Physical activity levels and hepatic steatosis: A longitudinal follow-up study in adults

Impact of lifestyle interventions on pathogenesis of nonalcoholic fatty liver disease

This editorial builds on the article titled “Establishment and validation of an adherence prediction system for lifestyle interventions in non-alcoholic fatty liver disease” by Zeng et al. We carried out a critical examination of nonalcoholic fatty liver disease (NAFLD) pathogenesis and how lifestyle interventions could facilitate disease resolution, particularly highlighting that non-alcoholic steatohepatitis (NASH) is a severe form of NAFLD. Our discussion details that weight loss is a pivotal factor in disease outcomes: A 3%-5% reduction is enough for resolution in 50% of non-obese individuals, while a 7%-10% reduction achieves similar benefits in obese individuals, as demonstrated by magnetic resonance spectroscopy. Additionally, the editorial underscores that such lifestyle changes are instrumental not only in resolving NAFLD but also in reversing hepatic steatosis and inflammation. These insights, derived from the research, emphasize the critical role of personalized lifestyle modifications in halting the progression of NAFLD to NASH and even reversing fibrosis, thus offering a template for effective patient management.

Poor cardiorespiratory fitness may be an indicator of more severe liver inflammation in non-alcoholic fatty liver disease patients

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is related to cardiovascular disease. Cardiorespiratory fitness (CRF) is an important indicator of cardiovascular health. Therefore, we aimed to evaluate the CRF of NAFLD patients.

METHODS

Cross-sectional study, including 32 patients with biopsy-proved NAFLD. The patients underwent ergometric test (ET) and six-minute walk test (6MWT) to determine CRF. The test results were compared to disease parameters and with each other.

RESULTS

Considering the ET, 20 (62.5%) patients had very poor or poor CRF, and in 12 (37.5%), it was regular or good. In the 6MWT, 13 (40.6%) individuals had poor CRF, in 12 (37.5%), it was very poor, and in seven (21.9%), regular. NAFLD activity score (NAS) ≥5 was observed in 12 (37.5%) individuals. Twelve (37.5%) patients were sedentary, 11 (34.4%), insufficiently active, and nine (28.1%), active. Obesity and liver inflammation on biopsy were associated with very poor/poor CRF. NAS ≥5 and sedentary lifestyle were independently associated with very poor/poor CRF by ET. Although mean VO2max values determined by both tests were similar, no correlation of VO2max determined by ET and 6MWT was observed, as occurred for the distance walked in 6MWT and values of metabolic equivalent (MET) determined by ET. There was no reproducibility between CRF determined by ET and 6MWT.

CONCLUSION

Most NAFLD patients had very poor or poor CRF. Severe liver injury (NAS ≥5) and sedentary lifestyle were independently associated with very poor/poor fitness, according to ET. No reproducibility was observed between the CRF defined by ET and 6MWT.

Metabolic and Risk Profiles of Lean and Non-Lean Hepatic Steatosis among US Adults

Hepatic steatosis can occur in lean individuals, while its metabolic and risk profiles remain unclear. We aimed to characterize the clinical and risk profiles of lean and non-lean steatosis. This cross-sectional study included 1610 patients with transient elastography-assessed steatosis. The metabolic and risk profiles were compared. Compared to their non-lean counterparts, lean subjects with steatosis had a lower degree of fibrosis (F0-F1: 91.9% vs. 80.9%), had a lower prevalence of diabetes (27.9% vs. 32.8%), dyslipidemia (54.7% vs. 60.2%) and hypertension (50.0% vs. 51.3%), and had higher levels of high-density lipoprotein cholesterol while lower fasting insulin and homeostatic model assessment for insulin resistance (all p < 0.05). Of the 16 potential risk factors, being Hispanic was associated with higher odds of non-lean steatosis but not with lean steatosis (odds ratio (OR): 2.07 vs. 0.93), while excessive alcohol consumption had a different trend in the ratio (OR: 1.47 vs.6.65). Higher waist-to-hip ratio (OR: 7.48 vs. 2.45), and higher waist circumference (OR: 1.14 vs. 1.07) showed a stronger positive association with lean steatosis than with non-lean steatosis (all P_{heterogeneity} < 0.05). Although lean individuals with steatosis presented a healthier metabolic profile, both lean and non-lean steatosis had a significant proportion of metabolic derangements. In addition, the etiological heterogeneity between lean and non-lean steatosis may exist.

Cardiometabolic disorders, inflammation and the incidence of non-alcoholic fatty liver disease: A longitudinal study comparing lean and non-lean individuals

BACKGROUND

There is limited knowledge about the risk of non-alcoholic fatty liver disease (NAFLD) associated with cardiometabolic disorders in lean persons. This study examines the contribution of cardiometabolic disorders to NAFLD risk among lean individuals and compares to non-lean individuals.

METHODS

We analyzed longitudinal data from 6,513 participants of a yearly voluntary routine health testing conducted at the Hospital Israelita Albert Einstein, Brazil. NAFLD was defined as hepatic ultrasound diagnosed fatty liver in individuals scoring below 8 on the alcohol use disorders identification test. Our main exposure variables were elevated blood glucose, elevated blood pressure (BP), presence of atherogenic dyslipidemia (AD, defined as the combination of elevated triglycerides and low HDL cholesterol) and physical inactivity (<150 minutes/week of moderate activity). We further assessed the risk of NAFLD with elevations in waist circumference and high sensitivity C-reactive protein (HsCRP).

RESULTS

Over 15,580 person-years (PY) of follow-up, the incidence rate of NAFLD was 7.7 per 100 PY. In multivariate analysis adjusting for likely confounders, AD was associated with a 72% greater risk of NAFLD (IRR: 1.72 [95% CI:1.32-2.23]). Elevated blood glucose (IRR: 1.71 [95%CI: 1.29-2.28]) and physical inactivity (IRR: 1.46 [95%CI: 1.28-1.66]) were also independently associated with increased risk of NAFLD. In lean individuals, AD, elevated blood glucose and elevated BP were significantly associated with NAFLD although for elevated blood glucose, statistical significance was lost after adjusting for possible confounders. Physical inactivity and elevations in HsCRP were not associated with the risk of NAFLD in lean individuals only. Among lean (and non-lean) individuals, there was an independent association between progressively increasing waist circumference and NAFLD.

CONCLUSION

Cardiometabolic risk factors are independently associated with NAFLD. However, there are significant differences in the metabolic risk predictors of NAFLD between lean and non-lean individuals. Personalized cardiovascular disease risk stratification and appropriate preventive measures should be considered in both lean and non-lean individuals to prevent the development of NAFLD.

Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has a global prevalence of 25% and is a leading cause of cirrhosis and hepatocellular carcinoma. NAFLD encompasses a disease continuum from steatosis with or without mild inflammation (non-alcoholic fatty liver), to non-alcoholic steatohepatitis (NASH), which is characterised by necroinflammation and faster fibrosis progression than non-alcoholic fatty liver. NAFLD has a bidirectional association with components of the metabolic syndrome, and type 2 diabetes increases the risk of cirrhosis and related complications. Although the leading causes of death in people with NAFLD are cardiovascular disease and extrahepatic malignancy, advanced liver fibrosis is a key prognostic marker for liver-related outcomes and overall mortality, and can be assessed with combinations of non-invasive tests. Patients with cirrhosis should be screened for hepatocellular carcinoma and oesophageal varices. There is currently no approved therapy for NAFLD, although several drugs are in advanced stages of development. Because of the complex pathophysiology and substantial heterogeneity of disease phenotypes, combination treatment is likely to be required for many patients with NAFLD. Healthy lifestyle and weight reduction remain crucial to the prevention and treatment of NAFLD.

NAFLD and Physical Exercise: Ready, Steady, Go!

Along with the increase in obesity and type 2 diabetes, the non-alcoholic fatty liver disease (NAFLD) incidence is escalating, thus becoming a leading cause of liver cirrhosis and a significant burden of liver-related outcomes. Since there is no pharmacotherapy available to address the NAFLD, the most effective solutions seem to be lifestyle changes centered on physical activity. Exercise could mediate its beneficial effects directly on the liver and indirectly via extrahepatic pathways, forming a dose-response relationship with NAFLD in terms of prevalence and disease severity. Health-enhancing physical activity (HEPA) levels are mainly needed to exert beneficial effects in obese subjects, while even a small amount of exercise can be beneficial for lean individuals to prevent NAFLD. This mini-review addresses three major points regarding physical activity and NAFLD: prevention, treatment, and extrahepatic benefits, offering recommendations on type and intensity of exercise in liver disease.

Aerobic Exercise in the Management of Metabolic Dysfunction Associated Fatty Liver Disease

Sedentarism is the pandemic of modern times. It is associated with several medical conditions including obesity, type 2 diabetes mellitus, cardiovascular diseases and also liver disease, particularly metabolic dysfunction associated fatty liver disease (MAFLD). In an era when MAFLD is the most prevalent chronic liver disease worldwide, whilst no pharmacological therapy has been approved for it, exercise has proved to be effective in improving liver steatosis. Interestingly, exercise decreases liver fat even in the absence of weight loss. The challenge for the clinician is to motivate the obese patient with MAFLD, and associated co-morbidities, who has crystallized a sedentary behavior, at times when every need is at the distance of a click on the Internet, and the entire world can be visited behind a screen. In this review, the aggregate evidence on the mechanisms and effects of exercise in the management of MAFLD is summarized, with simple recommendations for everyday clinical practice.

Physical Activity and Sedentary Time: Association with Metabolic Health and Liver Fat

Introduction/Purpose

To investigate whether (a) lower levels of daily physical activity (PA) and greater sedentary time accounted for contrasting metabolic phenotypes (higher liver fat/presence of metabolic syndrome [METS+] vs lower liver fat/absence of metabolic syndrome [METS−]) in individuals of similar body mass index and (b) the association of sedentary time on metabolic health and liver fat.

Methods

Ninety-eight habitually active participants (53 female, 45 male; age, 39 ± 13 yr; body mass index 26.9 ± 5.1 kg·m⁻²), underwent assessments of PA (SenseWear armband; wear time ~98%), cardiorespiratory fitness (V˙O₂ peak), body composition (magnetic resonance imaging and magnetic resonance spectroscopy) and multiorgan insulin sensitivity (oral glucose tolerance test). We undertook a) cross-sectional analysis comparing four groups: nonobese or obese, with and without metabolic syndrome (METS+ vs METS−) and b) univariate and multivariate regression for sedentary time and other levels of PA in relation to liver fat.

Results

Light, moderate, and vigorous PA did not account for differences in metabolic health between individuals, whether nonobese or obese, although METS+ individuals were more sedentary, with a higher number, and prolonged bouts (~1–2 h). Overall, sedentary time, average daily METS and V˙O₂ peak were each independently associated with liver fat percentage. Each additional hour of daily sedentary time was associated with a 1.15% (95% confidence interval, 1.14%–1.50%) higher liver fat content.

Conclusions

Greater sedentary time, independent of other levels of PA, is associated with being metabolically unhealthy; even in habitually active people, lesser sedentary time, and higher cardiorespiratory fitness and average daily METS is associated with lower liver fat.

Lifestyle modification in NAFLD/NASH: Facts and figures

The development of non-alcoholic fatty liver disease is closely linked to lifestyle factors, namely excessive caloric intake coupled with reduced physical activity and exercise. This review aims to examine the evidence behind lifestyle change as a tool to improve hepatic steatosis and liver histology in patients with non-alcoholic fatty liver disease/non-alcoholic steatohepatitis. Furthermore, potential barriers to adopting lifestyle changes and strategies to overcome these barriers in the clinical setting are discussed.