Obesity distinctly increased plasma FGF-21 (chow ad libitum vs. HFD ad libitum; Figure 3D), which showed a trend toward higher concentrations under exposure to hypoxia than under food restriction (pmol/l: hypoxia, 44.1 ± 9.5, vs. weight matched control, 23.7 ± 3.6; p = 0.058; Figure 3D). The gene discussed is FGF21; the disease is obesity due to melanocortin 4 receptor deficiency.