The selfish brain: Competition for energy resources.

Obesity and type 2 diabetes have become the major health problems in many industrialized countries. Here, I present the unconventional concept that a healthy organism maintains its systemic homeostasis by a "competent brain-pull", i.e., the brain's ability to properly demand glucose from the body, and that the underlying cause of obesity is "incompetent brain-pull." I describe the energy fluxes from the environment, through the body, toward the brain as the final consumer in a "supply chain" model. There is data-based support for the hypothesis, which states that under conditions of food abundance incompetent brain-pull will lead to build ups in the supply chain culminating in obesity and type 2 diabetes. There is also support for the related hypothesis, which states that under conditions of food deprivation, a competent brain-pull mechanism is indispensable for the continuation of the brain's high energy level. To experimentally determine how the competent brain-pull functions to demand for cerebral energy, healthy young men undergoing psychosocial stress were studied. It was found that the brain under stressful conditions demands for energy from the body by using a brain-pull mechanism, which is referred to as "cerebral insulin suppression" and in so doing it can satisfy its excessive needs during stress. This article gives an overview about the recent work on the "Selfish Brain" theory dealing with the maintenance of the cerebral and peripheral energy homeostasis.