In a previous study, we revealed that mice with global AC3 knockout (AC3−/−) showed hyperphagia‐induced obesity.[7] Conversely, an AC3 gain‐of‐function mutation protects mice from diet‐induced obesity.[8] These results strongly suggest that AC3 is crucial for body weight maintenance. Here, ADCY3 is linked to obesity due to melanocortin 4 receptor deficiency.