Weight loss in MASLD restores the balance of liver fatty acid sources
Jennifer E. Lambert, … , Thomas Rogers, Elizabeth J. Parks
Jennifer E. Lambert, … , Thomas Rogers, Elizabeth J. Parks
Published May 1, 2025
Citation Information: J Clin Invest. 2025;135(9):e174233. https://doi.org/10.1172/JCI174233.
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Clinical Research and Public Health Hepatology Metabolism

Weight loss in MASLD restores the balance of liver fatty acid sources

Abstract

BACKGROUND Lipogenesis contributes substantially to the pathological accumulation of intrahepatic triacylglycerol (IHTG) in metabolic dysfunction–associated steatotic liver disease (MASLD). Since hepatic lipogenesis is highly sensitive to energy intake, we hypothesized that mechanisms of MASLD regression induced by weight loss would be driven by a marked reduction in the lipogenic pathway.METHODS Overweight adults with high liver fat (HighLF; n = 9; IHTG ≥ 5.6% measured by 1H-magnetic resonance spectroscopy) or low (normal) liver fat (LowLF; n = 6; IHTG < 5.6%) received dietary counseling for 6 months and underwent comprehensive metabolic phenotyping during inpatient studies that captured fasting and fed states. Multiple stable isotopes were used to assess the contribution of lipogenesis, free fatty acids (FFAs), and dietary fat to IHTG.RESULTS Body weight loss (–10% ± 2%) reduced IHTG in individuals with MASLD (19.4% ± 3.6% to 4.5% ± 2.1%, P < 0.001). Insulin sensitivity improved significantly (46%, P < 0.01), while fasting FFA flux from adipose tissue was not different. VLDL-triacylglycerol (VLDL-TG) concentrations fell by 38% (P = 0.02) because of a 67% reduction in contribution from lipogenesis (P = 0.02), whereas the absolute contributions from FFAs and dietary fat to VLDL-TG were not different. Reduced lipogenesis was significantly associated with loss of IHTG.CONCLUSION These data underscore the primary role of lipogenesis in MASLD pathology and highlight the importance of controlling this pathway through treatment strategies.TRIAL REGISTRATION ClinicalTrials.gov (NCT01371396).FUNDING National Institutes of Health (NIH) grant RL1DK081187; Task Force for Obesity Research at Southwestern (TORS) NIH UL1DE019584; and Clinical and Translational Science Award NIH/National Center for Advancing Translational Sciences UL1-RR024982.

Authors

Jennifer E. Lambert, Maria A. Ramos-Roman, Maressa J. Valdez, Jeffrey D. Browning, Thomas Rogers, Elizabeth J. Parks

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Figure 8

Relationships between changes in liver fat and reductions in VLDL-TG, insulin sensitivity, and lipogenesis.

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Relationships between changes in liver fat and reductions in VLDL-TG, in...
(A) Arrows depict the magnitude of absolute changes in liver fat and plasma VLDL-TG concentrations for HighLF (n = 9) and LowLF (n = 6) subjects. (B) For all subjects combined, the greater the improvements in insulin sensitivity (assessed by the insulin sensitivity index via the i.v. glucose tolerance test), the greater the reductions in fasting VLDL-TG palmitate %DNL (assessed by Pearson’s correlation). For the HighLF subjects, stepwise regression coefficients are presented for predictors of the absolute (Abs) change in IHTG with weight loss (C), and for predictors of the final level of IHTG at follow-up (D). For example, in C, large reductions in IHTG (follow-up minus baseline) were predicted by greater baseline IHTG levels and greater increases in insulin sensitivity.