A ketogenic diet increases brown adipose tissue mitochondrial proteins and UCP1 levels in mice

We evaluated the effects of feeding a ketogenic diet (KD) for a month on general physiology with emphasis on brown adipose tissue (BAT) in mice. KD did not reduce the caloric intake, or weight or lipid content of BAT. Relative epididymal fat pads were 40% greater in the mice fed the KD (P = 0.06) while leptin was lower (P < 0.05). Blood glucose levels were 30% lower while D-β-hydroxybutyrate levels were about 3.5-fold higher in the KD group. Plasma insulin and leptin levels in the KD group were about half of that of the mice fed NIH-31 pellets (chow group). Median mitochondrial size in the interscapular BAT (IBAT) of the KD group was about 60% greater, whereas the median lipid droplet size was about half of that in the chow group. Mitochondrial oxidative phosphorylation proteins were increased (1.5-3-fold) and the uncoupling protein 1 levels were increased by threefold in mice fed the KD. The levels of PPARγ, PGC-1α, and Sirt1 in KD group were 1.5-3-fold while level of Sirt3 was about half of that in the chow-fed group. IBAT cyclic AMP levels were 60% higher in the KD group and cAMP response element binding protein was 2.5-fold higher, suggesting increased sympathetic system activity. These results demonstrate that a KD can also increase BAT mitochondrial size and protein levels.