Although several studies have used fat-1 transgenic mouse model to investigate the effects of n-3 PUFAs on obesity, diabetes, and NAFLD [17,34,35,36,37,38,39,40], the present study is the first using the model to specifically investigate how n-3 PUFAs regulate brown fat function. This evidence concerns the gene FAT1 and metabolic dysfunction-associated steatotic liver disease.