INS and Obesity: Centrally, disruption of insulin receptors in the hypothalamus causes obesity, insulin resistance, hyperphagia, and hyperleptinemia in mice (32) and when insulin was injected into the cerebral ventricles of baboons in a study over 40 years ago, food intake and endogenous glucose production were both suppressed (9) underpinning the central role of insulin in energy homeostasis.