Presence of sarcopenia identifies a special group of lean NAFLD in middle-aged and older people

Beyond obesity: lean metabolic dysfunction-associated steatohepatitis from unveiling molecular pathogenesis to therapeutic advancement

Nonalcoholic fatty liver disease (NAFLD), now known by the name of metabolic dysfunction-associated fatty liver disease (MAFLD), with increased global incidence, has been recognized as a significant metabolic disorder. NAFLD includes a spectrum liver disease from hepatocellular fat accumulation (isolated steatosis) to an advanced form of liver injury known as nonalcoholic steatohepatitis (NASH), which refers to distinct histologic features, including hepatocellular steatosis and injury, necroinflammation, and eventually fibrosis. Nonobese or lean individuals associated with metabolic dysregulation usually demonstrated diverse risk factors compared to obese MAFLD. The presence of normal range body mass index (BMI) and excess visceral adiposity with increased cardiometabolic and renal comorbidities, along with sarcopenia, has been evidenced to be associated with lean MASH. Genetic predispositions accompanying lifestyle and environmental factors contribute to disease initiation and progression. The genetic influence in pathophysiology indicated the significant contributions of the following genes: PNPLA3, TM6SF2, APOB, LIPA, MBOAT7, and HSD17B13, and the impact of their disease-specific variants in the development of obesity-independent MASH. The epigenetic modifications exhibited differential DNA methylation patterns in the genes involved in lipid metabolism, particularly hypomethylation of PEMT. Diet-induced and genetic animal models of lean MASH, including Slc: Wistar/ST rats, PPAR-α, PTEN, and MAT1A knockout mice models, are indicated to be pivotal in the exploration of disease progression and observing the effect of therapeutic interventions. This comprehensive review comprises the molecular and genetic pathophysiology, molecular diagnostics, and therapeutic aspects of lean MASH to enunciate a diagnostic approach that combines detailed clinical phenotyping regarding genomic analysis.

Therapeutic landscape of metabolic dysfunction-associated steatohepatitis (MASH)

Metabolic dysfunction-associated steatotic liver disease (MASLD) and its severe subgroup metabolic dysfunction-associated steatohepatitis (MASH) have become a global epidemic and are driven by chronic overnutrition and multiple genetic susceptibility factors. The physiological outcomes include hepatocyte death, liver inflammation and cirrhosis. The first therapeutic for MASLD and MASH, resmetirom, has recently been approved for clinical use and has energized this therapeutic space. However, there is still much to learn in clinical studies of MASH, such as the scale of placebo responses, optimal trial end points, the time required for fibrosis reversal and side effect profiles. This Review introduces aspects of disease pathogenesis related to drug development and discusses two main therapeutic approaches. Thyroid hormone receptor-β agonists, such as resmetirom, as well as fatty acid synthase inhibitors, target the liver and enable it to function within a toxic metabolic environment. In parallel, incretin analogues such as semaglutide improve metabolism, allowing the liver to self-regulate and reversing many aspects of MASH. We also discuss how combinations of therapeutics could potentially be used to treat patients.

What is the role of nonalcoholic fatty liver disease in pulmonary carcinoma development?

This article summarizes the epidemiological characteristics and clinical manifestations of nonalcoholic fatty liver disease (NAFLD). The incidence of NAFLD has been increased dramatically and become the leading cause of chronic liver disease worldwide. In addition to its adverse outcomes of liver fibrosis, cirrhosis, and hepatocellular carcinoma, and related complications, NAFLD has recently been found to be associated with the high-risk extrahepatic carcinomas, such as various types of lung cancer (i.e., lung adenocarcinoma, squamous cell carcinoma, and small cell lung cancer). The presence of hepatic steatosis also predisposes lung cancer to liver metastasis, but has better response to immune checkpoint inhibitors. Whether other factors (i.e., gender, smoking, etc.) are associated with NAFLD and lung cancer remains controversial. We also comment on the reciprocal relationships between NAFLD and components of metabolic syndrome. Most metabolic syndrome components are suggested to facilitate lung cancer development via activating insulin/insulin-like growth factor axis. In addition, suppressed anti-tumor immunity and accelerated tumor progression could be attributed to the cell-specific metabolic reprogramming in condition of high-fat diet and related obesity. These findings may reveal the role of NAFLD in pulmonary carcinoma and help develop new treatment strategies for this disease.

Appendicular skeletal muscle mass is associated with metabolic dysfunction-associated steatotic liver disease severity in young men: a cross-sectional and longitudinal study

BACKGROUND AND AIM

Although appendicular skeletal muscle mass (ASM) has been linked to the severity of hepatic steatosis, investigations of its correlation among younger age groups are lacking. We aimed to elucidate the role of ASM in determining the severity of metabolic dysfunction-associated steatotic liver disease (MASLD) in younger patients.

METHODS

Retrospective data were collected from patients younger than 35 years who visited the Armed Forces Goyang Hospital between June 2022 and February 2024. Steatosis presence was determined by a controlled attenuation parameter score ≥ 250 dB/m, and significant fibrosis was identified with liver stiffness measurement > 8.0 kPa. ASM was measured using multifrequency bioelectrical impedance analysis (InBody 620).

RESULTS

Of 910 participants, 630 were diagnosed with MASLD. Patients with MASLD had lower ASM/fat mass (ASM/F) (1.02 vs. 1.91; p < 0.001), ASM/body mass index (BMI) (0.91 vs. 1.04/m2; p < 0.001), and ASM/body weight (ASM/W) (29.5% vs. 33.8%; p < 0.001) than non-MASLD patients. Additionally, ASM/F, ASM/BMI, and ASM/W significantly decreased with worsening steatosis severity and were notably lower in patients with significant fibrosis. Among 107 patients with MASLD who underwent two examinations with a median interval of 6.0 months, those with increased ASM/F showed a higher proportion of steatosis regression and a lower proportion of steatosis worsening than those with decreased ASM/F (steatosis regression, 43.1% vs. 22.9%; worsening, 11.1% vs. 28.6%; p = 0.031). All three ASM indices were significant factors in steatosis regression during the study period.

CONCLUSIONS

ASM is associated with the severity of steatosis and significant fibrosis in MASLD in young adults < 35 years.

Possible Use of Body Surface Area Value for Estimating Skeletal Muscle Mass in Chronic Liver Disease

Background/Objectives: Sarcopenia is an important clinical feature of patients with chronic liver disease (CLD). However, special devices are required to determine skeletal muscle mass. We evaluated the usefulness of body surface area (BSA) for estimating muscle mass and diagnosing sarcopenia in patients with CLD. Methods: We retrospectively studied 1889 Japanese patients with CLD who underwent bioimpedance analysis (BIA) (training cohort, n = 983; validation cohort, n = 906). The optimal cutoff values for predicting low skeletal muscle mass index (SMI) were determined using ROC analysis. We also assessed 1229 patients whose BSA and grip strength (GS) data were obtained on the same day and evaluated the diagnostic performance of the determined cutoff values of BSA for the diagnosis of sarcopenia. Results: In the training cohort, a strong correlation was observed between the SMI and BSA (r = 0.883, p < 0.0001). The cutoff values of BSA for predicting low SMI were 1.68 m2 for men and 1.48 m2 for women. Regarding the presence of low SMI, 776 (78.9%) and 730 (80.5%) patients were correctly diagnosed in the training and validation cohorts, respectively. The sensitivity and specificity of the combination of BSA and GS for sarcopenia were 82.7% and 97.1%, respectively, and 1175 patients (95.6%) were correctly diagnosed. Conclusions: BSA was highly correlated with SMI, suggesting that BSA could facilitate noninvasive estimation of low skeletal muscle mass in patients with CLD.

Metabonomic Biomarkers of Plaque Burden and Instability in Patients With Coronary Atherosclerotic Disease After Moderate Lipid-Lowering Therapy

BACKGROUND

Contemporary risk assessment in patients with coronary atherosclerotic disease (CAD) often relies on invasive angiography. However, we aimed to explore the potential of metabolomic biomarkers in reflecting residual risk in patients with CAD after moderate lipid-lowering therapy.

METHODS AND RESULTS

We analyzed serum metabolomic profile among 2560 patients with newly diagnosed CAD undergoing moderate lipid-lowering therapy, through nuclear magnetic resonance spectroscopy and quantified 175 metabolites, predominantly lipoproteins and their components. CAD severity was evaluated using Gensini score for plaque burden and circulating cardiac troponin T levels for plaque instability. The association of metabolites with CAD severity was examined using multivariate linear regression, and the underlying potential causality was explored using a 2-sample Mendelian randomization approach. Two composite metabolomic indices were constructed to reflect CAD severity using least absolute shrinkage and selection operator linear regression, and their associations with risk of major adverse cardiac events during a median follow-up of 3.8 years were evaluated using Cox models. Our investigation revealed that triglycerides and apolipoprotein B in low-density lipoprotein particles displayed stronger associations with CAD severity compared with the clinically used low-density lipoprotein cholesterol marker. In large high-density lipoprotein, components like cholesterol, cholesterol esters, triglyceride, apolipoprotein A1/A2 showed inverse associations with CAD severity. Certain metabolites, including apolipoprotein B and dihydrothymine, showed a putative causal link with Gensini score. Notably, per standard deviation increase in Gensini score-based metabolomic index was associated with 14.8% higher major adverse cardiac event risk (hazard ratio, 1.148 [95% CI, 1.018-1.295]) independent of demographic factors, medication use, and disease status.

CONCLUSIONS

Our findings highlight the potential of nuclear magnetic resonance-based metabolomics in identifying novel biomarkers of plaque burden and instability. Metabolites related to plaque burden may facilitate noninvasive assessment of CAD prognosis.

Sarcopenia as a Risk Factor for Mortality in NAFLD: How Should We Diagnose It?

OBJECTIVES

Sarcopenia increases the risk of nonalcoholic steatohepatitis (NASH) and cirrhosis in patients with nonalcoholic fatty liver disease (NAFLD). Subsequently, poorly managed NAFLD can result in adverse health outcomes. Lifestyle interventions are effective for both NAFLD and sarcopenia; however, diagnosis of sarcopenia in this population is not well defined. This review aimed to examine current methods to diagnose sarcopenia in NAFLD patients.

METHODS

MEDLINE, EMBASE, and CINAHL databases were searched for articles published until July 2023 using the terms "Non-alcoholic fatty liver disease," "NAFLD," "fatty liver," "sarcopenia," and "myoatrophy." Studies were excluded if they included pediatric populations, did not diagnose both sarcopenia and NAFLD, or included patients with alternate causes of liver disease.

RESULTS

Twenty studies, predominantly from Asian countries (14 [70.0%]), involving 68 848 participants (45.5% females) were included. In 15 studies, most participants had a BMI > 25 kg/m2. Heterogeneity in the tools used to diagnose NAFLD was identified, with abdominal ultrasound being the most commonly used. European, Asian, and Australasian Sarcopenia Working Groups had differing diagnostic definitions of sarcopenia. Of the three potential diagnostic elements of sarcopenia (muscle mass, strength, function), all studies measured muscle mass, commonly through bioelectrical impedance analysis (12 [60.0%]). Seven studies (35.0%) measured muscle strength, with the majority (n = 6) utilizing hand grip strength. Four (20.0%) measured muscle function, through gait speed or a timed up-and-go test.

CONCLUSIONS

The lack of standardization in sarcopenia diagnosis for NAFLD patients is concerning. A consistent definition is necessary to prevent this comorbidity from being overlooked, improve care, and outcomes.

Clinical Characteristics of Sarcopenia in Nonalcoholic Fatty Liver Disease: A Systemic Scoping Review

INTRODUCTION

This systematic scoping review aimed to synthesize existing research findings on the clinical manifestations in patients with nonalcoholic fatty liver disease (NAFLD) and sarcopenia.

METHODS

Adhering to scoping review guidelines, we comprehensively searched five databases for literature on sarcopenia's clinical manifestations in NAFLD patients from December 2013 to December 2023, meticulously compiling and synthesizing the findings.

RESULTS

A total of 312 articles were identified, with 9 studies included in the final review. Of these, 90% were cross-sectional investigations, with 70% from Asian cohorts. Comparative analysis between patients solely afflicted with NAFLD and those additionally experiencing sarcopenia revealed discernible trends. Individuals with both conditions tended to be older, have a higher body mass index, and show a higher prevalence among females, underscoring the influence of unhealthy lifestyles and obesity. Furthermore, comorbidities like metabolic syndrome, hypertension, and diabetes have been implicated in sarcopenia manifestation among NAFLD patients. Nonetheless, the lack of standardized diagnostic criteria and patterns poses an ongoing clinical challenge for this subgroup.

CONCLUSIONS

Our review highlights distinct clinical characteristics evident in NAFLD patients with sarcopenia. However, comprehensive investigations remain scarce, impeding accurate early detection and intervention. Future research should prioritize bridging these gaps and fostering enhanced clinical management strategies.

Metabolic dysfunction associated fatty liver disease in healthy weight individuals

Metabolic dysfunction associated fatty liver disease (MAFLD) is an increasing public health problem, affecting one third of the global population. Contrary to conventional wisdom, MAFLD is not exclusive to obese or overweight individuals. Epidemiological studies have revealed a remarkable prevalence among healthy weight individuals, leading investigations into the genetic, lifestyle, and dietary factors that contribute to the development of MAFLD in this population. This shift in perspective requires reconsideration of preventive strategies, diagnostic criteria and therapeutic approaches tailored to address the unique characteristics of MAFLD healthy weight individuals. It also underscores the importance of widespread awareness and education, within the medical community and among the general population, to promote a more inclusive understanding of liver metabolic disorders. With this review, we aim to provide a comprehensive exploration of MAFLD in healthy weight individuals, encompassing epidemiological, pathophysiological, and clinical aspects.

The prevalence and effects of sarcopenia in patients with metabolic dysfunction-associated steatotic liver disease (MASLD): A systematic review and meta-analysis

BACKGROUND AND AIMS

Sarcopenia is a common complication in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). However, the prevalence and its impact on the survival of sarcopenia in patients with MASLD is unknown. In this study, we aimed to assess the prevalence and effects of sarcopenia in patients with MASLD.

METHODS

Systematic review and meta-analysis of full texts of relevant studies were searched from inception until June 12, 2024 in five databases (PubMed, Cochrane Library, Embase, Web of Science, and the China National Knowledge Infrastructure). Next, we assessed the prevalence of sarcopenia in MASLD, and calculated the ORs and HRs between sarcopenia and MASLD based on the adjusted data from individual studies. Statistical analyses were performed using Stata 11.0.

RESULTS

Of the 2984 records considered, 29 studies recruiting 63,330 patients were included. The pooled prevalence of sarcopenia in patients with MASLD was 23.5% overall (95% CI; 19.1%-27.9%, I2 = 99.6%), and was higher in Asian patients, male, cross-sectional studies, when BIA were employed to measure muscle mass, one criterion of diagnosis sarcopenia, MASLD was diagnosed employing MRI, and moderate-quality studies. Sarcopenia was associated with MASLD patients (adjusted odds ratio [aOR] 2.08, 95% CI 1.58-2.74, I2 = 93.6%) with similar findings in subgroups stratified by age, study design, methods for measuring muscle mass, assessment method to detect sarcopenia, and study quality. The association between all-cause mortality further supports the association between sarcopenia and poor prognosis with MASLD (aHR 1.59, 95% CI 1.33-1.91, I2 = 0%).

CONCLUSIONS

Sarcopenia was strongly associated with MASLD progression and was a risk factor not only for MASLD pathogenesis but was also markedly correlated with MASLD-associated mortality.

MAFLD: an ideal framework for understanding disease phenotype in individuals of normal weight

The prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD) is significant, impacting almost one-third of the global population. MAFLD constitutes a primary cause of end-stage liver disease, liver cancer and the need for liver transplantation. Moreover, it has a strong association with increased mortality rates due to various extrahepatic complications, notably cardiometabolic diseases. While MAFLD is typically correlated with obesity, not all individuals with obesity develop the disease and a significant percentage of MAFLD occurs in patients without obesity, termed lean MAFLD. The clinical features, progression and underlying physiological mechanisms of patients with lean MAFLD remain inadequately characterized. The present review aims to provide a comprehensive summary of current knowledge on lean MAFLD and offer a perspective on defining MAFLD in individuals with normal weight. Key to this process is the concept of metabolic health and flexibility, which links states of dysmetabolism to the development of lean MAFLD. This perspective offers a more nuanced understanding of MAFLD and its underlying mechanisms and highlights the importance of considering the broader metabolic context in which the disease occurs. It also bridges the knowledge gap and offers insights that can inform clinical practice.

Prevalence and outcome of sarcopenia in non-alcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) includes a spectrum of conditions, progressing from mild steatosis to advanced fibrosis. Sarcopenia, characterized by decreased muscle strength and mass, shares common pathophysiological traits with NAFLD. An association exists between sarcopenia and increased NAFLD prevalence. However, data on the prevalence of sarcopenia in NAFLD and its impact on the outcomes of NAFLD remain inconsistent.

AIM

To analyze the prevalence and outcomes of sarcopenia in patients with NAFLD.

METHODS

We conducted a comprehensive search for relevant studies in MEDLINE, Embase, and Scopus from their inception to June 2023. We included studies that focused on patients with NAFLD, reported the prevalence of sarcopenia as the primary outcome, and examined secondary outcomes, such as liver fibrosis and other adverse events. We also used the Newcastle-Ottawa scale for quality assessment.

RESULTS

Of the 29 studies included, the prevalence of sarcopenia in NAFLD varied widely (1.6% to 63.0%), with 20 studies reporting a prevalence of more than 10.0%. Substantial heterogeneity was noted in the measurement modalities for sarcopenia. Sarcopenia was associated with a higher risk of advanced fibrosis (odd ratio: 1.97, 95% confidence interval: 1.44-2.70). Increased odds were consistently observed in fibrosis assessment through biopsy, NAFLD fibrosis score/body mass index, aspartate aminotransferase to alanine aminotransferase ratio, diabetes (BARD) score, and transient elastography, whereas the fibrosis-4 score showed no such association. Sarcopenia in NAFLD was associated with a higher risk of steatohepatitis, insulin resistance, cardiovascular risks, and mortality.

CONCLUSION

This systematic review highlights the critical need for standardized diagnostic criteria and measurement methods for sarcopenia in NAFLD patients. The variability in study designs and assessment methods for sarcopenia and liver fibrosis may account for the inconsistent findings. This review demonstrates the multidimensional impact of sarcopenia on NAFLD, indicating its importance beyond liver-related events to include cardiovascular risks, mortality, and metabolic complications.

Metabolic-associated fatty liver disease and sarcopenia: A double whammy

The prevalence of metabolic-associated fatty liver disease (MAFLD) has increased substantially in recent years because of the global obesity pandemic. MAFLD, now recognized as the number one cause of chronic liver disease in the world, not only increases liver-related morbidity and mortality among sufferers but also worsens the complications associated with other comorbid conditions such as cardiovascular disease, type 2 diabetes mellitus, obstructive sleep apnoea, lipid disorders and sarcopenia. Understanding the interplay between MAFLD and these comorbidities is important to design optimal therapeutic strategies. Sarcopenia can be either part of the disease process that results in MAFLD (e.g., obesity or adiposity) or a consequence of MAFLD, especially in the advanced stages such as fibrosis and cirrhosis. Sarcopenia can also worsen MAFLD by reducing exercise capacity and by the production of various muscle-related chemical factors. Therefore, it is crucial to thoroughly understand how we deal with these diseases, especially when they coexist. We explore the pathobiological interlinks between MAFLD and sarcopenia in this comprehensive clinical update review article and propose evidence-based therapeutic strategies to enhance patient care.

Relationship between neck vessel abnormalities and sarcopenia: results of a study examining trends in health and aging in western China

OBJECTIVE

To elucidate the association between cervical vascular abnormalities (high Crouse score, high carotid intima-media thickness [CIMT], high plaque score [PS]) and sarcopenia and its diagnostic elements.

STUDY DESIGN

This cross-sectional investigation selected patients from the Western China Health and Aging Trends Study (WCHAT) aged 60 years and older. High CIMT and high Crouse score was defined as values ≥ upper quartile cutoff. Moreover, PS ≥ 3 was set as an high PS. Sarcopenia diagnosis and the definition of sarcopenia diagnostic elements were based on the Asian Working Group on Sarcopenia (AWGS) 2019 consensus. Lastly, associations between high Crouse score, high PS, high CIMT, and sarcopenia and its diagnostic elements were assessed using logistic regression.

RESULT

In all, we recruited 932 subjects in this study, among which, 138 people (14.81%) were diagnosed with sarcopenia. The rates of high Crouse score (sarcopenia vs. non-sarcopenia: 37.68% vs. 23.30%, P < 0.001) and high PS (sarcopenia vs. non-sarcopenia: 34.78% vs. 18.39%, P < 0.001) in subjects with sarcopenia were higher than those in subjects without sarcopenia. Logistic regression analysis and the correction of possible confounding factors showed that high Crouse score and high PS were related to sarcopenia (high Crouse score: OR = 1.573; 95%CI: 1.032-2.4; high PS: OR = 1.845; 95%CI: 1.195-2.851). Further analysis indicated that high Crouse score were associated with low muscle mass (OR = 1.403; 95%CI: 1.002-1.966) and low physical function (OR = 1.93; 95%CI: 1.3-2.866). High PS was found to be related to low physical function (OR = 1.83; 95%CI: 1.209-2.771).

CONCLUSION

While both high Crouse score and high PS are related to sarcopenia, further analysis showed that high Crouse score were mainly associated with low muscle mass and low physical function while high PS was associated with low physical function.

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.

Sarcopenia, sarcopenic obesity and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), sarcopenia and sarcopenic obesity (SO) are highly prevalent conditions that may coexist, especially in the aging population, without any approved pharmacologic treatment for all of them. There are multiple pathophysiologic mechanisms suggested to explain an association between NAFLD and sarcopenia or SO, including alterations in the adipokines, cytokines, hepatokines and myokines, which may interplay with other factors, such as aging, diet and physical inactivity. In clinical terms, most observational studies support an association between NAFLD and sarcopenia or SO; importantly, there are few cohort studies indicating higher mortality in patients with NAFLD and sarcopenia. Their association also bears some treatment considerations: for example, pioglitazone or vitamin E, suggested as off label treatment for selected patients with nonalcoholic steatohepatitis, may be recommended in the coexistence of sarcopenia or SO, since limited evidence did not show adverse effects of them on sarcopenia and abdominal obesity. In this review, evidence linking sarcopenia and SO with NAFLD is summarized, with a special focus on clinical data. A synopsis of the major pathophysiological links between NAFLD and sarcopenia/SO is initially presented, followed by selected clinical studies and, finally, treatment considerations in patients with NAFLD and sarcopenia or SO are discussed.

Lean nonalcoholic fatty liver disease and sarcopenia

Nonalcoholic fatty liver disease (NAFLD) has become one of the most common chronic liver diseases in the world. The risk factor for NAFLD is often considered to be obesity, but it can also occur in people with lean type, which is defined as lean NAFLD. Lean NAFLD is commonly associated with sarcopenia, a progressive loss of muscle quantity and quality. The pathological features of lean NAFLD such as visceral obesity, insulin resistance, and metabolic inflammation are inducers of sarcopenia, whereas loss of muscle mass and function further exacerbates ectopic fat accumulation and lean NAFLD. Therefore, we discussed the association of sarcopenia and lean NAFLD, summarized the underlying pathological mechanisms, and proposed potential strategies to reduce the risks of lean NAFLD and sarcopenia in this review.

Mechanisms of non-alcoholic fatty liver disease development in normal-weight individuals

While non-alcoholic fatty liver disease (NAFLD) without inflammation or fibrosis is considered a relatively 'benign' disease, non-alcoholic steatohepatitis (NASH), by contrast, is characterized by marked inflammation in addition to lipid accumulation, and may include fibrosis, progression to cirrhosis and hepatocellular carcinoma. Obesity and type II diabetes are frequently associated with NAFLD/NASH; however, a significant number of lean individuals may develop these diseases. Little attention has been paid to the causes and mechanisms contributing to NAFLD development in normal-weight individuals. One of the main causes of NAFLD in normal-weight individuals is the accumulation of visceral and muscular fat and its interaction with the liver. Myosteatosis (triglyceride accumulation in the muscle) induces a loss of muscle by reducing blood flow and insulin diffusion, contributing to NAFLD. Normal-weight patients with NAFLD exhibit higher serum markers of liver damage and C-reactive protein levels, as well as more pronounced insulin resistance, compared to healthy controls. Notably, increased levels of C-reactive protein and insulin resistance are strongly correlated with the risk of developing NAFLD/NASH. Gut dysbiosis has also been associated with NAFLD/NASH progression in normal-weight individuals. More investigation is required to elucidate the mechanisms leading to NAFLD in normal-weight individuals.