Nonalcoholic fatty liver disease in severe obese patients, subjected to bariatric surgery

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.

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.

Impact of Preoperative Protein Sparing Modified Fast Diet on Bariatric Surgery

INTRODUCTION

Bariatric surgery can become technically challenging in the setting of liver steatosis and hepatomegaly. The protein sparing modified fast (PSMF) diet helps in achieving rapid weight loss. The aim of this study is to explore the results of a preoperative PSMF diet on liver volume and steatosis as well as on intraoperative and postoperative complications in patients with hepatomegaly undergoing Roux-en-Y gastric bypass (RYGB).

METHODS

Between January 2010 and January 2021, 713 patients undergoing RYGB as a primary bariatric surgery were divided in two groups. Those with a measured liver length above 16 cm and or evidence of liver steatosis on ultrasound (group 1) were offered a preoperative PSMF diet while the remaining (group 2) proceeded directly to surgery. Between January 2010 and April 2012, patients included in group 1 had liver volume measurements on magnetic resonance imaging the day before the diet was started and the day before the surgery. For the length of the study, intraoperative and postoperative data were recorded for both groups.

RESULTS

Five days of preoperative PSMF diet resulted in a significant reduction of total and left liver volume (15.8% and 21% respectively, p < 0.001). There was no difference in intraoperative bleeding and conversion rate or postoperative complication rate between both groups.

CONCLUSION

The PSMF diet helps in achieving a rapid decrease in liver volume. Patients with hepatomegaly initially thought to be at a higher risk of intraoperative complications reached comparable rates to patients without hepatomegaly after the diet regimen without any impact on the postoperative course.

Preoperative Weight Loss as a Predictor of Bariatric Surgery Postoperative Weight Loss and Complications

BACKGROUND

The association between preoperative weight loss and bariatric surgery outcomes remains unclear. We explored the utility of preoperative weight loss as a predictor of postoperative weight loss success. Additionally, we examined the association of preoperative weight loss with perioperative complication rates.

METHODS

Retrospective chart review of patients who underwent primary sleeve gastrectomy or primary Roux-en-Y gastric bypass for weight loss at a single institution between January 2003 and November 2017. Additional follow-up was obtained by a postoperative standardized patient questionnaire. Statistical analysis consisted of bivariate and multivariate logistic regression analysis.

RESULTS

Our study included 427 patients. Majority were female (n = 313, 73.3%) and underwent sleeve gastrectomy (n = 261, 61.1%). Average age was 45.6 years, and average follow-up was 6.3 years. Greater preoperative weight loss was associated with decreased length of stay (1.8 vs 1.3 days) in patients who underwent sleeve gastrectomy. Multivariable regression analysis revealed that preoperative weight loss was not associated with postoperative weight loss.

CONCLUSIONS

Preoperative weight loss is not predictive of postoperative weight loss success after bariatric surgery. Greater preoperative weight loss was associated with a mild decreased in length of stay but was not associated with a reduction in operative time, overall complication rates, ICU admissions, or intraoperative complications. The inconclusive literature and our findings do not support the medical necessity of weight loss prior to bariatric surgery for the purpose of reducing surgical complications or predicting successful postoperative weight loss success.

Effect of Phentermine on Hepatic Steatosis in Bariatric Surgery: A Pilot Study

OBJECTIVE

Hepatic steatosis is associated with increased surgical complications in bariatric surgery patients. We aimed to evaluate the effect of phentermine in reducing hepatic steatosis, adipose tissue, and surgical complications in patients undergoing bariatric surgery.

METHODS

This was a two-arm, double-blind, randomized, controlled pilot trial of 64 adult subjects with BMI >35 kg/m2 selected for bariatric surgery randomized into phentermine group (15 mg once daily) or placebo group for 8 weeks. Both groups adhered to a hypocaloric diet (500 calories/day) and an individualized exercise program. The primary endpoint was reducing the frequency of hepatic steatosis measured by ultrasound and reducing adipose tissue through fat mass in total kilograms or percentage. Key secondary points were the prevalence of surgical complications. Baseline and final biochemical parameters and blood pressure too were assessments.

RESULTS

In the phentermine group, the frequency of hepatic steatosis decreased by 19%, and the percentage of patients with a normal ultrasound increased from 9% to 28% (p = 0.05). Likewise, the decrease in fat mass in kilograms was more significant in the phentermine group (56.1 kg vs. 51.8 kg, p = 0.02). A significant reduction in the HOMA-IR index was observed regardless of weight loss. No differences in surgical complications were observed between groups. Phentermine was well-tolerated; no differences were observed in the frequency of adverse events between the groups.

CONCLUSIONS

Phentermine decreased the proportion of individuals with hepatic steatosis by 19% and promoted a more significant fat mass loss in kilograms among candidates for bariatric surgery.

Evaluation of thrombocytopenia in patients with non-alcoholic fatty liver disease without cirrhosis

INTRODUCTION AND OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder in western countries. It is often related to metabolic syndrome, presenting an increased risk of advanced liver disease and cardiovascular-related death. In some etiologies of chronic liver disease, thrombocytopenia has been associated not only with advanced stages of fibrosis but also with autoimmune disease. In NAFLD, however, its prevalence and related factors are still unknown. The aim of this study is to evaluate the prevalence of thrombocytopenia in NAFLD patients without cirrhosis and to investigate its related risk factors.

PATIENTS AND METHODS

This was a retrospective study carried out in two tertiary hospitals in the South and Southeast regions of Brazil. Patients diagnosed with NAFLD by liver biopsy were included. Those with other causes of liver disease and/or cirrhosis were excluded. For analysis, patients were divided into two groups, with and without thrombocytopenia. Data was analyzed using a significance level of 5%.

RESULTS

441 non-cirrhotic patients with NAFLD (evaluated by liver biopsy) were included in the study. The prevalence of thrombocytopenia was 3.2% (14/441 patients). In the comparative analysis between groups, thrombocytopenia was associated with male sex (p=0.007) and level of hemoglobin (p=0.023).

CONCLUSION

Thrombocytopenia is an infrequent event in NAFLD patients without cirrhosis and is related with male sex and higher hemoglobin levels.

Phase angle and non-alcoholic fatty liver disease before and after bariatric surgery

BACKGROUND

Obesity is a global health problem that is continuing to increase in the young population. In Brazil, the frequency of obesity in 2018 was 19.8%. Several comorbidities are directly associated with obesity, such as non-alcoholic fatty liver disease (NAFLD), which is considered the most common liver disorder in Western countries and affects up to 46% of adults. Bariatric surgery is effective in treating obesity and can improve NAFLD; however, the effect of bariatric surgery on body composition, phase angle (PA), and improving NAFLD needs to be further studied.

AIM

To analyze the PA in the postoperative period of bariatric surgery and to correlate it with changes in body composition and liver disease.

METHODS

This study is a retrospective cohort study of the analysis of the medical records of patients undergoing bariatric surgery in a reference center of a teaching hospital in Porto Alegre over a 2-year period. Patients older than 18 years whose record contained all information relevant to the study were included. The data analyzed were body composition and PA through electrical bioimpedance and NAFLD through liver biopsy in the pre- and postoperative period. The level of significance adopted for the statistical analyses was 5%.

RESULTS

We evaluated 379 patients with preoperative data. Regarding PA, 169 patients were analyzed, and 33 patients had liver biopsy pre- and postoperatively with NAFLD information. In total, 79.4% were female, with a mean age of 39.1 ± 10.6 years. The average body mass index (BMI) was 45.9 ± 7.5 kg/m². The PA showed a mean of 5.8 ± 0.62° in the preoperative period and a significant reduction in the postoperative period. A postoperative reduction in body composition data (skeletal muscle mass, fat percentage, fat mass, body cell mass, BMI and visceral fat area) was shown as well. Regarding liver disease, all patients presented a reduction in the degrees and stages of liver disease in the postoperative period, and some had no degree of liver disease at all.

CONCLUSION

PA decreased after bariatric surgery, with a direct correlation with weight loss and changes in body composition. The decrease in PA was not correlated with the improvement in NAFLD.

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.

Impact of Exercise on Body Composition and Cardiometabolic Risk Factors in Patients Awaiting Bariatric Surgery

BACKGROUND

The role of exercise to achieve weight reductions in patients awaiting bariatric surgery has been little studied. The aim of this study was to describe the effects of an exercise program on body composition and cardiometabolic risk factors in patients awaiting bariatric surgery.

METHODS

Twenty-three patients awaiting bariatric surgery were divided into two groups: (a) an exercise group (EG, n = 12) and (b) a control group (CG, n = 11). Both groups received the usual care prior to surgery, but the EG also performed a 12-week exercise program which combined endurance and resistance training. Body composition, cardiometabolic risk factors, physical fitness, basal metabolic rate, and quality of life were assessed at baseline and at the end of the study.

RESULTS

After the exercise program, the EG achieved significant reductions in total weight (- 7.3 ± 4.1 kg, P < 0.01), fat mass (- 7.1 ± 4.7 kg, P < 0.01), and waist circumference (- 5.3 ± 2.1 cm, P < 0.01), while they maintained their fat-free mass and basal metabolic rate levels. Only the EG showed reductions in HbA1c (- 0.4 ± 0.45%, P < 0.05), systolic (- 10.5 ± 12.7 mmHg), and diastolic blood pressure (- 3.9 ± 5.2 mmHg, P < 0.05), as well as a decrease in waist-to-height ratio (- 0.032 ± 0.12, P < 0.01) and an improvement in quality of life.

CONCLUSIONS

The implementation of an exercise program prior to bariatric surgery reduces fat mass and central obesity and improves cardiometabolic risk factors and quality of life, especially in the physical scales.

TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov (NCT03613766).

Performance of noninvasive scores for the diagnosis of advanced liver fibrosis in morbidly obese with nonalcoholic fatty liver disease

OBJECTIVES

Liver fibrosis is one of the most important predictors of mortality related to nonalcoholic fatty liver disease (NAFLD). The use of noninvasive markers has the advantage of a simple and low-cost evaluation. The aim of this study was to evaluate the performance of six noninvasive scores for the diagnosis of advanced liver fibrosis in morbidly obese patients.

MATERIAL AND METHODS

A retrospective study validation included 323 morbidly obese patients undergoing bariatric surgery. Advance fibrosis was defined as stage 3 and 4 (septal fibrosis or cirrhosis). Accuracy, sensitivity, specificity, positive (PPV) or negative (NPV) predictive value, and positive (PLR) or negative (NLR) likelihood ratio test of the following noninvasive liver fibrosis scores were evaluated: aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio (AAR); AST to platelet ratio index (APRI); BARD; FIB4, NAFLD fibrosis score (NFS) and BAAT, which were compared with the histological findings of the intraoperative liver biopsy. The cutoff points established in the validation studies were used: AAR  >  1; APRL  >  0.98; BARD  ≥  2; FIB4  >  2.67; NFS  >  0.676 and BAAT  >  1.

RESULTS

Twenty-nine patients (8.97%) presented advanced fibrosis. APRI presented the higher specificity (99.61%), PPV (85.71%), PLR (62.5) and accuracy (0.93). FIB4 was the second test in accuracy (0.9) and in PLR (10.53). BAAT presented the highest sensitivity (73.08%) and NPV (94.78%); NFS the lowest sensitivity (12,5%), and BARD the lowest accuracy (0.44).

CONCLUSION

APRI and FIB-4 were the tests with best performance to predict advanced fibrosis.

Dietary Management in the Immediate Preoperative Period of Bariatric Surgery: a National Overview : Bariatric Preoperative Diets

BACKGROUND

Although widely applied, there is no consensus about the characteristics of the diets prescribed in the immediate preoperative period of bariatric surgery (BS). The objective of this study was to perform a survey on preoperative dietary management in BS centers.

METHODS

This was a cross-sectional study with BS Brazilian centers. Only BS centers with certificate of excellence by Surgical Review Corporation were included. An electronic questionnaire was applied to assess details about the dietary management in the immediate preoperative period of BS.

RESULTS

Of the 15 centers invited, 80% (n = 12) answered the questionnaire. Preoperative weight loss was required to patients in all 12 centers. For 8.3% (n = 1), this request was applied to all patients; 91.7% (n = 11) of the centers requested weight loss in specific cases. Ten (83.3%) centers prescribed restrictive diets; none of these adopted a standard dietary protocol. The caloric value of the diets ranged from 800 to 2000 kcal/day. The duration of the diet ranged from 10 to 20 days in 40% (n = 4) of the centers and from 20 to 90 days in 60% (n = 6) of the centers. Dietary prescription was based on team consensus in 100% (n = 12) of the centers. In 33.3% (n = 4) of the centers, scientific evidence supporting dietary prescription was cited.

CONCLUSION

This study identified the frequent practice of requesting preoperative weight loss and the diversity of diets used in the immediate preoperative period by Brazilian BS centers. Future guideline proposal is needed on preoperative BS diets.

Monitoring of Liver Function Tests after Roux-en-Y Gastric Bypass: An Examination of Evidence Base

There is no consensus on the monitoring of liver function tests after Roux-en-Y gastric bypass (RYGB). Since the main objective of such monitoring would be to diagnose early those who will eventually develop liver failure after RYGB, we performed a systematic review on this topic. An extensive search of literature revealed only 10 such cases in 6 published articles. It would hence appear that liver failure is a rare problem after RYGB. Routine lifelong monitoring of liver function tests is therefore unnecessary for otherwise asymptomatic individuals. Such monitoring should hence be reserved for high-risk groups, such as patients with liver cirrhosis, those undergoing extended limb/distal RYGB, patients with new illnesses, those abusing alcohol, those on hepatotoxic drugs and those presenting with a surgical complication.

Preoperative Methods to Reduce Liver Volume in Bariatric Surgery: a Systematic Review

Background

Patients qualified for gastric bypass surgery have an enlarged and fatty liver. An essential step in gastric bypass surgery is elevation of the left liver lobe to expose the gastroesophageal junction. An enlarged and fatty liver complicates the surgical procedure and increases the risk for laceration of the liver. The aim of our study was to evaluate methods to reduce liver volume in patients prior to gastric bypass surgery.

Methods

A systematic literature search of multiple databases, including PubMed, EMBASE.com, and the Cochrane Library and a hand search of reference lists, was performed. We used the search terms morbid obesity and liver, including their synonyms and controlled terms. Inclusion criteria were as follows: patients with morbid obesity who qualified for bariatric surgery, the use of a preoperative treatment to reduce liver volume, and the use of imaging techniques before and after treatment.

Results

In total, 281 patients in 11 different studies were included. Preoperative diets reduced liver size by an average of 14 %, alternative methods including nutritional supplements, reduced liver size between 20 and 43 %, and an intragastric balloon by 32 %.

Conclusions

This review showed that nutritional supplements and intragastric balloon are more effective than low calorie diets in reducing liver volume prior to gastric bypass surgery. However, low calorie diet is the preferable method to reduce liver volume, considering the level of evidence and practical applicability. There is a need for well-designed randomized studies with sufficient power in order to confirm the effectiveness of preoperative methods to reduce liver volume.