However, results from fMRI studies investigating correlations of the postprandial decrease in endogenous plasma ghrelin with food cue reactivity in brain regions involved in reward, motivation and emotion have been inconsistent, likely related to often small samples sizes, differences in study design and obesity status, and specificity of ghrelin immunoassays to AG, DAG, or both [56, 59‐68). This evidence concerns the gene GHRL and obesity due to melanocortin 4 receptor deficiency.