HFD causes an increase in mRNA levels of genes involved in lipid metabolism and a metabolic shift increasing lipid metabolism in MCT1+/+ but not in MCT1+/− mice. After 12 weeks of SD or HFD, liver mRNA expression levels for transcription factors PPARα and PPARγ, SREBP1, CHREB (A–D), for the enzyme involved in lipid metabolism FAS (E) or the mitochondrial lipid transporter CPT1 (F). n = 10 animals per condition. *represents differences due to diet, # represents differences between genotypes during HFD. * or #: p < 0.05; ** or ##: p < 0.01; *** or ###: p < 0.001.