Weight Change and the Development of Nonalcoholic Fatty Liver Disease in Metabolically Healthy Overweight Individuals

Metabolically Healthy Obesity and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Navigating the Controversies in Disease Development and Progression

PURPOSE OF REVIEW

The natural course of metabolic dysfunction-associated steatotic liver disease (MASLD) in the population with metabolically healthy obesity (MHO) has not been adequately explored. In the present narrative review, we summarize the evidence regarding the association between MHO and MASLD prevalence, incidence and progression.

RECENT FINDINGS

Cross-sectional, population-based, cohort studies have shown an increased prevalence of hepatic steatosis and fibrosis in subjects with MHO compared with metabolically healthy non-obese individuals (MHNO). In large-scale longitudinal cohort studies among metabolically healthy subjects, increasing body mass index (BMI) has been found to be independently associated with an increased incidence of MASLD and progressive hepatic fibrosis over a mean follow-up period of 2.2-7.7 years. With regard to advanced MASLD, the prevalence of steatohepatitis and clinically significant liver fibrosis is lower in MHO compared with subjects with metabolically unhealthy obesity (MUO). The presence of MASLD has been proposed as a strong risk factor for metabolic health deterioration in MHO. Furthermore, subjects with MHO and MASLD display an elevated 10-year cardiovascular risk and a three-fold increased risk of incident diabetes compared with MHO without MASLD. MASLD may also predict the failure to convert from MUO to MHO after a weight loss intervention.

Genetic Risk, BMI Status, BMI Change Patterns, and the Risk of Steatotic Liver Disease and Liver Enzyme Elevation in Chinese Adults

Background/Objectives: Whether an increased genetic risk of steatotic liver disease (SLD) can be offset by maintaining a healthy weight remains unknown. We aimed to clarify the associations among the body mass index (BMI) and its change patterns with SLD and assess whether genetic susceptibility can modify these associations in Chinese people. Methods: A total of 10,091 and 6124 participants from the Health Omics Preventive Examination (HOPE) Program were enrolled in cross-sectional and follow-up analyses, respectively. BMI change patterns were defined according to the BMI at baseline and the last follow-up visit. Genetic risk was estimated using the polygenic risk score (PRS) derived from variants in PNPLA3, TM6SF2, MBOAT7, and GCKR. Data were analyzed using logistic regression models and Cox proportional-hazards models. Results: The analyses of the BMI and genetic risk simultaneously showed a dose-response association with the risk of SLD (p-trend < 0.001). Significant interactions between BMI and PRS were found for alanine aminotransferase (ALT) elevation (p = 0.007) and aspartate aminotransferase (AST) elevation (p < 0.001). Weight loss led to a 71%, 60%, and 67% lower risk of SLD, ALT elevation, and AST elevation, compared with stable overweight/obesity. A significant interaction between the genetic risk and BMI change patterns in ALT elevation was observed (p = 0.008). The absolute risk reductions associated with weight loss were greater for participants at a high genetic risk (26.60, 12.29, and 9.31 per 100 person years for SLD, ALT elevation, and AST elevation, respectively). Conclusions: Maintaining a healthy weight reduces the liver injury risk among all individuals, and the risk reduction is greater among the subset with a high genetic risk of SLD.

Association between weight change, waist circumference change, and the risk of nonalcoholic fatty liver disease in individuals with metabolically healthy overweight or obesity and metabolically unhealthy overweight or obesity

BACKGROUND

This study aimed to explore and compare the effect of weight change, and waist circumference (WC) change, on the risk of nonalcoholic fatty liver disease (NAFLD) in individuals with metabolically healthy overweight or obesity (MHOW/O) and metabolically unhealthy overweight or obesity (MUOW/O) in a health check-up cohort in China.

METHODS

5625 adults with overweight or obesity, and free from NAFLD at baseline were included. Metabolically healthy was defined as not having any components of metabolic syndrome. Weight/WC changes were calculated as the relative difference between the first and second visits of check-up. NAFLD was assessed based on abdominal ultrasound.

RESULTS

During a median follow-up of 2.1 (IQR: 1.1-4.3) years, 1849 participants developed NAFLD. In MHOW/O participants, the multivariable adjusted HRs (95 % CIs) for NAFLD in weight change ≤ -5.0 %, and - 4.9-- 1.0 % were 0.36 (0.23-0.59), 0.59 (0.43-0.80), respectively, compared to the weight stable group (-0.9% to 0.9 %). The corresponding HRs (95 % CIs) for the association between WC change (≤ 6.0 %, - 5.9 to -3.0 %) and NAFLD in MHOW/O participants were 0.41 (0.27-0.62), and 0.74 (0.54-1.01), respectively, compared to the WC stable group (-2.9-2.9 %). Similar patterns were observed in MUOW/O participants. A more marked gradient of cumulative incidence of NAFLD across weight/WC change categories was observed in MHOW/O than in MUOW/O individuals.

CONCLUSIONS

A more evident association between weight/WC loss and risk of NAFLD was observed in MHOW/O than in MUOW/O individuals. Our findings indicate the practical significance of encouraging all individuals with overweight and obesity to achieve a clinically relevant level of weight/WC loss to prevent NAFLD, even among metabolic healthy groups.

The effects of weight loss and improved metabolic health status on the risk of non-alcoholic fatty liver disease-results from a prospective cohort in China

BACKGROUND

The impact of weight loss and/or improved metabolic status on the risk of non-alcoholic fatty liver disease (NAFLD) has yet to be determined.

METHODS

A total of 35,322 participants without NAFLD were followed. NAFLD risk was compared between consistently metabolically healthy non-obese (MHNO) and non-MHNO who lost weight to become non-obese and/or improved their metabolic health, using Cox proportional hazards and logistic regression models.

RESULTS

Following 148,186 person-years, 8,409 participants had onset NAFLD, with an incidence rate of 56.75 (95% CI: 55.57, 57.94) per 1,000 person-years. Metabolically healthy obese (MHO), metabolically unhealthy obese (MUO), and metabolically unhealthy non-obese (MUNO) at baseline were associated with increased NAFLD risk, with hazard ratios of 4.48 (95%CI:4.24, 4.73), 8.85 (95%CI:7.95, 9.84), and 10.70 (95%CI:9.73, 11.78). Weight loss and/or metabolic status improvements could significantly reduce NAFLD risk by 79.46 to 41.46%. Specifically, after weight loss from MHO to MHNO, the reduction in NAFLD risk [OR decreased from 12.01 (95%CI:9.40, 15.35) to 4.14 (95%CI:3.08, 5.57)] was greater than that of the MUNO subgroup whose metabolic status improved to MHNO [OR decreased from 5.53 (95%CI:5.15, 5.94) to 2.71 (95%CI:2.50, 3.93)]. In the MUO subgroup, the group with the greatest risk reduction of NAFLD was the weight and metabolic state both improvement group [MUO to MHNO, OR decreased from 22.74 (95%CI:17.61, 29.37) to 4.67 (95%CI:3.05, 7.16)], followed by the weight loss only group [MUO to MUNO, OR decreased to 6.83 (95%CI:4.87, 9.57)], and finally the group with the least and insignificant risk reduction was the metabolic state improvement group [MUO to MHO, OR decreased to 13.38 (95%CI:9.17,19.53)]. NAFLD risk was negatively correlated with the duration of improvement (p < 0.001).

CONCLUSION

Individuals with non-MHNO were more likely to develop NAFLD than those with consistent MHNO, but metabolic improvements and weight loss can alleviate the risk. Their NAFLD risk was negatively correlated with improvement duration. However, it remained higher than in individuals with consistent MHNO at an average follow-up of 4.2 years.

Nonalcoholic Fatty Liver Disease: A Unique Entity or Part of the Metabolic Syndrome or Both

Nonalcoholic fatty liver disease (NAFLD) is a global public health problem. NAFLD is bidirectionally correlated with metabolic syndrome, which includes obesity, type 2 diabetes, hypertension, and dyslipidemia as major components. The presence of metabolic syndrome is associated with a higher prevalence of NAFLD, and vice versa. Also, the presence of metabolic syndrome in patients with NAFLD has been linked to a higher risk of cardiovascular diseases, liver-related complications, extrahepatic malignancies, and mortality, and possibly vice versa. Multidisciplinary care pathways including lifestyle modifications, control of metabolic risk, and potentially beneficial treatments are important to improve the clinical outcomes of patients with NAFLD.

Effect of cumulative body mass index exposure and long-term related change on incident non-alcoholic fatty liver disease

BACKGROUND

To evaluate the association between cumulative body mass index (BMI) and long-term BMI change with non-alcoholic fatty liver disease (NAFLD).

METHODS

We included 19 477 adult participants (12 556 men and 6921 women) from the Kailuan study from January 2006 to December 2013. Cumulative BMI was assessed using a quadratic mixed-effects method by sex before the index year; then, the NAFLD outcome was followed till December 2019. The long-term BMI change was calculated as the percentage change in average cumulative BMI from the baseline BMI.

RESULTS

During a median follow-up of 5.63 years, 6229 individuals developed incident NAFLD. Independent of baseline BMI, the NAFLD risk escalated with the cumulative BMI with adjusted hazard ratios (HRs) (95% confidence interval [CI]) of 1.60 (1.48-1.73) and 2.28 (2.06-2.53) for the intermediate tertile and the highest tertile (P_trend  <0.001). The association is amplified in women and the young. Compared to a stable weight (BMI change: -3% to 3%), NAFLD risk increased in the baseline BMI < 24 kg/m² group with weight gain (BMI change: >3%) and decreased in BMI ≥24 kg/m² group with weight loss (BMI change: <-3%) for men and women. However, we only observed a decreased NAFLD risk in men (HR: 0.82, 95% CI: 0.69-0.97) with BMI < 24 kg/m² and weight loss.

CONCLUSIONS

Monitoring cumulative BMI may help to identify high-risk NAFLD populations. The association between weight gain or loss varies by sex and baseline BMI, suggesting the importance of individualized weight management for NAFLD prevention.

Historical Changes in Weight Classes and the Influence of NAFLD Prevalence: A Population Analysis of 34,486 Individuals

Background: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease globally in tandem with the growing obesity epidemic. However, there is a lack of data on the relationship between historical weight changes 10 years ago and at present on NAFLD prevalence at the population level. Therefore, we sought to evaluate the relationship between weight classes and the prevalence of NAFLD. Methods: Data were used from the United States National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. Univariate and multivariate general linear model analyses were used to obtain risk ratio (RR) estimations of NAFLD events. Results: In total, 34,486 individuals were analysed, with those who were lean at both time points as the control group. Overweight (RR: 14.73, 95%CI: 11.94 to 18.18, p < 0.01) or obese (RR: 31.51, 95%CI: 25.30 to 39.25, p < 0.01) individuals at both timepoints were more likely to develop NAFLD. Residual risk exists where previously obese individuals became overweight (RR: 14.72, 95%CI: 12.36 to 17.52, p < 0.01) or lean (RR: 2.46, 95%CI: 1.40 to 4.31, p = 0.02), and previously overweight individuals who became lean (RR 2.24, 95%CI 1.42 to 3.54, p = 0.01) had persistent elevated risk of developing NAFLD despite weight regression. Sensitivity analysis identified that a higher proportion of individuals with regression in weight class were diabetics and Mexican Americans, while fewer African Americans saw weight-class regression. Conclusions: Residual risk exists in patients who lost weight despite the smaller magnitude of effect, and targeted weight reductions should still be used to mitigate the risk of NAFLD at the population level.

Research Progress on the Mechanism of Acupuncture Treatment for Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) represents the most common chronic liver disease worldwide, ranging from simple steatosis and nonalcoholic steatohepatitis to fibrosis, cirrhosis, and hepatocellular carcinoma. Acupuncture is a long-established treatment in traditional Chinese medicine. In recent years, increasing evidence has pointed to the effectiveness of acupuncture in the treatment of NAFLD, and a certain degree of progress has been made in the study of related mechanisms. However, previous systematic reviews have not discussed the characteristics and the related mechanisms of acupuncture in the treatment of NAFLD. Therefore, this review synthesizes the progress in research on acupuncture in the context of NAFLD treatment by the inhibition of inflammatory responses, regulation of lipid metabolism disorder, treatment of insulin resistance, antagonization of oxidative stress injury, and interference with endoplasmic reticulum stress. Overall, we sought to highlight the latest research results, potential applications, and ongoing challenges of this therapy.

Weight Change across Adulthood in Relation to Non-Alcoholic Fatty Liver Disease among Non-Obese Individuals

Background: To investigate the associations of weight change patterns across adulthood with the risk of non-alcoholic fatty liver disease (NAFLD). Methods: Using data from the National Health and Nutrition Examination Survey (NHANES) 2017–2018 cycle, we performed a retrospective cohort study with 2212 non-obese participants aged 36 years old over. Weight change patterns were categorized as “stable non-obese”, “early adulthood weight gain”, “middle and late adulthood weight gain” and “revert to non-obese” according to the body mass index (BMI) at age 25, 10 years prior and at baseline. Vibration-controlled transient elastography (VCTE) was performed to diagnose NAFLD. Modified Poisson regression was used to quantify the associations of weight change patterns with NAFLD. Results: Compared with participants in the “stable non-obese” group, those who gained weight at early or middle and late adulthood had an increased risk of NAFLD, with an adjusted rate ratio (RR) of 2.19 (95% CI 1.64–2.91) and 1.92 (95% CI 1.40–2.62), respectively. The risk of NAFLD in “revert to the non-obese” group showed no significant difference with the stable non-obese group. If the association of weight change and NAFLD was causal, we estimated that 73.09% (95% CI 55.62–82.93%) of incident NAFLD would be prevented if the total population had a normal BMI across adulthood. Conclusions: Weight gain to obese at early or middle and late adulthood was associated with an evaluated risk of NAFLD. A large proportion would have been prevented with effective weight intervention.