It was thought that vitamin D deficiency caused obesity, and is proposed that hypothalamus diagnoses low calcidiol concentrations in circulation and induces higher body set point by increase in appetite and decrease in energy consumption via stimulating Agouti Related Protein/Neuropeptide Y (AgRP/NPY) and suppressing pro-Opiomelanocortin/Cocaine- Amphetamine- Regulated Transcription (POMC/CART) pathway [15,16]. The gene discussed is NPY; the disease is obesity due to melanocortin 4 receptor deficiency.