INS and obesity due to melanocortin 4 receptor deficiency: Likewise, Nascimento-Sales et al. (2017), found that while C57BL/6N mice develop obesity more quickly than FVB/N mice, FVB/N mice actually show a significantly greater degree of metabolic intolerance after treatment with a HFD as evidenced by higher insulin resistance, greater liver steatosis, and a large degree of epididymal white adipose tissue induced inflammation.