With increasing fat mass, peripheral vascular resistance actually decreases because, surprisingly, blood flow to adipose tissue is quite high in comparison to that to skeletal muscle. Thus the increased capillary bed in an expanded adipose tissue mass reduces total vascular resistance. Blood pressure nevertheless rises with increasing weight because cardiac output increases in parallel, probably as the result of sympathetic nervous system activation and increases in blood volume. Thus one could speculate that the increased cardiovascular risk of hypertension is not so much to do with elevated blood pressure itself but is the consequence of the increased peripheral vascular resistance, caused by resistance vessel wall hypertrophy, or by vasoconstriction.