Exercise Training Is Associated With Treatment Response in Liver Fat Content by Magnetic Resonance Imaging Independent of Clinically Significant Body Weight Loss in Patients With Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

AMPED study: Protocol for a randomized controlled trial of different doses of aerobic exercise training

Recently renamed, metabolic dysfunction-associated steatotic liver disease remains a leading cause of chronic liver disease worldwide. Regular physical activity is recommended as a treatment for all with this condition because it is highly efficacious, especially when exercise training is undertaken with a specific goal in mind. Despite decades of research demonstrating exercise's efficacy, key questions remain about the mechanism of benefit and most efficacious dose, as well as the independent impact on liver histology. To answer these questions, we present the design of a 16-week randomized controlled clinical trial of 45 adults aged 18-69 years with metabolic dysfunction-associated steatohepatitis. The primary aim of this study is to better understand the dose required and mechanisms to explain how exercise impacts multiple clinical end points in metabolic dysfunction-associated steatohepatitis. The primary outcome is MRI-measured liver fat. Secondary outcomes include other biomarkers of liver fibroinflammation, liver histology, and mechanistic pathways, as well as cardiometabolic risk and quality of life. This is the first study to compare different doses of exercise training to determine if there is a differential impact on imaging and serum biomarkers as well as liver histology.

Histological improvements following energy restriction and exercise: The role of insulin resistance in resolution of MASH

BACKGROUND & AIMS

Metabolic-dysfunction associated steatohepatitis (MASH) is one of the most common liver diseases worldwide and is characterized by multi-tissue insulin resistance. The effects of a 10-month energy restriction and exercise intervention on liver histology, anthropometrics, plasma biochemistries, and insulin sensitivity were compared to standard of care (control) to understand mechanisms that support liver health improvements.

METHODS

Following medical diagnosis of MASH, subjects were randomized to treatment (n=16) or control (n=8). Liver fat (MRS), 18-hour plasma biochemical measurements, and isotopically-labeled hyperinsulinemic-euglycemic clamps were completed pre- and post-intervention. Body composition and cardiorespiratory fitness (VO2peak) were also measured mid-intervention. Treatment subjects were counseled to reduce energy intake and completed supervised, high-intensity interval training (3x/week) for 10 months. Control subjects continued physician-directed care.

RESULTS

Treatment induced significant (P<0.05) reductions in body weight, fat mass, and liver injury, while VO2peak (P<0.05) and fatty acid (NEFA) suppression (P=0.06) were improved. Both groups exhibited reductions in total energy intake, HbA1c, hepatic insulin resistance, and liver fat (P<0.05). Compared to control, treatment induced a two-fold increase in peripheral insulin sensitivity which was significantly related to higher VO2peak and resolution of liver disease, despite no group differences in peripheral insulin sensitivity.

CONCLUSIONS

Exercise and energy-restriction elicited significant and clinically-meaningful treatment effects on liver health, potentially driven by a redistribution of excess nutrients to skeletal muscle, thereby reducing hepatic nutrient toxicity. Clinical guidelines should emphasize the addition of aerobic exercise in lifestyle treatments for the greatest histologic benefit in individuals with advanced MASH.

CLINICAL TRIAL NUMBER

NCT03151798.

Exercise improves surrogate measures of liver histological response in metabolic dysfunction-associated steatotic liver disease

BACKGROUND AND AIMS

Exercise is recommended for the management of metabolic dysfunction-associated steatotic liver disease (MASLD), yet effects on liver histology remain unknown, especially without significant weight loss. We aimed to examine changes in surrogate measures of liver histological response with exercise training.

METHODS

We conducted a post hoc pooled analysis of three randomised controlled trials (duration: 12-20 weeks) comparing aerobic exercise interventions with controls. The primary outcome measure was a ≥30% relative reduction in (MRI-measured) liver fat, as a surrogate measure of liver histological response (the threshold necessary for fibrosis improvement). Secondary outcome measures were changes in other biomarkers of liver fibrosis, anthropometry, body composition and aerobic fitness.

RESULTS

Eighty-eight adults (exercise: 54, control: 34; male: 67%) were included with mean (SD) age 51 (11) years and body mass index 33.3 (5.2) kg/m2. Following the intervention, exercise had ~5-fold (OR [95%CI]: 4.86 [1.72, 13.8], p = .002) greater odds of ≥30% relative reduction in MRI-measured liver fat compared with control. This paralleled the improvements in anthropometry (waist and hip circumference reduction), body composition (body fat, visceral and subcutaneous adipose tissue) and aerobic fitness (V̇O2peak, ventilatory threshold and exercise capacity). Importantly, these effects were independent of clinically significant body weight loss (<3% body weight).

CONCLUSION

Exercise training led to clinically meaningful improvements in surrogate serum- and imaging-based measures of liver histological change, without clinically meaningful body weight reduction. These data reinforce the weight-neutral benefit of exercise training and suggest that aerobic training may improve liver fibrosis in patients with MASLD.

Management of Cardiovascular Risk in the Non-alcoholic Fatty Liver Disease Setting

Non-alcoholic fatty liver disease (NAFLD) is an overlooked and undetected pathology, which affects more than 32% of adults worldwide. NAFLD is becoming more common in Western industrialised countries, particularly in patients with central obesity, type 2 diabetes, dyslipidaemia and metabolic syndrome. Although NAFLD has traditionally been interpreted as a liver disease with a high risk of liver-related complications, NAFLD is an underappreciated and independent risk factor for atherosclerotic cardiovascular disease, which is the principal cause of death in patients with NAFLD. Treatment options to counteract both the progression and development of cardiovascular disease and NAFLD include lifestyle interventions, such as weight loss, increased physical activity and dietary modification, and optimal medical therapy of comorbid conditions; nevertheless, further studies are needed to define optimal treatment strategies for the prevention of both hepatic and cardiovascular complications of NAFLD.

Unlocking liver health: Can tackling myosteatosis spark remission in metabolic dysfunction-associated steatotic liver disease?

Myosteatosis is highly prevalent in metabolic dysfunction-associated steatotic liver disease (MASLD) and could reciprocally impact liver function. Decreasing muscle fat could be indirectly hepatoprotective in MASLD. We conducted a review to identify interventions reducing myosteatosis and their impact on liver function. Non-pharmacological interventions included diet (caloric restriction or lipid enrichment), bariatric surgery and physical activity. Caloric restriction in humans achieving a mean weight loss of 3% only reduces muscle fat. Lipid-enriched diet increases liver fat in human with no impact on muscle fat, except sphingomyelin-enriched diet which reduces both lipid contents exclusively in pre-clinical studies. Bariatric surgery, hybrid training (resistance exercise and electric stimulation) or whole-body vibration in human decrease both liver and muscle fat. Physical activity impacts both phenotypes by reducing local and systemic inflammation, enhancing insulin sensitivity and modulating the expression of key mediators of the muscle-liver-adipose tissue axis. The combination of diet and physical activity acts synergistically in liver, muscle and white adipose tissue, and further decrease muscle and liver fat. Several pharmacological interventions (patchouli alcohol, KBP-089, 2,4-dinitrophenol methyl ether, adipoRon and atglistatin) and food supplementation (vitamin D or resveratrol) improve liver and muscle phenotypes in pre-clinical studies by increasing fatty acid oxidation and anti-inflammatory properties. These interventions are effective in reducing myosteatosis in MASLD while addressing the liver disease itself. This review supports that disturbances in inter-organ crosstalk are key pathophysiological mechanisms involved in MASLD and myosteatosis pathogenesis. Focusing on the skeletal muscle might offer new therapeutic strategies to treat MASLD by modulating the interactions between liver and muscles.

A public health perspective on mitigating the global burden of chronic liver disease

Chronic liver disease is a significant global health problem. Epidemiological trends do not show improvement in chronic liver disease incidence but rather a shift in etiologies, with steatotic liver disease (SLD) from metabolic dysfunction and alcohol becoming increasingly important causes. Consequently, there is a pressing need to develop a comprehensive public health approach for SLD. To that end, we propose a public health framework for preventing and controlling SLD. The framework is anchored on evidence linking physical inactivity, unhealthy dietary patterns, alcohol use, and obesity with both incidence and progression of SLD. Guided by the framework, we review examples of federal/state-level, community-level, and individual-level interventions with the potential to address these determinants of SLD. Ultimately, mitigating SLD's burden requires primary risk factor reduction at multiple socioecological levels, by scaling up the World Health Organization's "best buys," in addition to developing and implementing SLD-specific control interventions.

Exercise training improves serum biomarkers of liver fibroinflammation in patients with metabolic dysfunction-associated steatohepatitis

BACKGROUND AND AIMS

Exercise training is recommended for all patients with metabolic dysfunction-associated steatotic liver disease and may reverse liver fibrosis. Whether exercise training improves liver fibrosis without body weight loss remains controversial. We further investigated this relationship using serum biomarkers of liver fibroinflammation in a post hoc analysis of an exercise trial where patients did not lose significant body weight.

METHODS

In the NASHFit trial, patients with metabolic dysfunction-associated steatohepatitis were randomized to receive either moderate-intensity aerobic exercise training or standard clinical care for 20 weeks. Mediterranean-informed dietary counselling was provided to each group. Change in serum biomarkers was measured and compared between the two groups.

RESULTS

Exercise training led to improvement in serum biomarkers of liver fibroinflammation, including (1) ≥17 IU/L reduction in alanine aminotransferase (ALT) in 53% of individuals in the exercise training group compared to 13% in the standard clinical care group (p < 0.001; mean reduction 24% vs. 10% respectively) and (2) improvement in CK18 (-61 vs. +71 ng/mL, p = 0.040). ALT improvement ≥17 IU/L was correlated with ≥30% relative reduction in magnetic resonance imaging-measured liver fat and PNPLA3 genotype.

CONCLUSION

Exercise training improves multiple serum biomarkers of liver fibroinflammation at clinically significant thresholds of response without body weight loss. This study provides further evidence that exercise training should be viewed as a weight-neutral intervention for which response to intervention can be readily monitored with widely available non-invasive biomarkers that can be applied at the population level.

What Is New in Metabolic Dysfunction-Associated Steatotic Liver Disease in Lean Individuals: From Bench to Bedside

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects more than 30% of the world's adult population. While it is associated with obesity and metabolic syndrome, emerging evidence has shown that a substantial number of MASLD patients have a normal body mass index ("lean individuals with MASLD"). In this article, we provide an overview of the definition, epidemiology, pathogenesis, and clinical outcomes associated with lean individuals with MASLD and updates on current management.

Cdo1-Camkk2-AMPK axis confers the protective effects of exercise against NAFLD in mice

Exercise is an effective non-pharmacological strategy for ameliorating nonalcoholic fatty liver disease (NAFLD), but the underlying mechanism needs further investigation. Cysteine dioxygenase type 1 (Cdo1) is a key enzyme for cysteine catabolism that is enriched in liver, whose role in NAFLD remains poorly understood. Here, we show that exercise induces the expression of hepatic Cdo1 via the cAMP/PKA/CREB signaling pathway. Hepatocyte-specific knockout of Cdo1 (Cdo1LKO) decreases basal metabolic rate of the mice and impairs the effect of exercise against NAFLD, whereas hepatocyte-specific overexpression of Cdo1 (Cdo1LTG) increases basal metabolic rate of the mice and synergizes with exercise to ameliorate NAFLD. Mechanistically, Cdo1 tethers Camkk2 to AMPK by interacting with both of them, thereby activating AMPK signaling. This promotes fatty acid oxidation and mitochondrial biogenesis in hepatocytes to attenuate hepatosteatosis. Therefore, by promoting hepatic Camkk2-AMPK signaling pathway, Cdo1 acts as an important downstream effector of exercise to combat against NAFLD.

Exercise in the Management of Metabolic-Associated Fatty Liver Disease (MAFLD) in Adults: A Position Statement from Exercise and Sport Science Australia

Metabolic-associated fatty liver disease (MAFLD) is the most prevalent chronic liver disease worldwide, affecting 25% of people globally and up to 80% of people with obesity. MAFLD is characterised by fat accumulation in the liver (hepatic steatosis) with varying degrees of inflammation and fibrosis. MAFLD is strongly linked with cardiometabolic disease and lifestyle-related cancers, in addition to heightened liver-related morbidity and mortality. This position statement examines evidence for exercise in the management of MAFLD and describes the role of the exercise professional in the context of the multi-disciplinary care team. The purpose of these guidelines is to equip the exercise professional with a broad understanding of the pathophysiological underpinnings of MAFLD, how it is diagnosed and managed in clinical practice, and to provide evidence- and consensus-based recommendations for exercise therapy in MAFLD management. The majority of research evidence indicates that 150-240 min per week of at least moderate-intensity aerobic exercise can reduce hepatic steatosis by ~ 2-4% (absolute reduction), but as little as 135 min/week has been shown to be effective. While emerging evidence shows that high-intensity interval training (HIIT) approaches may provide comparable benefit on hepatic steatosis, there does not appear to be an intensity-dependent benefit, as long as the recommended exercise volume is achieved. This dose of exercise is likely to also reduce central adiposity, increase cardiorespiratory fitness and improve cardiometabolic health, irrespective of weight loss. Resistance training should be considered in addition to, and not instead of, aerobic exercise targets. The information in this statement is relevant and appropriate for people living with the condition historically termed non-alcoholic fatty liver disease (NAFLD), regardless of terminology.

Intra-gastric balloon with lifestyle modification: a promising therapeutic option for overweight and obese patients with metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Data on effects of intra-gastric balloon (IGB) on metabolic dysfunction-associated steatotic liver disease (MASLD) are scarce, in part with contradictory results, and mainly obtained in tertiary care patients with diabetes and other comorbidities. We here explore effects of IGB in patients with MASLD referred to a first-line obesity clinic.

METHODS

In this prospective cohort study, patients with at least significant fibrosis (≥ F2) and/or severe steatosis (S3) according to screening transient elastography (FibroScan®) were offered a second FibroScan® after 6 months lifestyle modification with or without IGB (based on patient preference).

RESULTS

50 of 100 consecutively screened patients (generally non-diabetic) qualified for repeated evaluation and 29 (58%) of those had a second FibroScan®. At baseline, at least significant fibrosis was present in 28% and severe steatosis in 91%. IGB was placed in 19 patients (59%), whereas 10 patients (41%) preferred only lifestyle modification (no differences in baseline characteristics between both groups). After 6 months, liver stiffness decreased markedly in the IGB group (median: from 6.0 to 4.9 kPa, p = 0.005), but not in the lifestyle modification only group (median: from 5.5 to 6.9 kPa, p = 0.477). Steatosis improved in both groups, (controlled attenuation parameter values; IGB, mean ± SD: from 328 ± 34 to 272 ± 62 dB/m, p = 0.006: lifestyle modification only, mean ± SD: from 344 ± 33 to 305 ± 43 dB/m: p = 0.006).

CONCLUSION

Both steatosis and fibrosis improve markedly in overweight/obese patients with MASLD after 6 months IGB combined with lifestyle modification. Our results warrant further research into long-term effect of IGB in these patients.

Practice patterns and considerations in liver transplantation from living donors with high BMI: A review

Living Donor Liver Transplantation (LDLT) is a valuable solution to the shortage of donor organs for patients with end-stage liver disease. However, the eligibility of obese donors for LDLT remains a subject of debate. This literature review explores global practices and perceptions of LDLT, identifies donor eligibility criteria, and discusses special considerations and ethical caveats. The review highlights the need for standardized guidelines for donor selection, considering the global distribution of Body mass index and variations in population-specific criteria. It also emphasizes the importance of non-invasive testing and pre-operative optimization of liver steatosis for select obese donors. Furthermore, the review examines the outcomes and complications associated with obese donors in LDLT. The findings of this review contribute to the ongoing discussion on the inclusion of obese donors in LDLT and provide insights for future research and guideline development.

Physical Activity and Nonalcoholic Fatty Liver Disease: A Roundtable Statement from the American College of Sports Medicine

ABSTRACT

Although physical activity (PA) is crucial in the prevention and clinical management of nonalcoholic fatty liver disease, most individuals with this chronic disease are inactive and do not achieve recommended amounts of PA. There is a robust and consistent body of evidence highlighting the benefit of participating in regular PA, including a reduction in liver fat and improvement in body composition, cardiorespiratory fitness, vascular biology, and health-related quality of life. Importantly, the benefits of regular PA can be seen without clinically significant weight loss. At least 150 min of moderate or 75 min of vigorous intensity PA are recommended weekly for all patients with nonalcoholic fatty liver disease, including those with compensated cirrhosis. If a formal exercise training program is prescribed, aerobic exercise with the addition of resistance training is preferred. In this roundtable document, the benefits of PA are discussed, along with recommendations for 1) PA assessment and screening; 2) how best to advise, counsel, and prescribe regular PA; and 3) when to refer to an exercise specialist.

Aerobic exercise and vitamin E improve high-fat diet-induced NAFLD in rats by regulating the AMPK pathway and oxidative stress

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) has emerged as a major chronic liver disease. We explored simple and effective ways to improve NAFLD and investigate the mechanism of action.

METHODS

NAFLD was induced in 40 rats fed a high-fat diet (HFD). Magnetic resonance imaging was used to evaluate the progression and improvement of NAFLD. The treatment-related interventions included aerobic exercise (E) and vitamin E (VE) supplementation. Expression levels of proteins related to fat metabolism were also assessed. The activities of antioxidant enzymes in the liver and serum lipid metabolism were analyzed using biochemical methods.

RESULTS

Aerobic exercise and vitamin E effectively improved NAFLD in rats, resulting in decreased hepatic fat accumulation, reduced hepatocyte ballooning, and decreased triglyceride levels. Combination therapy achieved the best effect. Both aerobic exercise and vitamin E activate the AMPK pathway to phosphorylate acetyl-CoA carboxylase (ACC) and reduce fatty acid synthesis. The expression of sterol regulatory element-binding protein-1 (SREBP-1) was decreased significantly in the treated groups, particularly in the E + VE + HFD group. The expression of carnitine palmitoyl-transferase 1C (CPT1C) significantly increased in the treated groups, particularly in the E + VE + HFD group. Compared with the control group, reactive oxygen species (ROS) in the E + HFD group were slightly decreased, while that in the VE + HFD group were significantly decreased, with the even greater reduction observed in the E + VE + HFD group.

CONCLUSION

Aerobic exercise and vitamin E supplementation can improve HFD-induced NAFLD in rats by regulating the AMPK pathway and reducing oxidative stress.

The heterogeneity of metabolic syndrome presentation and challenges this causes in its pharmacological management: a narrative review focusing on principal risk modifiers

INTRODUCTION

Metabolic syndrome (MetS), i.e. the cluster of cardiometabolic risk factors comprising visceral obesity, impaired glucose metabolism, arterial hypertension and atherogenic dyslipidemia, is prevalent globally and exacts a heavy toll on health care expenditures.

AREAS COVERED

The pathophenotypes of individual traits of the MetS in adults are discussed first, with strong emphasis on nonalcoholic fatty liver disease (NAFLD) and sex differences. Next, I discuss recent studies on phenotypic and outcome heterogeneity of the MetS, highlighting the role of NAFLD, sex, reproductive status, and depressive disorders. In the second half of the article, the therapeutic implications of the variable MetS types and features are analyzed, focusing on the most recent developments, and guidelines.

EXPERT OPINION

I have identified physiological, pathological, social and medical sources of phenotypical heterogeneity in the MetS and its constitutive traits. Improved understanding of these variables may be utilized in the setting of future precision medicine approaches in the field of metabolic disorders and target organ damage.

Innovative Therapeutic Approaches in Non-Alcoholic Fatty Liver Disease: When Knowing Your Patient Is Key

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disorders ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Hepatic steatosis may result from the dysfunction of multiple pathways and thus multiple molecular triggers involved in the disease have been described. The development of NASH entails the activation of inflammatory and fibrotic processes. Furthermore, NAFLD is also strongly associated with several extra-hepatic comorbidities, i.e., metabolic syndrome, type 2 diabetes mellitus, obesity, hypertension, cardiovascular disease and chronic kidney disease. Due to the heterogeneity of NAFLD presentations and the multifactorial etiology of the disease, clinical trials for NAFLD treatment are testing a wide range of interventions and drugs, with little success. Here, we propose a narrative review of the different phenotypic characteristics of NAFLD patients, whose disease may be triggered by different agents and driven along different pathophysiological pathways. Thus, correct phenotyping of NAFLD patients and personalized treatment is an innovative therapeutic approach that may lead to better therapeutic outcomes.

Exercise Is Medicine for Nonalcoholic Fatty Liver Disease: Exploration of Putative Mechanisms

Exercise remains a key component of nonalcoholic fatty liver disease (NAFLD) treatment. The mechanisms that underpin improvements in NAFLD remain the focus of much exploration in our attempt to better understand how exercise benefits patients with NAFLD. In this review, we summarize the available scientific literature in terms of mechanistic studies which explore the role of exercise training in modulating fatty acid metabolism, reducing hepatic inflammation, and improving liver fibrosis. This review highlights that beyond simple energy expenditure, the activation of key receptors and pathways may influence the degree of NAFLD-related improvements with some pathways being sensitive to exercise type, intensity, and volume. Importantly, each therapeutic target of exercise training in this review is also the focus of previous or ongoing drug development studies in patients with nonalcoholic steatohepatitis (NASH), and even when a regulatory-agency-approved drug comes to market, exercise will likely remain an integral component in the clinical management of patients with NAFLD and NASH.

American College of Sports Medicine (ACSM) International Multidisciplinary Roundtable report on physical activity and nonalcoholic fatty liver disease

BACKGROUND AND AIMS

We present findings from the inaugural American College of Sports Medicine (ACSM) International Multidisciplinary Roundtable, which was convened to evaluate the evidence for physical activity as a means of preventing or modifying the course of NAFLD.

APPROACH AND RESULTS

A scoping review was conducted to map the scientific literature and identify key concepts, research gaps, and evidence available to inform clinical practice, policymaking, and research. The scientific evidence demonstrated regular physical activity is associated with decreased risk of NAFLD development. Low physical activity is associated with a greater risk for disease progression and extrahepatic cancer. During routine health care visits, all patients with NAFLD should be screened for and counseled about physical activity benefits, including reduction in liver fat and improvement in body composition, fitness, and quality of life. While most physical activity benefits occur without clinically significant weight loss, evidence remains limited regarding the association between physical activity and liver fibrosis. At least 150 min/wk of moderate or 75 min/wk of vigorous-intensity physical activity are recommended for all patients with NAFLD. If a formal exercise training program is prescribed, aerobic exercise with the addition of resistance training is preferred.

CONCLUSIONS

The panel found consistent and compelling evidence that regular physical activity plays an important role in preventing NAFLD and improving intermediate clinical outcomes. Health care, fitness, and public health professionals are strongly encouraged to disseminate the information in this report. Future research should prioritize determining optimal strategies for promoting physical activity among individuals at risk and in those already diagnosed with NAFLD.