Abstract
What we eat and how much of it we do are decisions controlled by an interacting system comprising the brain, the digestive tract, peripheral sensory organs and the body's fat stores (adipose tissue). This entire system is orchestrated in large part by tiny clusters of neurons at the base of our brain, specifically in the hypothalamus. These neurons are influenced by blood glucose levels and by circulating peptides that originate in the gut and the body's fat stores. Hypothalamic neurons control appetite and satiety – how much we eat and why we stop eating. These same neurons receive signals from other brain centres, such as the hippocampus, frontal cortex and amygdala that are involved in less direct influences on appetite, such as learning and memory. Input to the hypothalmus from the frontal lobe, amygdala, and other regions also provides information about what foods do or do not provide pleasure and comfort and what foods we recall make us nauseous. Finally, the hypothalamic feeding and satiety centres receive information from peripheral sensory organs, including visual, somatosensory, olfactory and, most importantly for this brief review, gustatory receptor cells. A normal, smoothly-operating system with appropriate positive and negative feedback maintains body weight and balances caloric intake with the energy requirements of our body. If the system spins out of control or is otherwise malfunctioning, eating disorders or obesity may result.