The effect of exercise training on intrahepatic triglyceride and hepatic insulin sensitivity: a systematic review and meta-analysis

Greater hepatic lipid saturation is associated with impaired glycaemic regulation in men with metabolic dysfunction-associated steatotic liver disease but is not altered by 6 weeks of exercise training

AIMS

To examine the impact of impaired glycaemic regulation (IGR) and exercise training on hepatic lipid composition in men with metabolic dysfunction-associated steatotic liver disease (MASLD).

MATERIALS AND METHODS

In Part A (cross-sectional design), 40 men with MASLD (liver proton density fat fraction [PDFF] ≥5.56%) were recruited to one of two groups: (1) normal glycaemic regulation (NGR) group (glycated haemoglobin [HbA1c] < 42 mmol∙mol-1 [<6.0%]; n = 14) or (2) IGR group (HbA1c ≥ 42 mmol∙mol-1 [≥6.0%]; n = 26). In Part B (randomized controlled trial design), participants in the IGR group were randomized to one of two 6-week interventions: (1) exercise training (EX; 70%-75% maximum heart rate; four sessions/week; n = 13) or (2) non-exercise control (CON; n = 13). Saturated (SI; primary outcome), unsaturated (UI) and polyunsaturated (PUI) hepatic lipid indices were determined using proton magnetic resonance spectroscopy. Additional secondary outcomes included liver PDFF, HbA1c, fasting plasma glucose (FPG), homeostatic model assessment of insulin resistance (HOMA-IR), peak oxygen uptake (VO2 peak), and plasma cytokeratin-18 (CK18) M65, among others.

RESULTS

In Part A, hepatic SI was higher and hepatic UI was lower in the IGR versus the NGR group (p = 0.038), and this hepatic lipid profile was associated with higher HbA1c levels, FPG levels, HOMA-IR and plasma CK18 M65 levels (rs ≥0.320). In Part B, hepatic lipid composition and liver PDFF were unchanged after EX versus CON (p ≥ 0.257), while FPG was reduced and VO2 peak was increased (p ≤ 0.030). ΔVO2 peak was inversely associated with Δhepatic SI (r = -0.433) and positively associated with Δhepatic UI and Δhepatic PUI (r ≥ 0.433).

CONCLUSIONS

Impaired glycaemic regulation in MASLD is characterized by greater hepatic lipid saturation; however, this composition is not altered by 6 weeks of moderate-intensity exercise training.

Association of physical activity and sports participation with insulin resistance and non-alcoholic fatty liver disease in people with type 1 diabetes

AIM

To evaluate the association between physical activity (PA) and sports participation with insulin resistance and non-alcoholic fatty liver disease (NAFLD) in people with type 1 diabetes (T1D).

METHODS

People with T1D from a secondary and tertiary care centre were included. Questionnaire-derived PA was expressed in metabolic equivalent of task hours per week (METh/week). Insulin sensitivity was calculated with the estimated glucose disposal rate (eGDR). NAFLD was assessed by transient elastography (TE). Multivariate linear and logistic regression models were conducted, adjusted for age, sex, diabetes duration and BMI.

RESULTS

In total, 254 participants were included (men 56%, age 44 ± 14 years, diabetes duration 24 ± 14 years, median BMI 24.8 kg/m2), of which 150 participants underwent TE. Total PA (median 50.7 METh/week) was not significantly associated with insulin resistance (median eGDR 7.31 mg/kg/min) (beta -0.00, 95% CI -0.01 to 0.00) or with NAFLD (OR 1.00, 95% CI 0.99-1.01). Participating in sports was significantly associated with eGDR (beta 0.94, 95% CI 0.48-1.41) and with NAFLD (OR 0.21, 95% CI 0.08-0.56).

CONCLUSIONS

In our T1D population, we could not find any dose-dependent association between PA, insulin resistance and NAFLD. People participating in sports had a lower degree of insulin resistance and lower odds for NAFLD.

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.

Physical exercise in liver diseases

Liver diseases contribute to ~2 million deaths each year and account for 4% of all deaths globally. Despite various treatment options, the management of liver diseases remains challenging. Physical exercise is a promising nonpharmacological approach to maintain and restore homeostasis and effectively prevent and mitigate liver diseases. In this review, we delve into the mechanisms of physical exercise in preventing and treating liver diseases, highlighting its effects on improving insulin sensitivity, regulating lipid homeostasis, and modulating immune function. In addition, we evaluate the impact of physical exercise on various liver diseases, including liver ischemia/reperfusion injury, cardiogenic liver disease, metabolic dysfunction-associated steatotic liver disease, portal hypertension, cirrhosis, and liver cancer. In conclusion, the review underscores the effectiveness of physical exercise as a beneficial intervention in combating liver diseases.

Role of lifestyle and glucagon-like peptide-1 receptor agonists for weight loss in obesity, type 2 diabetes and steatotic liver diseases

BACKGROUND

The current obesity pandemic has given rise to associated comorbidities and complications, including type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD). During the last decade, certain glucagon-like peptide 1 receptor agonists (GLP-1RA), originally developed as antihyperglycemic drugs, also demonstrated efficacy for weight loss.

AIMS

To review shared pathophysiologic features of common metabolic diseases and compare therapeutic strategies to reduce body weight and related complications.

METHODS

We performed an extensive literature research to describe the effects of lifestyle modification, first-generation anti-obesity drugs, and GLP-1RA on weight loss in humans with obesity, type 2 diabetes and MASLD.

RESULTS

Until recently, treatment of obesity has been limited to lifestyle modification, which offer moderate degree and sustainability of weight loss. The few approved first-generation anti-obesity drugs are either limited to short term use or to certain forms of obesity. Some GLP-1RA significantly decrease caloric intake and body weight. Liraglutide and semaglutide have therefore been approved for treating people with obesity. They also lead to a reduction of hepatic fat content and inflammation in people with biopsy-confirmed MASLD. Possible limitations comprise adverse effects, treatment adherence and persistence.

CONCLUSION

Certain GLP-1RA are superior to lifestyle modification and first-generation anti-obesity drugs in inducing weight loss. They have therefore markedly changed the portfolio of obesity treatment with additional beneficial effects on steatotic liver disease.

Strength Training Protects High-Fat-Fed Ovariectomized Mice against Insulin Resistance and Hepatic Steatosis

Menopause is characterized by a reduction in sex hormones in women and is associated with metabolic changes, including fatty liver and insulin resistance. Lifestyle changes, including a balanced diet and physical exercise, are necessary to prevent these undesirable changes. Strength training (ST) has been widely used because of the muscle and metabolic benefits it provides. Our study aims to evaluate the effects of ST on hepatic steatosis and insulin resistance in ovariectomized mice fed a high-fat diet (HFD) divided into four groups as follows: simulated sedentary surgery (SHAM-SED), trained simulated surgery (SHAM-EXE), sedentary ovariectomy (OVX-SED), and trained ovariectomy (OVX-EXE). They were fed an HFD for 9 weeks. ST was performed thrice a week. ST efficiently reduced body weight and fat percentage and increased lean mass in OVX mice. Furthermore, ST reduced the accumulation of ectopic hepatic lipids, increased AMPK phosphorylation, and inhibited the de novo lipogenesis pathway. OVX-EXE mice also showed a better glycemic profile, associated with greater insulin sensitivity identified by the euglycemic-hyperinsulinemic clamp, and reduced markers of hepatic oxidative stress compared with sedentary animals. Our data support the idea that ST can be indicated as a non-pharmacological treatment approach to mitigate metabolic changes resulting from menopause.

Exercise induces tissue-specific adaptations to enhance cardiometabolic health

The risk associated with multiple cancers, cardiovascular disease, diabetes, and all-cause mortality is decreased in individuals who meet the current recommendations for physical activity. Therefore, regular exercise remains a cornerstone in the prevention and treatment of non-communicable diseases. An acute bout of exercise results in the coordinated interaction between multiple tissues to meet the increased energy demand of exercise. Over time, the associated metabolic stress of each individual exercise bout provides the basis for long-term adaptations across tissues, including the cardiovascular system, skeletal muscle, adipose tissue, liver, pancreas, gut, and brain. Therefore, regular exercise is associated with a plethora of benefits throughout the whole body, including improved cardiorespiratory fitness, physical function, and glycemic control. Overall, we summarize the exercise-induced adaptations that occur within multiple tissues and how they converge to ultimately improve cardiometabolic health.

4. Comprehensive Medical Evaluation and Assessment of Comorbidities: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

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.

Lifestyle interventions in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a dynamic chronic liver disease that develops in close association with metabolic irregularities. Between 2016 and 2019, the global prevalence among adults was reported as 38% and among children and adolescents it was about 10%. NAFLD can be progressive and is associated with increased mortality from cardiovascular disease, extrahepatic cancers and liver complications. Despite these numerous adverse outcomes, no pharmacological treatments currently exist to treat nonalcoholic steatohepatitis, the progressive form of NAFLD. Therefore, the main treatment is the pursuit of a healthy lifestyle for both children and adults, which includes a diet rich in fruits, nuts, seeds, whole grains, fish and chicken and avoiding overconsumption of ultra-processed food, red meat, sugar-sweetened beverages and foods cooked at high heat. Physical activity at a level where one can talk but not sing is also recommended, including leisure-time activities and structured exercise. Avoidance of smoking and alcohol is also recommended. Policy-makers, community and school leaders need to work together to make their environments healthy by developing walkable and safe spaces with food stores stocked with culturally appropriate and healthy food items at affordable prices as well as providing age-appropriate and safe play areas in both schools and neighbourhoods.

Metabolic-Dysfunction-Associated Steatotic Liver Disease-Its Pathophysiology, Association with Atherosclerosis and Cardiovascular Disease, and Treatments

Metabolic-dysfunction-associated steatotic liver disease (MASLD) is a chronic liver disease that affects more than a quarter of the global population and whose prevalence is increasing worldwide due to the pandemic of obesity. Obesity, impaired glucose metabolism, high blood pressure and atherogenic dyslipidemia are risk factors for MASLD. Therefore, insulin resistance may be closely associated with the development and progression of MASLD. Hepatic entry of increased fatty acids released from adipose tissue, increase in fatty acid synthesis and reduced fatty acid oxidation in the liver and hepatic overproduction of triglyceride-rich lipoproteins may induce the development of MASLD. Since insulin resistance also induces atherosclerosis, the leading cause for death in MASLD patients is cardiovascular disease. Considering that the development of cardiovascular diseases determines the prognosis of MASLD patients, the therapeutic interventions for MASLD should reduce body weight and improve coronary risk factors, in addition to an improving in liver function. Lifestyle modifications, such as improved diet and increased exercise, and surgical interventions, such as bariatric surgery and intragastric balloons, have shown to improve MASLD by reducing body weight. Sodium glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been shown to improve coronary risk factors and to suppress the occurrence of cardiovascular diseases. Both SGLT2i and GLP-1 have been reported to improve liver enzymes, hepatic steatosis and fibrosis. We recently reported that the selective peroxisome proliferator-activated receptor-alpha (PPARα) modulator pemafibrate improved liver function. PPARα agonists have multiple anti-atherogenic properties. Here, we consider the pathophysiology of MASLD and the mechanisms of action of such drugs and whether such drugs and the combination therapy of such drugs could be the treatments for MASLD.

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 and Muscle-Strengthening Physical Activity, Television Viewing, and Nonalcoholic Fatty Liver Disease: The CARDIA Study

BACKGROUND

The prevalence of non-alcoholic fatty liver disease (NAFLD) in U.S. adults is over 30%, yet the role of lifestyle factors in the etiology of NAFLD remains understudied. We examined the associations of physical activity, by intensity and type, and television viewing with prevalent NAFLD.

METHODS

Cross-sectional analysis of a population-based sample of 2726 Black (49%) and White (51%) adults (Mean (SD) age, 50 (3.6) years; 57.3% female) from the CARDIA study. Exposures were aerobic activity by intensity (moderate, vigorous; hours/week); activity type (aerobic, muscle-strengthening; hours/week); and television viewing (hours/week), examined concurrently in all models and assessed by validated questionnaires. Our outcome was NAFLD (liver attenuation < 51 Hounsfield Units), measured by non-contrast computed tomography, after exclusions for other causes of liver fat. Covariates were sex, age, race, study center, education, diet quality, smoking status, alcohol consumption, and body mass index or waist circumference.

RESULTS

648 participants had NAFLD. In the fully adjusted modified Poisson regression model, the risk ratios per interquartile range of each exposure were moderate-intensity aerobic activity, 1.10 (95% CI, 0.97-1.26); vigorous-intensity aerobic activity, 0.72 (0.63-0.82); muscle-strengthening activity, 0.89 (0.80-1.01); and television viewing, 1.20 (1.10-1.32). Relative to less active participants with higher levels of television viewing, those who participated in ≥2 h/week of both vigorous-intensity aerobic and muscle-strengthening activity and <7 h/week of television viewing had 65% lower risk of NAFLD (risk ratio = 0.35, 95% CI = 0.23-0.51).

CONCLUSION

Adults who follow public health recommendations for vigorous-aerobic and muscle-strengthening activity, as well as minimize television viewing, are considerably less likely to have NAFLD than those who do not follow the recommendations and who have relatively high levels of television viewing.

The effects of exercise training on postprandial glycemia and insulinemia in adults with overweight or obesity and with cardiometabolic disorders: a systematic review and meta-analysis

BACKGROUND

We performed a systematic review and meta-analysis to investigate the effects of exercise training on postprandial glycemia (PPG) and insulinemia (PPI) in adults with overweight or obesity and with cardiometabolic disorders.

METHODS

PubMed, Web of Science, and Scopus databases were searched until May 2022 using the key words "exercise," "postprandial," and "randomized control trial" to identify original studies investigating the effects of exercise training on PPG and/or PPI in adults with a body mass indexes (BMI) ≥ 25 kg.m². Standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated using random effects models to calculate effect sizes for outcomes and to generate forest plots. Sub-group analyses and meta-regressions were performed for potential categorical and continuous moderators.

RESULTS

Twenty-nine studies involving 41 intervention arms and 1,401 participants were included in the systematic review and meta-analysis. Overall, exercise training significantly decreased PPG [-0.36 (95% CI -0.50 to -0.22), p=0.001] and PPI [-0.37 (95% CI -0.52 to -0.21), p=0.001]. Subgroup analyses showed that PPG decreased following both aerobic and resistance training; whereas PPI was reduced following aerobic training, independent of age, BMI, and baseline glucose levels. Meta-regression analyses showed that frequency of exercise sessions, intervention durations, and duration of exercise time, did not moderate the effects of exercise training on PPI or PPG (p>0.05).

CONCLUSION

In adults with overweight or obesity and with cardiometabolic disorders, exercise training is effective for reducing PPG and PPI, across ages and BMIs, irrespective of baseline glucose levels and exercise training characteristics.

Diet and Exercise Exert a Differential Effect on Glucose Metabolism Markers According to the Degree of NAFLD Severity

BACKGROUND

Non-Alcoholic Fatty Liver Disease (NAFLD) and Type 2 Diabetes (T2D) are highly prevalent diseases worldwide. Insulin Resistance (IR) is the common denominator of the two conditions even if the precise timing of onset is unknown. Lifestyle change remains the most effective treatment to manage NAFLD. This study aimed to estimate the effect of the Low Glycemic Index Mediterranean Diet (LGIMD) and exercise (aerobic and resistance) over a one-year period on the longitudinal trajectories of glucose metabolism regulatory pathways.

MATERIALS AND METHODS

In this observational study, 58 subjects (aged 18-65) with different degrees of NAFLD severity were enrolled by the National Institute of Gastroenterology-IRCCS "S. de Bellis", to follow a 12-month program of combined exercise and diet.

RESULTS

The mean age was 55 ± 7 years old. Gender was equally distributed among NAFLD categories. There was a statistically significant main effect of time for glycosylated hemoglobin (Hb1Ac) over the whole period (-5.41, 95% CI: -7.51; -3.32). There was a steady, statistically significant decrease of HbA1c in participants with moderate and severe NAFLD whereas this effect was observed after the 9th month in those with mild NAFLD.

CONCLUSIONS

The proposed program significantly improves glucose metabolism parameters, especially HbA1c.

Vigorous physical activity provides protection against all-cause deaths among adults patients with nonalcoholic fatty liver disease (NAFLD)

BACKGROUND

Mortality benefits of vigorous leisure time physical activity (LTPA) among adults with NAFLD is not known.

AIM

To investigate association between LTPA and reduction in all-cause mortality among adults with NAFLD.

METHODS

We used NHANES (1999-2006) self-reported PA data for adults (≥40 years) with mortality follow-up through December 31, 2015. US-Fatty Liver Index in absence of secondary causes identified NAFLD. Moderate and vigorous LTPA were calculated by the 2018 PA Guidelines for Americans.

RESULTS

NAFLD prevalence among 5211 adults (46.2% male; 75.8% white; mean age 53.2 years) was 32.7%. Adults with NAFLD were less likely to report the recommended minimal PA (≥ 150 min/week, 55.5% vs 64.8%) or highly active PA (≥300 min/week, 39.2% vs 48.5%) compared to adults without NAFLD. Over a median follow-up of 12.3 years, 355 deaths among adults with NAFLD and 510 deaths among adults without NAFLD were registered. In the metabolic comorbidities-adjusted model, adults with NAFLD who reported ≥50% of their total PA as vigorous activity had a 56% reduction in all-cause mortality risk (HR:0.44, 95%CI: 0.25-0.76) and cancer-specific mortality risk (HR: 0.21, 0.06-0.66) but not cardiac-specific mortality (p > 0.05) compared to adults with NAFLD who did not report any LTPA. This association remained significant even among adults with NAFLD who met the recommended minimal PA, among adults with NAFLD who reported any LTPA, and among adults with NAFLD who had metabolic abnormalities and in sensitivity analysis.

CONCLUSIONS

Engaging in vigorous activity is beneficial for adults with NAFLD - especially those with metabolic abnormalities.

Approach to the Patient With Nonalcoholic Fatty Liver Disease

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and type 2 diabetes (T2D), causing substantial burden from hepatic and extrahepatic complications. However, endocrinologists often follow people who are at the highest risk of its more severe form with nonalcoholic steatohepatitis or NASH (i.e., T2D or obesity with cardiometabolic risk factors). Endocrinologists are in a unique position to prevent cirrhosis in this population with early diagnosis and treatment.

OBJECTIVE

This work aims to offer endocrinologists a practical approach for the management of patients with NAFLD, including diagnosis, fibrosis risk stratification, and referral to hepatologists.

PATIENTS

(1) An asymptomatic patient with obesity and cardiometabolic risk factors, found to have hepatic steatosis; (2) a patient with T2D and NASH with clinically significant liver fibrosis; and (3) a liver transplant recipient with a history of NASH cirrhosis, with significant weight regain and with recurrent NAFLD on the transplanted organ.

CONCLUSION

NASH can be reversed with proper management of obesity and of T2D. While no agents are currently approved for the treatment of NASH, treatment should include lifestyle changes and a broader use of structured weight-loss programs, obesity pharmacotherapy, and bariatric surgery. Diabetes medications such as pioglitazone and some glucagon-like peptide 1 receptor agonists may also improve liver histology and cardiometabolic health. Sodium-glucose cotransporter-2 inhibitors and insulin may ameliorate steatosis, but their effect on steatohepatitis remains unclear. Awareness by endocrinologists about, establishing an early diagnosis of fibrosis (ie, FIB-4, liver elastography) in patients at high-risk of cirrhosis, long-term monitoring, and timely referral to the hepatologist are all critical to curve the looming epidemic of cirrhosis from NAFLD.

The effect of 12 weeks of combined training on hepatic fat content and metabolic flexibility of individuals with non-alcoholic fatty liver disease: Protocol of an open-label, single-center randomized control trial

Introduction

Metabolic flexibility (MetF) is the capacity of an organism to oxidate substrate according to substrate availability or demand. The mismatch of substrate availability and oxidation may cause ectopic fat accumulation in the muscle and the liver. The objectives of the study are to examine the effect of 12 weeks of combined exercise on hepatic fat reduction and investigate metabolites related to MetF before and after the high-fat diet between individuals with NAFLD and healthy control with an active lifestyle.

Methods

This study is an open-label, single-center trial randomized controlled clinical study plus a cross-sectional comparison between individuals with NAFLD and healthy control. Individuals with NAFLD were allocated into two groups receiving resistance training (RT) combined with high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT). Anthropometric indicators, clinical blood markers about glucose, lipid metabolism, and hepatic fat content (HFC) were assessed before and after the intervention. The metabolomics was also used to investigate the discrepant metabolites and mechanisms related to MetF.

Discussion

Metabolic flexibility reflects the capacity of an organism to switch the oxidation substrates flexibly, which is associated with ectopic fat accumulation. Our study aimed to explore the discrepant metabolites related to MetF before and after a high-fat diet between individuals with NAFLD and healthy control. In addition, the study also examined the effectiveness of RT combined with HIIT or MICT on hepatic fat reduction and quantificationally analyzed the metabolites related to MetF before and after the intervention. Our results provided a perspective on fatty liver-associated metabolic inactivity.

Trial registration

ClinicalTrials.gov: ChiCTR2200055110; Registered 31 December 2021, http://www.chictr.org.cn/index.aspx.

Cutting edge concepts: Does bilirubin enhance exercise performance?

Exercise performance is dependent on many factors, such as muscular strength and endurance, cardiovascular capacity, liver health, and metabolic flexibility. Recent studies show that plasma levels of bilirubin, which has classically been viewed as a liver dysfunction biomarker, are elevated by exercise training and that elite athletes may have significantly higher levels. Other studies have shown higher plasma bilirubin levels in athletes and active individuals compared to general, sedentary populations. The reason for these adaptions is unclear, but it could be related to bilirubin's antioxidant properties in response to a large number of reactive oxygen species (ROS) that originates from mitochondria during exercise. However, the mechanisms of these are unknown. Current research has re-defined bilirubin as a metabolic hormone that interacts with nuclear receptors to drive gene transcription, which reduces body weight. Bilirubin has been shown to reduce adiposity and improve the cardiovascular system, which might be related to the adaption of bilirubin increasing during exercise. No studies have directly tested if elevating bilirubin levels can influence athletic performance. However, based on the mechanisms proposed in the present review, this seems plausible and an area to consider for future studies. Here, we discuss the importance of bilirubin and exercise and how the combination might improve metabolic health outcomes and possibly athletic performance.

Management of metabolic-associated fatty liver disease: The diabetology perspective

The metabolic syndrome as a consequence of the obesity pandemic resulted in a substantial increase in the prevalence of metabolic-associated fatty live disease (MAFLD) and type 2 diabetes mellitus (T2DM). Because of the similarity in pathobiology shared between T2DM and MAFLD, both disorders coexist in many patients and may potentiate the disease-related outcomes with rapid progression and increased complications of the individual diseases. In fact, awareness about this coexistence and the risk of complications are often overlooked by both hepatologists and diabetologists. Management of these individual disorders in a patient should be addressed wholistically using an appropriate multidisciplinary team approach involving both the specialists and, when necessary, liaising with dieticians and surgeons. This comprehensive review is to compile the current evidence from a diabetologist's perspective on MAFLD and T2DM and to suggest optimal management strategies.

The effect of acute and chronic exercise on hepatic lipid composition

Exercise is recommended for those with, or at risk of nonalcoholic fatty liver disease (NAFLD), owing to beneficial effects on hepatic steatosis and cardiometabolic risk. Whilst exercise training reduces total intrahepatic lipid in people with NAFLD, accumulating evidence indicates that exercise may also modulate hepatic lipid composition. This metabolic influence is important as the profile of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) dramatically affect the metabolic consequences of hepatic lipid accumulation; with SFA being especially lipotoxic. Relatedly, obesity and NAFLD are associated with hepatic PUFA depletion and elevated SFA. This review summarizes the acute (single bout) and chronic (exercise training) effects of exercise on hepatic lipid composition in rodents (acute studies: n = 3, chronic studies: n = 13) and humans (acute studies: n = 1, chronic studies: n = 3). An increased proportion of hepatic PUFA after acute and chronic exercise is the most consistent finding of this review. Mechanistically, this may relate to an enhanced uptake of adipose-derived PUFA (reflecting habitual diet), particularly in rodents. A relative decrease in the proportion of hepatic MUFA after chronic exercise is also documented repeatedly, particularly in rodent models with elevated hepatic MUFA. This outcome is related to decreased hepatic stearoyl-CoA desaturase-1 activity in some studies. Findings regarding hepatic SFA are less consistent and limited by the absence of metabolic challenge in rodent models. These findings require confirmation in well-controlled interventions in people with NAFLD. These studies will be facilitated by recently validated magnetic resonance spectroscopy techniques, able to precisely quantify hepatic lipid composition in vivo.

Effect of alternate day fasting combined with aerobic exercise on non-alcoholic fatty liver disease: A randomized controlled trial

Innovative non-pharmacological lifestyle strategies to treat non-alcoholic fatty liver disease (NAFLD) are critically needed. This study compared the effects of alternate day fasting (ADF) combined with exercise to fasting alone, or exercise alone, on intrahepatic triglyceride (IHTG) content. Adults with obesity and NAFLD (n = 80, 81% female, age: 23-65 years) were randomized to 1 of 4 groups for 3 months: combination of ADF (600 kcal/2,500 kJ "fast day" alternated with an ad libitum intake "feast day") and moderate-intensity aerobic exercise (5 session per week, 60 min/session); ADF alone; exercise alone; or a no-intervention control group. By month 3, IHTG content was significantly reduced in the combination group (-5.48%; 95% CI, -7.77% to -3.18%), compared with the exercise group (-1.30%; 95% CI, -3.80% to 1.20%; p = 0.02) and the control group (-0.17%; 95% CI, -2.17% to 1.83%; p < 0.01) but was not significantly different versus the ADF group (-2.25%; 95% CI, -4.46% to -0.04%; p = 0.05). Body weight, fat mass, waist circumference, and alanine transaminase (ALT) levels significantly decreased, while insulin sensitivity significantly increased in the combination group compared with the control group. Lean mass, aspartate transaminase (AST), HbA1c, blood pressure, plasma lipids, liver fibrosis score, and hepatokines (fetuin-A, FGF-21, and selenoprotein P) did not differ between groups. Combining intermittent fasting with exercise is effective for reducing hepatic steatosis in patients with NAFLD but may offer no additional benefit versus fasting alone.

4. Comprehensive Medical Evaluation and Assessment of Comorbidities: Standards of Care in Diabetes-2023

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Stéatose hépatique non alcoolique : diagnostic et traitement en 2022

La NAFLD (Non Alcoholic Fatty Liver Disease ) est la manifestation hépatique d’un trouble métabolique multisystémique. Elle est la principale cause de maladie hépatique au niveau mondial, avec une prévalence croissante. Bien qu’il s’agisse principalement d’une maladie silencieuse à évolution lente, certains patients présentent un risque élevé de progression de la maladie et d’issues plus graves telles que la cirrhose, le carcinome hépatocellulaire et la transplantation hépatique. Malgré les multiples études menées et les nombreux essais cliniques en cours, il n’existe pas de médicaments approuvés pour la NAFLD/NASH (Non Alcoholic Steato-Hepatitis ), et le traitement doit donc se fonder sur des stratégies de modification du mode de vie. Cette revue explorera la définition et l’épidémiologie courantes de la NAFLD et de la NASH ainsi que les facteurs de risque et les conséquences de la maladie, tout en résumant les recommandations existantes pour le diagnostic, la stratification du risque et la prise en charge de la maladie.

Evolution of the diagnostic value of "the sugar of the blood": hitting the sweet spot to identify alterations in glucose dynamics

In this paper, we provide an overview of the evolution of the definition of hyperglycemia during the past century and the alterations in glucose dynamics that cause fasting and postprandial hyperglycemia. We discuss how extensive mechanistic, physiological research into the factors and pathways that regulate the appearance of glucose in the circulation and its uptake and metabolism by tissues and organs has contributed knowledge that has advanced our understanding of different types of hyperglycemia, namely prediabetes and diabetes and their subtypes (impaired fasting plasma glucose, impaired glucose tolerance, combined impaired fasting plasma glucose, impaired glucose tolerance, type 1 diabetes, type 2 diabetes, gestational diabetes mellitus), their relationships with medical complications, and how to prevent and treat hyperglycemia.

Physical activity is inversely associated with hepatic fibro-inflammation: A population-based cohort study using UK Biobank data

Background & Aims

Physical activity (PA) is recommended in the management of non-alcoholic fatty liver disease (NAFLD) given its beneficial effects on liver fat and cardiometabolic risk. Using data from the UK Biobank population-cohort, this study examined associations between habitual PA and hepatic fibro-inflammation.

Methods

A total of 840 men and women aged 55-70 years were included in this cross-sectional study. Hepatic fibro-inflammation (iron-corrected T1 [cT1]) and liver fat were measured using MRI, whilst body fat was measured using dual-energy X-ray absorptiometry. PA was measured using accelerometry. Generalised linear models examined associations between PA (light [LPA], moderate [MPA], vigorous [VPA], moderate-to-vigorous [MVPA] and mean acceleration) and hepatic cT1. Models were fitted for the whole sample and separately for upper and lower median groups for body and liver fat. Models were adjusted for sociodemographic and lifestyle variables.

Results

In the full sample, LPA (-0.08 ms [-0.12 to -0.03]), MPA, (-0.13 ms [-0.21 to -0.05]), VPA (-1.16 ms [-1.81 to -0.51]), MVPA (-0.14 ms [-0.21 to -0.06]) and mean acceleration (-0.67 ms [-1.05 to-0.28]) were inversely associated with hepatic cT1. With the sample split by median liver or body fat, only VPA was inversely associated with hepatic cT1 in the upper median groups for body (-2.68 ms [-4.24 to -1.13]) and liver fat (-2.33 [-3.73 to -0.93]). PA was unrelated to hepatic cT1 in the lower median groups.

Conclusions

Within a population-based cohort, device-measured PA is inversely associated with hepatic fibro-inflammation. This relationship is strongest with VPA and is greater in people with higher levels of body and liver fat.

Lay summary

This study has shown that people who regularly perform greater amounts of physical activity have a reduced level of inflammation and fibrosis in their liver. This beneficial relationship is particularly strong when more intense physical activity is undertaken (i.e., vigorous-intensity), and is most visible in individuals with higher levels of liver fat and body fat.

Physical activity interventions for glycaemic control in African adults - A systematic review and meta-analysis

BACKGROUND AND AIM

Growing evidence indicates that increasing physical activity may aid in regulating altered glycaemic control, thereby mitigating the risk of diabetes. However, the evidence summarising the efficacy of physical activity on glycaemic control among African adults remains unconsolidated. Our objective was to provide an amalgamated summary of the empirical evidence that explored the effectiveness of physical activity interventions on glycaemic control among African adults.

METHODS

A systematic search of six journal databases for the studies exploring the efficacy of physical activity on glycaemic control among African adults until March 21, 2022, was administered. Two independent reviewers screened the citations based on a priori set eligibility criteria. Data were analysed using inverse variance method and a summary of findings was synthesised using the Grading of Recommendations, Assessment, Development and Evaluations approach.

RESULTS

Of the 14,624 citations retrieved, 26 articles with 1474 participants were included for final analysis. Most of the included trials had a high risk of bias (N = 20; 76.92%). Our review found a significant reduction in fasting blood glucose (FBG, -2.18 [ 95% CI -3.18, -1.18] mmol/L), insulin (-0.99 [-2.71, 0.74] μU/L), Glycosylated haemoglobin (HbA1C) (-0.53% [-0.88, -0.19]), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (-0.74% [-1.10, -0.38]) and insulin sensitivity (-0.90 μU/l/min [-1.75, -0.06]) following physical activity interventions. The review reports low certainty of evidence across all outcome measures.

DISCUSSION AND CONCLUSION

Physical activity interventions were found to improve glycaemic control among African adults. However, the optimal physical activity dose for demonstrating meaningful benefits on glucose tolerance still remains unclear due to the limited number of primary studies available.

Race and Ethnicity in Non-Alcoholic Fatty Liver Disease (NAFLD): A Narrative Review

Non-alcoholic fatty liver disease (NAFLD) is a significant public health concern worldwide with a complex etiology attributed to behavioural, environmental, and genetic causes. The worldwide prevalence of NAFLD is estimated to be 32.4% and constantly rising. Global data, however, indicate considerable heterogeneity among studies for both NAFLD prevalence and incidence. Identifying variables that affect the estimated epidemiological measures is essential to all stakeholders, including patients, researchers, healthcare providers, and policymakers. Besides helping with the research on disease etiology, it helps to identify individuals at risk of the disease, which in turn will outline the focus of the preventive measures and help to fittingly tailor individualized treatments, targeted prevention, screening, or treatment programs. Several studies suggest differences in the prevalence and severity of NAFLD by race or ethnicity, which may be linked to differences in lifestyle, diet, metabolic comorbidity profile, and genetic background, among others. Race/ethnicity research is essential as it can provide valuable information regarding biological and genetic differences among people with similar cultural, dietary, and geographical backgrounds. In this review, we examined the existing literature on race/ethnicity differences in susceptibility to NAFLD and discussed the contributing variables to such differences, including diet and physical activity, the comorbidity profile, and genetic susceptibility. We also reviewed the limitations of race/ethnicity studies in NAFLD.

Maternal Low-Protein Diet during Puberty and Adulthood Aggravates Lipid Metabolism of Their Offspring Fed a High-Fat Diet in Mice

A maternal low-protein (LP) diet during gestation and/or lactation results in metabolic syndrome in their offspring. Here, we investigated the effect of maternal LP diet during puberty and adulthood on the metabolic homeostasis of glucose and lipids in offspring. Female mice were fed with normal-protein (NP) diet or a LP diet for 11 weeks. Male offspring were then fed with a high-fat diet (NP-HFD and LP-HFD groups) or standard chow diet (NP-Chow and LP-Chow groups) for 4 months. Results showed that maternal LP diet during puberty and adulthood did not alter the insulin sensitivity and hepatic lipid homeostasis of their offspring under chow diet, but aggravated insulin resistance, hepatic steatosis, and hypercholesterolemia of offspring in response to a post-weaning HFD. Accordingly, transcriptomics study with offspring’s liver indicated that several genes related to glucose and lipid metabolism, including lipoprotein lipase (Lpl), long-chain acyl-CoA synthetase 1 (Acsl1), Apoprotein A1 (Apoa1), major urinary protein 19 (Mup19), cholesterol 7α hydroxylase (Cyp7a1) and fibroblast growth factor 1 (Fgf1), were changed by maternal LP diet. Taken together, maternal LP diet during puberty and adulthood could disarrange the expression of metabolic genes in the liver of offspring and aggravate insulin resistance and hepatic steatosis in offspring fed a HFD.

FOXO1 is downregulated in obese mice subjected to short-term strength training

Obesity is a worldwide health problem and is directly associated with insulin resistance and type 2 diabetes. The liver is an important organ for the control of healthy glycemic levels, since insulin resistance in this organ reduces phosphorylation of forkhead box protein 1 (FOXO1) protein, leading to higher hepatic glucose production (HGP) and fasting hyperglycemia. Aerobic physical training is known as an important strategy in increasing the insulin action in the liver by increasing FOXO1 phosphorylation and reducing gluconeogenesis. However, little is known about the effects of strength training in this context. This study aimed to investigate the effects of short-term strength training on hepatic insulin sensitivity and glycogen synthase kinase-3β (GSK3β) and FOXO1 phosphorylation in obese (OB) mice. To achieve this goal, OB Swiss mice performed the strength training protocol (one daily session for 15 days). Short-term strength training increased the phosphorylation of protein kinase B and GSK3β in the liver after insulin stimulus and improved the control of HGP during the pyruvate tolerance test. On the other hand, sedentary OB animals reduced FOXO1 phosphorylation and increased the levels of nuclear FOXO1 in the liver, increasing the phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) content. The bioinformatics analysis also showed positive correlations between hepatic FOXO1 levels and gluconeogenic genes, reinforcing our findings. However, strength-trained animals reverted to this scenario, regardless of body adiposity changes. In conclusion, short-term strength training is an efficient strategy to enhance the insulin action in the liver of OB mice, contributing to glycemic control by reducing the activity of hepatic FOXO1 and lowering PEPCK and G6Pase contents.

The Effect of Low Glycemic Index Mediterranean Diet and Combined Exercise Program on Metabolic-Associated Fatty Liver Disease: A Joint Modeling Approach

Background: Excessive caloric intake and reduced energy expenditure are associated with the onset of metabolic-associated fatty liver disease (MAFLD). The aim of this study was to probe the benefits of a low glycemic index Mediterranean diet (LGIMD) and a combined exercise program (CEP) on MAFLD by monitoring the clinical process through anthropometric measurement, body mass index (BMI), and specific biomarkers, such as the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Methods: The study was conducted at the National Institute of Gastroenterology, ‘S. de Bellis’, Italy. Subjects were invited to join the study for 12 months. Results: 54 participants were enrolled. Joint modeling of longitudinal and time-to-event data was applied. Overall, a statistically significant direct effect of LGIMD/CEP adherence on ln (BMI), a statistically significant direct effect of LGIMD/CEP adherence on time-to-event and a strong statistically significant direct effect of log (BMI) on time-to-event were observed. In addition, a statistically significant direct effect of LGIMD/CEP adherence on ln(HOMA-IR), a statistically significant direct effect of LGIMD/CEP adherence on time-to-event and a statistically significant direct effect of ln(HOMA-IR) on time-to-event were observed. Conclusions: LGIMD/CEP significantly improved MAFLD status; in addition, longitudinal BMI and HOMA-IR were good predictors of the disappearance of diagnostic criteria for MAFLD.

The effect of exercise training on adipose tissue insulin sensitivity: A systematic review and meta-analysis

This systematic review and meta-analysis determined the impact of exercise training on adipose tissue insulin sensitivity in adults. Its scope extended to studies measuring whole-body and localized subcutaneous adipose tissue insulin sensitivity using validated techniques. Consensus from four studies demonstrates that exercise training improved whole-body adipose tissue insulin sensitivity when measured via stable-isotope lipid tracers (rate of appearance suppression in response to hyperinsulinemia). Meta-analysis of 20 studies (26 intervention arms) employing the adipose tissue insulin resistance index (ADIPO-IR) supported these findings (-10.63 [-14.12 to -7.15] pmol·L^-1  × mmol·L^-1 ). With ADIPO-IR, this response was greater in studies documenting weight loss and shorter sampling time (≤48 h) post-training. Overall, exercise training did not affect whole-body adipose tissue insulin sensitivity in seven studies (11 intervention arms) measuring the suppression of circulating non-esterified fatty acids in response to insulin infusion (1.51 [-0.12 to 3.14]%); however, subgroup analysis identified an enhanced suppression post-training in trials reporting weight loss. From four microdialysis studies, consensus indicates no effect of exercise training on localized (abdominal/femoral) adipose tissue insulin sensitivity, potentially suggesting that enhanced whole-body responses are related to improvements in central adipose depots. However, heterogeneity within microdialysis protocols dictates that findings must be viewed with caution.

NASHFit: A randomized controlled trial of an exercise training program to reduce clotting risk in patients with NASH

BACKGROUND AND AIMS

NASH is a common disease associated with increased rates of thromboembolism (TE). Although exercise training can lessen thrombotic risk in patients with vascular disease, whether similar findings are observed in patients with NASH is open for study.

APPROACH AND RESULTS

We conducted a 20-week randomized controlled clinical trial involving patients with biopsy-confirmed NASH. Patients were randomly assigned (2:1 ratio) to receive either an exercise training program or standard clinical care. The primary endpoint was change in plasminogen activator inhibitor 1 (PAI-1) level, an established thrombotic biomarker. Twenty-eight patients were randomly assigned (18 exercise training and 10 standard clinical care). PAI-1 level was significantly decreased by exercise training when compared to standard clinical care (-40 ± 100 vs. +70 ± 63 ng/ml; p = 0.02). Exercise training decreased MRI proton density fat fraction (MRI-PDFF; -4.7 ± 5.6 vs. 1.2 ± 2.8% absolute liver fat; p = 0.01); 40% of exercise subjects had a ≥30% relative reduction in MRI-PDFF (histological response threshold) compared to 13% for standard of care (p < 0.01). Exercise training improved fitness (VO₂ peak, +3.0 ± 5.6 vs. -1.8 ± 5.1 ml/kg/min; p = 0.05) in comparison to standard clinical care.

CONCLUSIONS

This clinical trial showed that, independent of weight loss or dietary change, exercise training resulted in a significantly greater decrease in thrombotic risk than standard clinical care in patients with NASH, in parallel with MRI-PDFF reduction and improvement in fitness. Future studies are required to determine whether exercise training can directly impact patient outcomes and lower rates of TE.

Effect of Exercise Training on Serum Transaminases in Patients With Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

Background/Purpose: Nonalcoholic fatty liver disease (NAFLD) constitutes a spectrum of liver diseases associated with various metabolic disorders. Exercise interventions reportedly manage the clinical outcomes of NAFLD, but their efficacy depends on exercise as well as characteristics of patient. We hypothesized that exercise could alleviate the elevated transaminases level, which may be associated with the characteristics of patients (age/bodyweight/sex) or exercise variables (frequency/intensity/duration). Therefore, we examined the effect of exercise on serum transaminases, and identified the variables influencing transaminases in NAFLD patients.

Methods: Article search was conducted using electronic databases (PubMed, Web of Science, EMBASE, ScienceDirect, Google Scholar) until December 2021. Studies that involved examination and comparison of the effect of an exercise intervention on alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in NAFLD/nonalcoholic steatohepatitis patients were included. We calculated pooled effect upon a meta-analysis, determined correlations (between transaminases and characteristics of patients/exercise) by meta-regression, and assessed the influencing variable through subgroup analysis.

Results: A total of 18 studies (22 trials) with 1098 NAFLD patients (exercise = 568; control = 530) were included. The pooled outcomes revealed that exercise intervention significantly decreased both ALT (p = 0.004) and AST (p = 0.001) levels in NAFLD patients. Meta-regression analysis showed decreased ALT (coef. = 1.138, p &lt; 0.01) and AST (coef. = 0.459, p = 0.041) after intervention was correlated with the age of patients. Particularly, patients aged 30–39 years (MD: −25.89 U/L, 95% CI: −36.40 to −15.37, p &lt; 0.00001) and 40–49 years (MD: −12.17 U/L, 95% CI: −20.38 to −3.96, p = 0.004) represented a substantial decrease in ALT levels. Additionally, the 50–59 years age group tended to have decreased ALT levels (MD: −3.94 U/L, 95% CI: −8.19 to 0.31, p = 0.07); however, patients above 60 years did not respond (p = 0.92) to exercise intervention. In contrast, exercise-induced AST reduction was found in only the 30–39 years age group (MD: −11.92 U/L, 95% CI: −16.78 to −7.06, p &lt; 0.00001) and not in patients under the 40–49 (p = 0.19), and 50–59 groups (p = 0.12) and above 60 years (p = 0.15).

Conclusion: Our findings suggest that the age of NAFLD patients may be an important variable in improving the levels of serum transaminases, and clinically young patients may have greater benefits from exercise than older patients.

Efficacy of aerobic and resistance exercises in improving visceral adipose in patients with non-alcoholic fatty liver: a meta-analysis of randomized controlled trials

Background Non-alcoholic fatty liver disease (NAFLD) is a common chronic disease that can cause liver deterioration if insufficiently diagnosed and untreated. The verification of whether exercise interventions improve liver enzymes and lipid and glucose parameters is scant.

Aim We conducted this systematic review and meta-analysis to examine the efficacy of aerobic and resistance exercise interventions in patients with NAFLD.

Methods We searched the related studies in the PubMed, Embase, Cochrane Library, and Web of Science databases. We screened 1129 articles published before September 1, 2021, based on the inclusion and exclusion standards, after which 17 articles with a total of 1168 participants were finally included. The indices of liver enzymes and lipid and glucose metabolism were gathered and examined by Stata SE.

Results The outcomes suggested that aerobic and resistance exercise can markedly improve the parameters of liver enzymes, blood lipids, and glucose, and especially visceral adipose tissue (weighted mean different [WMD] = −8.3 at 95% CI [−11.59 to −5.00], p < 0.0001), in patients with NAFLD.

Conclusion This study demonstrated that aerobic and resistance exercises positively affect NAFLD treatment. To further quantify the effects on patients with NAFLD, a more specific and uniform exercise program should be proposed.

American Association of Clinical Endocrinology Clinical Practice Guideline for the Diagnosis and Management of Nonalcoholic Fatty Liver Disease in Primary Care and Endocrinology Clinical Settings: Co-Sponsored by the American Association for the Study of Liver Diseases (AASLD)

OBJECTIVE

To provide evidence-based recommendations regarding the diagnosis and management of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) to endocrinologists, primary care clinicians, health care professionals, and other stakeholders.

METHODS

The American Association of Clinical Endocrinology conducted literature searches for relevant articles published from January 1, 2010, to November 15, 2021. A task force of medical experts developed evidence-based guideline recommendations based on a review of clinical evidence, expertise, and informal consensus, according to established American Association of Clinical Endocrinology protocol for guideline development.

RECOMMENDATION SUMMARY

This guideline includes 34 evidence-based clinical practice recommendations for the diagnosis and management of persons with NAFLD and/or NASH and contains 385 citations that inform the evidence base.

CONCLUSION

NAFLD is a major public health problem that will only worsen in the future, as it is closely linked to the epidemics of obesity and type 2 diabetes mellitus. Given this link, endocrinologists and primary care physicians are in an ideal position to identify persons at risk on to prevent the development of cirrhosis and comorbidities. While no U.S. Food and Drug Administration-approved medications to treat NAFLD are currently available, management can include lifestyle changes that promote an energy deficit leading to weight loss; consideration of weight loss medications, particularly glucagon-like peptide-1 receptor agonists; and bariatric surgery, for persons who have obesity, as well as some diabetes medications, such as pioglitazone and glucagon-like peptide-1 receptor agonists, for those with type 2 diabetes mellitus and NASH. Management should also promote cardiometabolic health and reduce the increased cardiovascular risk associated with this complex disease.

Effect of a Six-Month Lifestyle Intervention on the Physical Activity and Fitness Status of Adults with NAFLD and Metabolic Syndrome

(1) Background: Physical inactivity has been linked to NAFLD, and exercise has been reported as useful to reduce intrahepatic fat content in NAFLD. (2) Objectives: To assess the physical activity (PA) and fitness status after a six-month lifestyle intervention (diet and PA) in adults with NAFLD and metabolic syndrome (MetS). (3) Design: Prospective cohort analysis of data obtained between baseline and six-year parallel-group randomized trial (n = 155, aged 40-60 years old, with MetS and NAFLD). Participants were randomized into three nutritional and PA intervention groups: Conventional diet (CD); MedDiet-high meal frequency (MD-HMF); MedDiet-physical activity (MD-PA). (4) Methods: PA and fitness status were assessed using a validated Minnesota questionnaire, ALPHA-FIT test battery, accelerometers, and functional fitness score. Information related to age, gender, education level, marital status, socioeconomic status, smoking habit, and alcohol consumption were also obtained. (5) Results: The CD group had higher improvement in standing handgrip than the MD-HMF group. The MD-PA group did more modified push-up repetitions than the CD group. The MD-PA and CD groups showed higher sitting handgrip than the MD-HMF group. The MD-HMF group showed the highest decrease in aerobic capacity. The MD-PA group showed lower light intensity PA/day than the CD and MD-HMF groups. The MD-PA group showed higher moderate intensity PA than the CD and MD-HMF groups. The CD group reported more METs per day than the MD-HMF group. (6) Conclusions: Lifestyle six-month intervention with diet and regular PA improved functional fitness in middle-aged patients with NAFLD and MetS. Aerobic capacity improved in patients who followed a Mediterranean diet and regular training sessions at six months.

A Low Glycemic Index Mediterranean Diet Combined with Aerobic Physical Activity Rearranges the Gut Microbiota Signature in NAFLD Patients

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, and its prevalence worldwide is increasing. Several studies support the pathophysiological role of the gut–liver axis, where specific signal pathways are finely tuned by intestinal microbiota both in the onset and progression of NAFLD. In the present study, we investigate the impact of different lifestyle interventions on the gut microbiota composition in 109 NAFLD patients randomly allocated to six lifestyle intervention groups: Low Glycemic Index Mediterranean Diet (LGIMD), aerobic activity program (ATFIS_1), combined activity program (ATFIS_2), LGIMD plus ATFIS_1 or ATFIS2 and Control Diet based on CREA-AN (INRAN). The relative abundances of microbial taxa at all taxonomic levels were explored in all the intervention groups and used to cluster samples based on a statistical approach, relying both on the discriminant analysis of principal components (DAPCs) and on a linear regression model. Our analyses reveal important differences when physical activity and the Mediterranean diet are merged as treatment and allow us to identify the most statistically significant taxa linked with liver protection. These findings agree with the decreased ‘controlled attenuation parameter’ (CAP) detected in the LGIMD-ATFIS_1 group, measured using FibroScan^®. In conclusion, our study demonstrates the synergistic effect of lifestyle interventions (diet and/or physical activity programs) on the gut microbiota composition in NAFLD patients.

The impact of high-intensity interval training on postprandial glucose and insulin: A systematic review and meta-analysis

AIMS

We performed a systematic review and meta-analysis to investigate the effects of high-intensity interval training (HIIT) on postprandial glucose (PPG) and insulin (PPI) versus non-exercise control and moderate-intensity continuous training (MICT) in participants with both normal and impaired glucose.

METHODS

The PubMed, Scopus, and Web of Science electronic databases were searched up to October 2021 for randomized trials evaluating HIIT versus control and/or versus MICT on glucose and insulin AUC using oral glucose tolerance testing. Subgroup analyses based on intervention duration (short-duration < 8 weeks, moderate-duration ≥ 8 weeks), baseline glucose levels (normal glucose and impaired glucose) and type of HIIT (L-HIIT and SIT) were also conducted across included studies.

RESULTS

A total of 25 studies involving 870 participants were included in the current meta-analysis. HIIT effectively reduced glucose [-0.37 (95% CI -0.60 to -0.13), p = 0.002] and insulin [-0.36 (95% CI -0.68 to -0.04), p = 0.02] AUC when compared with a CON group. Reductions in glucose AUC were significant for those with impaired glucose at baseline (p = 0.03), but not for those with normal glucose levels (p = 0.11) and following moderate-duration (p = 0.01), but not short-duration interventions (p = 0.18). However, there were no differences in glucose (p = 0.76) or insulin (p = 0.43) AUC between HIIT and MICT intervention arms.

CONCLUSIONS

Our results demonstrated that both HIIT and MICT are effective for reducing postprandial glycemia and insulinemia, particularly by moderate-duration interventions, and in those with impaired glucose.

The Effect of High-intensity Interval Training vs Moderate-intensity Continuous Training on Liver Fat: A Systematic Review and Meta-Analysis

CONTEXT

Non-alcoholic fatty liver disease, characterized by excess fat accumulation in the liver, is considered the hepatic manifestation of metabolic syndrome. Recent findings have shown that high-intensity interval training (HIIT) can reduce liver fat but it is unclear whether this form of exercise is superior to traditional moderate-intensity continuous training (MICT).

OBJECTIVE

The aim of this systematic review was to determine the effect of HIIT vs MICT on liver fat in adults. A secondary aim was to investigate the interaction between total weekly exercise volume and exercise-related energy expenditure and change in liver fat.

METHODS

Relevant databases were searched up to December 2020 for randomized trials, comparing HIIT to control, MICT to control, or HIIT to MICT. Studies were excluded if they did not implement 2 or more weeks' intervention or assess liver fat using magnetic resonance-based techniques. Weighted mean differences and 95% CIs were calculated. Regression analyses were undertaken to determine the interaction between weekly exercise volume in minutes and kilocalories (kcal) with change in liver fat content.

RESULTS

Of the 28 268 studies screened, 19 were included involving 745 participants. HIIT and MICT both elicited moderate reductions in liver fat content when compared to control (HIIT: -2.85%, 95% CI, -4.86 to -0.84, P = .005, I2 = 0%, n = 114, low-certainty evidence; MICT: -3.14%, 95% CI, -4.45 to -1.82, P < .001, I2 = 5.2%, n = 533, moderate-certainty evidence). There was no difference between HIIT and MICT (-0.34%, 95% CI, -2.20 to 1.52, P = .721, I2 = 0%, n = 177, moderate-certainty evidence). Neither total exercise volume in minutes (β = .0002, SE = 0.0017, Z = 0.13, P = .89) nor exercise-related energy expenditure in kcal (β = .0003, SE = 0.0002, Z = 1.21, P = .23) were related to changes in liver fat content.

CONCLUSION

HIIT elicits comparable improvements in liver fat to MICT despite often requiring less energy and time commitment. Further studies should be undertaken to assess the relative importance of aerobic exercise prescription variables, such as intensity, on liver fat.

Reactive Oxygen Species (ROS) and Antioxidants as Immunomodulators in Exercise: Implications for Heme Oxygenase and Bilirubin

Exercise is commonly prescribed as a lifestyle treatment for chronic metabolic diseases as it functions as an insulin sensitizer, cardio-protectant, and essential lifestyle tool for effective weight maintenance. Exercise boosts the production of reactive oxygen species (ROS) and subsequent transient oxidative damage, which also upregulates counterbalancing endogenous antioxidants to protect from ROS-induced damage and inflammation. Exercise elevates heme oxygenase-1 (HO-1) and biliverdin reductase A (BVRA) expression as built-in protective mechanisms, which produce the most potent antioxidant, bilirubin. Together, these mitigate inflammation and adiposity. Moderately raising plasma bilirubin protects in two ways: (1) via its antioxidant capacity to reduce ROS and inflammation, and (2) its newly defined function as a hormone that activates the nuclear receptor transcription factor PPARα. It is now understood that increasing plasma bilirubin can also drive metabolic adaptions, which improve deleterious outcomes of weight gain and obesity, such as inflammation, type II diabetes, and cardiovascular diseases. The main objective of this review is to describe the function of bilirubin as an antioxidant and metabolic hormone and how the HO-1-BVRA-bilirubin-PPARα axis influences inflammation, metabolic function and interacts with exercise to improve outcomes of weight management.

Does aerobic exercise reduce NASH and liver fibrosis in patients with non-alcoholic fatty liver disease? A systematic literature review and meta-analysis

BACKGROUND

Exercise is an effective strategy for the prevention and regression of hepatic steatosis in patients with non-alcoholic fatty liver disease (NAFLD), but it is unclear whether it can reduce advanced stages of NAFLD, i.e., steatohepatitis and liver fibrosis. Furthermore, it is not evident which modality of exercise is optimal to improve/attenuate NAFLD.

OBJECTIVES

The aim is to systematically review evidence for the effect of aerobic exercise (AE) on NAFLD, in particular non-alcoholic steatohepatitis (NASH) and liver fibrosis.

METHODS

A systematic literature search was conducted in Medline and Embase. Studies were screened and included according to predefined criteria, data were extracted, and the quality was assessed by Cochrane risk of bias tools by two researchers independently according to the protocol registered in the PROSPERO database (CRD42021270059). Meta-analyses were performed using a bivariate random-effects model when there were at least three randomized intervention studies (RCTs) with similar intervention modalities and outcome.

RESULTS

The systematic review process resulted in an inclusion a total of 24 studies, 18 RCTs and six non-RCTs, encompassing 1014 patients with NAFLD diagnosed by histological or radiological findings. Studies were grouped based on the type of AE: moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). A total of twelve meta-analyses were conducted. Compared to controls, MICT resulted in a mean difference (MD) in the NAFLD biomarkers alanine transaminase (ALT) and aspartate aminotransferase (AST) of -3.59 (CI: -5.60, -1.59, p<0.001) and -4.05 (CI: -6.39, -1.71, p<0.001), respectively. HIIT resulted in a MD of -4.31 (95% CI: -9.03, 0.41, p=0.07) and 1.02 (95% CI: -6.91, 8.94, p=0.8) for ALT and AST, respectively. Moreover, both AE types compared to controls showed a significantly lower magnetic resonance spectroscopy (MRS) determined liver fat with a MD of -5.19 (95% CI: -7.33, -3.04, p<0.001) and -3.41 (95% CI: -4.74, -2.08, p<0.001), for MICT and HIIT respectively. MICT compared to controls resulted in a significantly higher cardiorespiratory fitness (MD: 4.43, 95% CI: 0.31, 8.55, p=0.03).

CONCLUSION

Liver fat is decreased by AE with a concomitant decrease of liver enzymes. AE improved cardiorespiratory fitness. Further studies are needed to elucidate the impact of different types of AE on hepatic inflammation and fibrosis.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier (CRD42021270059).

The Role of Physical Activity in Nonalcoholic and Metabolic Dysfunction Associated Fatty Liver Disease

Sedentary behavior constitutes a pandemic health threat contributing to the pathophysiology of obesity and type 2 diabetes (T2D). Sedentarism is further associated with liver disease and particularly with nonalcoholic/metabolic dysfunction associated fatty liver disease (NAFLD/MAFLD). Insulin resistance (IR) represents an early pathophysiologic key element of NAFLD/MAFLD, prediabetes and T2D. Current treatment guidelines recommend regular physical activity. There is evidence, that physical exercise has impact on a variety of molecular pathways, such as AMP-activated protein kinase and insulin signaling as well as glucose transporter 4 translocation, modulating insulin action, cellular substrate flow and in particular ectopic lipid and glycogen storage in a positive manner. Therefore, physical exercise can lead to substantial clinical benefit in persons with diabetes and/or NAFLD/MAFLD. However, experience from long term observational studies shows that the patients’ motivation to exercise regularly appears to be a major limitation. Strategies to integrate everyday physical activity (i.e., nonexercise activity thermogenesis) in lifestyle treatment schedules might be a promising approach. This review aggregates evidence on the impact of regular physical activity on selected molecular mechanisms as well as clinical outcomes of patients suffering from IR and NAFLD/MAFLD.

Short-term combined training reduces hepatic steatosis and improves hepatic insulin signaling

Hepatic steatosis is directly associated with hepatic inflammation and insulin resistance, which is correlated with hyperglycemia and type 2 diabetes mellitus (T2DM). Aerobic and strength training have been pointed out as efficient strategies against hepatic steatosis. However, little is known about the effects of the combination of those two protocols on hepatic steatosis. Therefore, this study aimed to evaluate the impact of short-term combined training (STCT) on glucose homeostasis and in the synthesis and oxidation of fat in the liver of obesity-induced mice with hepatic steatosis. Swiss mice were distributed into three groups: control lean (CTL), sedentary obese (OB), and combined training obese (CTO). The CTO group performed the STCT protocol, which consisted of strength and aerobic exercises in the same session. The protocol lasted seven days. The CTO group reduced the glucose levels and fatty liver when compared to the OB group. Interestingly, these results were observed even without reductions in body adiposity. CTO group also showed increased hepatic insulin sensitivity, with lower hepatic glucose production (HGP). STCT reduced the expression of the lipogenic genes Fasn and Scd1 and hepatic inflammation, as well as increased the ACC phosphorylation and the oxidative genes Cpt1a and Ppara, reverting the complications caused by obesity. Since this protocol increased lipid oxidation and reduced hepatic lipogenesis, regardless of body fat mass decrease, it can be considered an effective non-pharmacological strategy for the treatment of hepatic steatosis.

Exercise Training Protocols to Improve Obesity, Glucose Homeostasis, and Subclinical Inflammation

The global pandemics of obesity and sedentarism are associated with poor quality of life and increased risks for development of inflammatory chronic diseases, including type 2 diabetes, cardiovascular diseases, and cancer. Physical activity is considered as an antidote to counteract the development of chronic sterile inflammatory diseases. Thus, we review the most promising exercise training protocols for promoting weight loss, improving glucose homeostasis, and reducing inflammation. We discuss the advantages and disadvantages of moderate-intensity continuous aerobic training, high-intensity aerobic training, and combined (aerobic + resistance) training. Our aim with this chapter is to provide evidence and guidance for choosing the most appropriate protocols of exercise training according to the goals of the patient.

Current management of NAFLD/NASH

NAFLD is the most common cause of liver disease worldwide, and its prevalence is significantly increasing. Studies have shown that it is associated with comorbidities such as diabetes, metabolic syndrome and obesity. Early diagnosis and management are highly important and could modify the prognosis of the disease. Evaluating the possibility of multiple aetiologies and recognizing the additional causes of liver disease should be a part of the patient's initial assessment. There are no approved drug treatments as yet, so the main management strategies should involve lifestyle changes such as physical activity and dietary re-education.

Mitochondria-Associated Membranes (MAMs): A Novel Therapeutic Target for Treating Metabolic Syndrome

Mitochondria-associated Endoplasmic Reticulum (ER) Membranes (MAMs) are the cellular structures that connect the ER and mitochondria and mediate communication between these two organelles. MAMs have been demonstrated to be involved in calcium signaling, lipid transfer, mitochondrial dynamic change, mitophagy, and the ER stress response. In addition, MAMs are critical for metabolic regulation, and their dysfunction has been reported to be associated with metabolic syndrome, including the downregulation of insulin signaling and the accelerated progression of hyperlipidemia, obesity, and hypertension. This review covers the roles of MAMs in regulating insulin sensitivity and the molecular mechanism underlying MAM-regulated cellular metabolism and reveals the potential of MAMs as a therapeutic target in treating metabolic syndrome.

The association between cardiorespiratory fitness, liver fat and insulin resistance in adults with or without type 2 diabetes: a cross-sectional analysis

Background

Exercise-induced improvements in cardiorespiratory fitness (CRF) often coincide with improvements in insulin sensitivity and reductions in liver fat content. However, there are limited data concerning the relationship between CRF and liver fat content in adults with varying degrees of metabolic dysfunction.

Methods

The aim of this study was to examine the association between CRF, liver fat content, and insulin resistance in inactive adults with obesity and with or without type 2 diabetes (T2D), via cross-sectional analysis. CRF was determined via a graded exercise test. Liver fat content was assessed via proton magnetic resonance spectroscopy and insulin resistance was assessed via homeostatic model of insulin resistance (HOMA-IR). A partial correlation analysis, controlling for age and gender, was performed to determine the association between CRF, demographic, cardiometabolic, and anthropometric variables. Independent t tests were performed to compare cardiometabolic outcomes between participants with T2D and participants without T2D.

Results

Seventy-two adults (46% male) with a mean age of 49.28 ± 10.8 years, BMI of 34.69 ± 4.87 kg/m², liver fat content of 8.37 ± 6.90%, HOMA-IR of 3.07 ± 2.33 and CRF of 21.52 ± 3.77 mL/kg/min participated in this study. CRF was inversely associated with liver fat content (r = − 0.28, p = 0.019) and HOMA-IR (r = − 0.40, p < 0.001). Participants with T2D had significantly higher liver fat content (+ 3.66%, p = 0.024) and HOMA-IR (+ 2.44, p < 0.001) than participants without T2D. Participants with T2D tended to have lower CRF than participants without T2D (− 1.5 ml/kg/min, p = 0.094).

Conclusion

CRF was inversely associated with liver fat content and insulin resistance. Participants with T2D had lower CRF than those without T2D, however, the difference was not statistically significant. Further longitudinal studies are required to elucidate the relationship between CRF and the progression of obesity-related diseases such as T2D.

Registration: ACTRN12614001220651 (retrospectively registered on the 19th November 2014) and ACTRN12614000723684 (prospectively registered on the 8th July 2014).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-021-00261-9.

Evidence-Based Aerobic Exercise Training in Metabolic-Associated Fatty Liver Disease: Systematic Review with Meta-Analysis

Background: This meta-analysis evaluates the overall effect of the non-pharmacological intervention, aerobic exercise, upon serum liver enzymes levels, glucose metabolism and anthropometric measures amongst patients with metabolic associated fatty liver disease (MAFLD). It also examines whether the effects on these outcomes are moderated by the aerobic training protocol when considered according to the American College of Sports Medicine (ACSM) recommended FITT (frequency, intensity, time, type) principles. Approach and Results: Fifteen randomized control trials were included in the meta-analysis. Compared with usual care, continuous and interval training showed significant efficacy in alanine aminotransferase (ALT) level improvement (MD = −2.4, 95% CI: −4.34 to −0.46 p = 0.015, I² = 9.1%). Interventions based on all types of aerobic exercise protocols showed significant improvement of intrahepatic triglycerides (MD = −4.0557, 95% CI: −5.3711 to −2.7403, p < 0.0001, I² = 0%) and BMI (MD = −0.9774, 95% CI: −1.4086 to −0.5462, p < 0.0001, I² = 0). Meta-regression analysis demonstrated a significant correlation between total intervention time and ALT level (for all aerobic protocols: 6.0056, se = 2.6896, z = 2.2329, p = 0.02; as well as for continuous and interval aerobic protocols: 5.5069, se = 2.7315, z = 2.016, p = 0.04). Conclusions: All types of aerobic exercise protocols are effective at improving intrahepatic triglycerides and lead to a reduction in body mass index. In addition, continuous and interval aerobic exercise may be more effective at improving ALT ≤12 weeks intervention time benefits the management of MAFLD.

The impact of high intensity interval training on liver fat content in overweight or obese adults: A meta-analysis

Liver fat is a marker of the metabolic derangements associated with obesity for which exercise training is a potential therapy. We therefore performed a systematic meta-analysis to investigate the effect of high intensity interval training (HIIT) on liver fat content in overweight or obese adults with metabolic disorders. PubMed, Scopus, Web of Science and the Cochrane were searched up to October 2020 for HIIT vs. Control (CON) or HIIT vs. moderate intensity interval training (MICT) studies on liver fat content in overweight and obese individuals with metabolic disorders. Standardized mean differences (SMD) and 95% confidence intervals (95% CIs) were calculated. Ten studies involving 333 participants were included in the meta-analysis. Based on studies that directly compared HIIT and CON (6 studies), HIIT was beneficial for promoting a reduction in liver fat [-0.51 (95% CI: -0.85 to -0.17), p = 0.003]. However, there were no significant evidence for an effect of HIIT on liver fat [-0.07 (95% CI: -0.33 to 0.19), p = 0.59], when compared with MICT (7 studies). These results suggest that a HIIT could induce improvements in liver fat of overweight and obese adults with metabolic disorders despite no weight loss.