Endocannabinoids and the Non-Homeostatic Control of Appetite

Abstract

The usual physiological perspective on appetite and food intake regards control of eating simplistically, as merely the reflexive behavioural component of a strict homeostatic regulatory system. Hunger is seen to arise in response to energy deficit; meal size is determined by the passage of nutrients into the gut and the stimulation of multiple satiety signals; and overall energy intake is modified to reflect the balance of fuel reserves and energy expenditure. But everyday experience shows that we rarely eat simply through need. Rather, food stimuli exert a powerful influence over consumption through their appeal to innate and learned appetites, generating the psychological experiences of hunger, craving and delight independently of energy status. That these important and influential subjective experiences are mediated through complex neurochemical processes is self-evident; but the chemical nature of our infatuation with, and subservience to, the motivating properties of foods are overshadowed by mechanistic, peripherally anchored models that take little account of psychological factors, and which consequently struggle to explain the phenomenon of obesity. This chapter discusses recent developments that suggest the endocannabinoids are key components of the central mechanisms that give rise to the emotional and motivational experiences that lead us to eat and to overconsume.