The obesity–hypertension link is a complex, multifactorial condition that seems to involve insulin resistance, hyperactivation of the sympathetic nervous system, the renin–angiotensin system, abnormal renal sodium retention, possible leptin resistance, altered vascular reactivity, and changes in the hypothalamic–pituitary–adrenal axis. This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.