The Concept of CMR

Determinants of Energy Intake

Food intake is controlled by a number of biological and external factors/stimuli. External factors that regulate appetite (and food intake) include cultural and psychological influences such as economic background, education, learned experiences, cognitive effects, portion size, and, especially, food palatability (Figure) (1). Given that a variety of outside influences affect one’s eating habits, eating (and not eating) can be seen as a kind of behaviour in which individual and environmental factors influence the amount of energy ingested. Accordingly, hectic food patterns are known to be a significant cause of obesity in individuals with eating disorders (2). There are also many metabolic and peripheral pathways that are part of the human appetite and satiety system. This very complex system governs energy intake and expenditure and is responsible for feeding and satiety. Disturbances to this system can affect energy balance and cause weight gain (in most cases) or weight loss. Many sites are involved in the appetite system, and the brain (especially the hypothalamic region) is one of the centres where information (signals) from tissues is analyzed and “orders” (other signals) are sent to the system controlling appetite and eating. The gastro-intestinal (GI) tract, liver, pancreas, and adipose tissue therefore engage in a cross-talk between peripheral organs and the central nervous system (CNS). In response to peripheral signals, the CNS secretes numerous hypothalamic peptides (neuropeptides) that play a role in food intake and energy balance (3).