High-Fat Diet Induces MASLD and Adipose Tissue Changes in Obesity-Resistant Rats.

BACKGROUND/AIMS: Obesity Resistance (OR) is characterized by limited weight gain and reduced fat accumulation despite an obesogenic diet. However, the metabolic risk, particularly regarding Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), remains unclear. The current study aims to investigate the presence of MASLD, as well as metabolic parameters and morphological aspects of adipose tissues in obesity-resistant (OR) R rats fed a high-fat diet (HFD).

METHODS

ale Wistar rats (n=71) were initially randomized into two groups: a) standard diet (SD, n=35) and b) high-fat diet (HFD, n=36). The protocol was performed for 14 weeks, including 4 weeks of induction and 10 weeks of exposure to obesity. Subsequently, after applying the tertile classification criterion, the animals were redistributed into three groups: a) control (C, n=12), fed a standard diet; b) obesity-prone (OP, n=12); and c) OR (n=12). Body weight evolution, adiposity, nutritional behavior, metabolic markers, and liver morphology were assessed, along with the staging of MASLD.

RESULTS

OR rats exhibited lower body weight, total fat pads, and leptin compared to OP but higher values than C. MASLD was observed in 50% of OR animals, while 37.5% progressed to metabolic dysfunction-associated steatohepatitis (MASH). OP rats had a higher incidence of MASH (87.5%).

CONCLUSION

Chronic HFD exposure in OR rats lead to metabolic changes and MASLD development, including MASH, demonstrating that OR does not protect against HFD-induced hepatic alterations.