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

Clinical implications of nutritional interventions reducing calories, a systematic scoping review

BACKGROUND & AIMS

Caloric restriction (CR) constitutes a dietary approach of (temporarily) reducing calorie intake thereby inducing resilience and resistance mechanisms and promoting health. While CR's feasibility and safety have been proven in human trials, its full benefits and translation to different study populations warrants further exploration.

METHODS

We here conducted a systematic scoping review adhering to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Our search resulted in 3745 individual records, of which 40 were included. We showed that all studies consistently demonstrated the feasibility and safety of CR-like interventions. The specific effects of nutritional preconditioning vary, further underscoring the need for carefully crafted strategies, according to the intended effect, patient population, and logistical limitations.

CONCLUSIONS

CR-like interventions (long-term CR or short-term fasting) are feasible in a broad range of patient populations. Whether it has clinical benefit, f.i. reducing treatment-induced side effects and enhancing therapy efficacy, has to be investigated further.

A Systematic Review and Meta-Analysis of the Effect of Caloric Restriction on Skeletal Muscle Mass in Individuals with, and without, Type 2 Diabetes

BACKGROUND

Severe caloric restriction interventions (such as very-low-calorie diets) are effective for inducing significant weight loss and remission of type 2 diabetes (T2DM). However, suggestions of associated significant muscle mass (MM) loss create apprehension regarding their widespread use. We conducted a systematic review and meta-analysis to provide a quantitative assessment of their effect on measures of MM in individuals with, or without, T2DM.

METHODS

EMBASE, Medline, Pubmed, CINAHL, CENTRAL and Google Scholar were systematically searched for studies involving caloric restriction interventions up to 900 kilocalories per day reporting any measure of MM, in addition to fat mass (FM) or body weight (BW).

RESULTS

Forty-nine studies were eligible for inclusion, involving 4785 participants. Individuals with T2DM experienced significant reductions in MM (WMD -2.88 kg, 95% CI: -3.54, -2.22; p < 0.0001), although this was significantly less than the reduction in FM (WMD -7.62 kg, 95% CI: -10.87, -4.37; p < 0.0001). A similar pattern was observed across studies involving individuals without T2DM. MM constituted approximately 25.5% of overall weight loss in individuals with T2DM, and 27.5% in individuals without T2DM. Subgroup analysis paradoxically revealed greater BW and FM reductions with less restrictive interventions.

CONCLUSIONS

Our review suggests that caloric restriction interventions up to 900 kilocalories per day are associated with a significant reduction in MM, albeit in the context of a significantly greater reduction in FM. Furthermore, MM constituted approximately a quarter of the total weight loss. Finally, our data support the use of less restrictive interventions, which appear to be more beneficial for BW and FM loss.

Can caloric restriction improve outcomes of elective surgeries?

Energy restriction (ER) is a nutrition method to reduce the amount of energy intake while maintaining adequate nutrition. In clinical medicine, applications of ER have been implicated in longevity, mortality, metabolic, immune, and psychological health. However, there are limited studies showing the clinical benefit of ER within the immediate surgical setting. A specific, clinically oriented summary of the potential applications of ER is needed to optimize surgery outcomes for patients. The purpose of this article is to examine how ER can be used for perioperative optimization to improve outcomes for the patient and surgeon. It will also explore how these outcomes can feasibly fit in with enhanced recovery after surgery protocols and can be used as a method for nutrition optimization in surgery. Despite evidence of caloric restriction improving outcomes in critically ill surgical patients, there is not enough evidence to conclude that ER, perioperatively across noncritically ill cohorts, improves postoperative morbidity and mortality in elective surgeries. Nevertheless, a contemporary account of how ER techniques may have a significant role in reducing risk factors of adverse surgical outcomes in this cohort, for example, by encouraging preoperative weight loss contributing to decreased operating times, is reviewed.

Effect of Preoperative Very Low-Calorie Diets on Hepatic Steatosis, Fibrosis, and Perioperative Outcomes of Bariatric Surgery

Introduction: Preoperative weight loss through a very low-calorie diet (VLCD) has been shown to reduce liver volume and technical difficulty in patients undergoing metabolic and bariatric surgery (MBS). However, the effect of preoperative VLCD on liver histology and other outcomes is not well demonstrated. Our study aimed to explore the effect of a 2-week preoperative VLCD, compared with no-dietary intervention, on hepatic steatosis, fibrosis, weight loss, and other postoperative outcomes of MBS. Materials and Methods: This retrospective study was conducted at the Chulalongkorn Bariatric and Metabolic Institute, King Chulalongkorn Memorial Hospital, Bangkok, Thailand. The medical records of patients with severe obesity (body mass index ≥50 kg/m2) attending the clinic from January 2005 to December 2020 were reviewed. Clinical data and laboratory investigations were collected at baseline and at each follow-up visit, up to 5 years postoperatively. Hepatic steatosis and fibrosis were assessed by liver biopsy intraoperatively. Results: A total of 181 patients were included in this study. Preoperative VLCD was prescribed in 65 patients (VLCD group) and 116 patients received their usual diet (control group). Mean preoperative weight loss was 9.1 ± 6.1 kg in the VLCD group versus 0.0 ± 0.0 kg in the control group (P = .000). The VLCD group had significantly less number of patients with moderate and severe liver steatosis from the liver biopsy specimens (16.2% versus 46.3%; P = .008). However, there was no significant difference in fibrosis grade between those with VLCD and control (≥F2-fibrosis; 2.7% versus 7.5%; P = .118). Moreover, preoperative VLCD could reduce operating time in patients who underwent both laparoscopic Roux-en-Y gastric bypass (LRYGB; VLCD 163.4 ± 38.2 minutes versus control 215.1 ± 67.4 minute, P = .000) and laparoscopic sleeve gastrectomy (LSG; VLCD 110.8 ± 20.0 minutes versus control 131.0 ± 38.1 minutes, P = .004). During the 5-year follow-up, there were a significant difference of HbA1C between the VLCD and the control group (coefficient: -0.24 with 95% confidence interval [CI]: -0.44 to -0.04, P = .019), particularly in patients who underwent LRYGB (Coefficient: -0.26 with 95% CI: -0.49 to -0.03, P = .028), but not LSG. However, long-term weight loss outcomes and other biochemical outcomes were not different between the VLCD and the control group. Conclusion: Preoperative VLCD was associated with reduced liver steatosis and operative time in patients who underwent LRYGB and LSG. Moreover, preoperative VLCD significantly decreased HbA1C during a 5-year follow-up period. Therefore, it should be considered in patients with severe obesity, who will undergo MBS.

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.

Do treats facilitate the interpretation of findings on caloric restriction?

Introduction

Food can build social bonds and enhance interpersonal relationships. An area of research perhaps at odds with food abundance, is caloric restriction (CR), intermittent fasting (IF) or short-term fasting (STF). We aimed to study the impact of offering treats on the audience during presentations on IF and STF and whether this impacted the audience's reception of the subject. The contradiction of the tempting nature of sharing brownies juxtaposed with the potential health benefits presented is a light-hearted subject in a world where nutritional intake and health outcomes are the object of intense academic discussion.

Objective

Investigate how treats influence hospital personnel interpretation of information presented on the potential benefits of CR, IF and STF.

Methods

This trial consists of a cross-sectional study (CSS) and a randomised controlled trial (RCT) conducted at three study centres. The CSS involved a survey administered to healthcare professionals to assess their knowledge, experience and willingness regarding IF and/or STF. In the RCT, brownies were randomly provided to healthcare staff attending a scientific meeting on restricting calories.

Results

135 participants were included in the CSS and 64 participants joined the randomised experiment. We found that the randomisation had no statistically significant effect. Only 2 out of 64 were aware of the irony of the provided treatment. In the CSS, participants most often cited the expected beneficial effects on their short-term and long-term health as important reasons for adhering to IF and/or STF. Perceiving fasting as beneficial was mostly influenced by knowledge on the topic and previously adhering to a fasting diet.

Discussion

In this light-hearted, holiday-inspired exploratory study, we found that providing your audience with treats does not influence participants' opinion of you or your research, even when it focuses on the benefits of reducing calorie intake. The recipients of the treat will remain critical of presented findings, and due to prior experiences will be receptive to the counterintuitive topic of fasting.

β-hydroxybutyrate: A crucial therapeutic target for diverse liver diseases

β-hydroxybutyrate (β-HB), the most abundant ketone body, is produced primarily in the liver and acts as a substitute energy fuel to provide energy to extrahepatic tissues in the event of hypoglycemia or glycogen depletion. We now have an improved understanding of β-HB as a signal molecule and epigenetic regulatory factor as a result of intensive research over the last ten years. Because β-HB regulates various physiological and pathological processes, it may have a potential role in the treatment of metabolic diseases. The liver is the most significant metabolic organ, and the part that β-HB plays in liver disorders is receiving increasing attention. In this review, we summarize the therapeutic effects of β-HB on liver diseases and its underlying mechanisms of action. Moreover, we explore the prospects of exogenous supplements and endogenous ketosis including fasting, caloric restriction (CR), ketogenic diet (KD), and exercise as adjuvant nutritional therapies to protect the liver from damage and provide insights and strategies for exploring the treatment of various liver diseases.

Gut Microbiota and Plasma Bile Acids Associated with Non-Alcoholic Fatty Liver Disease Resolution in Bariatric Surgery Patients

Bariatric surgery (BS) has several benefits, including resolution of non-alcoholic fatty liver disease (NAFLD) in many patients. However, a significant percentage of patients do not experience improvement in fatty liver after BS, and more than 10% develop new or worsening NAFLD features. Therefore, a question that remains unanswered is why some patients experience resolved NAFLD after BS and others do not. In this study, we investigated the fecal microbiota and plasma bile acids associated with NAFLD resolution in twelve morbidly obese patients undergoing BS, of whom six resolved their steatosis one year after surgery and another six did not. Results indicate that the hallmark of the gut microbiota in responder patients is a greater abundance of Bacteroides, Akkermansia, and several species of the Clostridia class (genera: Blautia, Faecalibacterium, Roseburia, Butyricicoccusa, and Clostridium), along with a decreased abundance of Actinomycetes/Bifidobacterium and Faecalicatena. NAFLD resolution was also associated with a sustained increase in primary bile acids (particularly non-conjugated), which likely results from a reduction in bacterial gut species capable of generating secondary bile acids. We conclude that there are specific changes in gut microbiota and plasma bile acids that could contribute to resolving NAFLD in BS patients. The knowledge acquired can help to design interventions with prebiotics and/or probiotics to promote a gut microbiome that favors NAFLD resolution.

Weight loss interventions and nonalcoholic fatty liver disease: Optimizing liver outcomes

The growth in prevalence of obesity, type 2 diabetes and nonalcoholic fatty liver disease (NAFLD) has become one of the most important global health challenges. The three chronic diseases are closely linked in their epidemiology and pathophysiology. Currently, weight loss is the most effective treatment for NAFLD (even in the minority of patients with NAFLD who do not have obesity) and is recommended in all national and international guidelines. Accumulating evidence has shown that weight loss, whether achieved by diet and lifestyle interventions, bariatric surgery or pharmacotherapy, can improve biomarkers of NAFLD, as well as prevent progression and, in some cases, reverse fibrosis. There is a dose dependency of weight loss with NAFLD improvement. Pharmacotherapy with antiobesity medications, alone or in combination with intensive lifestyle interventions or other weight-loss drugs, is closing the efficacy gap between diet and exercise and weight-loss surgery in efficacy at reversing obesity. Given the importance of providing effective weight-loss treatment to patients with NAFLD, weight management services need to be made increasingly available and embedded within hepatology services. This narrative review addresses the evidence that weight loss optimizes liver outcomes in people with NAFLD.

Perfluorooctanesulfonic Acid (PFOS) Thwarts the Beneficial Effects of Calorie Restriction and Metformin

A combination of calorie restriction (CR), dietary modification, and exercise is the recommended therapy to reverse obesity and nonalcoholic fatty liver disease. In the liver, CR shifts hepatic metabolism from lipid storage to lipid utilization pathways, such as AMP-activated protein kinase (AMPK). Perfluorooctanesulfonic acid (PFOS), a fluorosurfactant previously used in stain repellents and anti-stick materials, can increase hepatic lipids in mice following relatively low-dose exposures. To test the hypothesis that PFOS administration interferes with CR, adult male C57BL/6N mice were fed ad libitum or a 25% reduced calorie diet concomitant with either vehicle (water) or 100 μg PFOS/kg/day via oral gavage for 6 weeks. CR alone improved hepatic lipids and glucose tolerance. PFOS did not significantly alter CR-induced weight loss, white adipose tissue mass, or liver weight over 6 weeks. However, PFOS increased hepatic triglyceride accumulation, in both mice fed ad libitum and subjected to CR. This was associated with decreased phosphorylated AMPK expression in liver. Glucagon (100 nM) treatment induced glucose production in hepatocytes, which was further upregulated with PFOS (2.5 μM) co-treatment. Next, to explore whether the observed changes were related to AMPK signaling, HepG2 cells were treated with metformin or AICAR alone or in combination with PFOS (25 μM). PFOS interfered with glucose-lowering effects of metformin, and AICAR treatment partially impaired PFOS-induced increase in glucose production. In 3T3-L1 adipocytes, metformin was less effective with PFOS co-treatment. Overall, PFOS administration disrupted hepatic lipid and glucose homeostasis and interfered with beneficial glucose-lowering effects of CR and metformin.

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.