GHR and obesity due to melanocortin 4 receptor deficiency: Furthermore, the relatively elevated GHBP levels in FL fish after 1-week fasting, concomitant with low plasma GH levels, suggest that the GH-endocrinology has been altered during the genetic selection for high muscle adiposity, and the FL fish may represent an “obesity” phenotype (37), similar as seen in obese humans with low GH and high GHBP plasma levels (61, 62).