclusions MBS in adolescents with obesity is safe during the COVID‐19 pandemic when performed within the context of local precautionary procedures (such as pre‐operative testing). The 30‐day morbidity rates were similar to those reported pre‐pandemic. These data will help facilitate the safe re‐introduction of MBS services for this group of patients.

Background: Weight loss outcomes after bariatric surgery are less favorable in super morbidly obese patients (BMI ≥50 kg/m 2). Non-response, either defined as insufficient weight loss or weight regain after initial successful weight loss, is a matter of serious concern in these patients. The primary banded Roux-en-Y gastric bypass has shown promising results regarding weight loss in the bariatric population. However, up to now, long-term comparative data about the banded and non-banded bypass in superobese patients is lacking. The aim of this study is to assess the added value of the banded Roux-en-Y gastric bypass in superobese patients on long-term weight loss outcomes. Methods: This single center study will evaluate superobese patients who receive a non-banded Roux-en-Y gastric bypass (NB-RYGB) and a banded Roux-en-Y gastric bypass (B-RYGB). Data from the NB-RYGB group will be collected in retrospect, while data from the B-RYGB group will be collected prospectively. When performing a B-RYGB, a 7.0-8.0 cm silastic ring (MiniMizer®) will be placed proximal to the gastrojejunostomy. The main outcomes of this study are weight loss and non-response during a 10 year follow-up period. Secondary outcomes are reduction of obesity related comorbidities and medication, (ring-related) morbidity and mortality, complications, re-operations, patient satisfaction and health-related quality of life. A total of 142 patients will be included in this study. Discussion: This study will help establish the clinical utility of the B-RYGB in superobese patients. Trial register: NL8093. Registered 15 October 2019-Retrospectively registered on the Dutch Registry of Clinical trials, www.trialregister.nl

Background As result of bariatric surgery, patients are susceptible to protein deficiency which can result in undesirable lean body mass (LBM) loss. Consumption of high-protein diets or supplements could counteract this, but evidence about the effect is scarce. This paper systematically reviewed the literature to determine the effect of additional protein intake (≥60 g/day) on LBM preservation in post-bariatric patients. Methods An electronic search of PubMed, EMBASE and the Cochrane Library was conducted. Studies were included if patients received a high-protein diet or protein supplements for at least one month, and LBM was assessed. The primary outcome was difference in mean LBM loss between the experimental (protein) and control group. Secondary outcomes were differences in body fat mass, total body water, body mass index and resting metabolic rate. Results Two of the five included studies (n = 223) showed that consumption of proteins resulted in significant LBM preservation. Only one study reported a significant difference in the reduction of body fat mass and resting metabolic rate in favour of a high-protein diet, but none of the studies showed a significant difference in total body water loss or body mass index change between the two groups. Conclusions This paper showed inconclusive evidence for LBM preservation due to protein supplementation or a high-protein diet in post-bariatric patients. This outcome might be subjected to certain limitations, including a lack of blinding and a low compliance rate reported in the included studies. More specific and personalized recommendations regarding protein intake may need to be established by high quality research. Studies investigating the quantity (g/day) and quality (whey, casein or soy) of proteins are also needed.

Background When performing a Roux-en-Y gastric bypass (RYGB), the gastroenterostomy can be constructed with a circular stapled or linear stapled technique. The size of the gastroenterostomy depends on the stapling method and this may affect weight loss outcomes. The aim of this study was to examine the impact of the stapling technique on weight loss outcomes after RYGB. Methods This is a nationwide population-based cohort study of patients that received a RYGB. Data were derived from the Dutch Audit of Treatment of Obesity. Primary outcome was the impact of stapling technique on the rate of non-response defined as significant weight regain (≥20% of a patients’ lost weight) 2–4 years post-surgery, after initial successful weight loss (≥20% total weight loss, TWL). Secondary outcomes were the rate of response, defined as successful weight loss (≥20% TWL) within 1.5 years post-surgery, the incidence of complications and the progression of comorbidities. Results In a cohort of 12,468 patients, non-response was equally distributed between both groups (circular 18.0% vs. linear 17.6%). No differences in response rate (circular 97.0% vs. linear 96.5%) or %TWL were observed up to 4 years post-surgery. Patients in the circular stapled group experienced more complications, specifically major bleedings (2.4% vs. 1.2%; p=0.002) within 30 days postoperatively. No differences were found in deteriorated comorbidities, neither in de novo developed comorbidities. Conclusion When comparing stapling technique in RYGB, weight loss outcomes did not differ during a 4-year follow-up period. The linear stapled gastroenterostomy could pose an advantage due to its lower complication rate. Graphical abstract

Background Development of obesity and obesity-related diseases, such as type 2 diabetes mellitus and nonalcoholic fatty liver disease (NAFLD), is associated with altered gut microbiota composition. The aim of this study is to investigate associations among dietary compounds, intestinal cell function, and gut microbiota composition. We hypothesize that dietary lipid intake is associated with Paneth cell and goblet cell properties that affect gut microbiota composition. Objective The primary objective of this study is to determine whether a difference in dietary intake is associated with a difference in intestinal mucin-2 expression and gut microbiota composition. Methods This is a single-center prospective study, including 1 obese group undergoing laparoscopic Roux-en-y gastric bypass and 2 lean control groups undergoing either laparoscopic cholecystectomy or upper gastrointestinal endoscopy (n=228). During laparoscopy, biopsies will be taken of visceral fat (omentum majus), liver, muscle tissue of the abdominal wall, and subcutaneous fat. In the obese group, a small segment of the jejunum will be collected for analysis, which will be compared with an endoscopically derived jejunal biopsy from the upper gastrointestinal endoscopy control group. Stool samples for microbiota profiling will be collected at baseline and 1 year after surgery. Primary outcomes are fecal microbiota composition and mucus characteristics. Secondary outcomes include Paneth cell phenotype, body weight, diet composition, glucose tolerance, resolution of comorbidities, and weight loss 1 year after surgery. Results This trial is currently open for recruitment. The anticipated completion date is December 2019. Conclusions The Diet-Induced Alteration of Microbiota and Development of Obesity, NAFLD, and Diabetes study will improve insight into the pathophysiology of obesity and its associated metabolic disorders. Better understanding of weight loss failure and weight regain following bariatric surgery might also behold new therapeutic opportunities for obesity and obesity-related comorbidities. Trial Registration Netherlands Trial Register NTR5660; https://www.trialregister.nl/trial/5540 (Archived by WebCite at http://www.webcitation.org/78l7jOZre) International Registered Report Identifier (IRRID) DERR1-10.2196/11553