Why should we study human food intake behaviour?

Several aspects of human eating behaviour may be relevant for identifying effective measures to treat or prevent diseases like obesity, diabetes, or the metabolic syndrome, whose natural history is strongly influenced by nutritional factors. Physiological factors determine hunger, satiety and satiation, and a biological learning mechanism supports the acquisition of food likes and dislikes. The paradigm of "conditioned taste aversion" refers to the acquisition of a strong rejection response after the intake of a food has been followed by digestive disorder. Food likes are acquired following the experience of the beneficial post-ingestive effects of intake. Physiological mechanisms reinforce the liking for energy-rich foods and both environmental and biological conditions facilitate "passive overconsumption". Sensory factors are important determinants of appetite and food choices from birth to old age. The human newborn exhibits an innate repertoire of acceptance or rejection for taste substances. The progressive change of sensory functions associated with ageing affects appetite and the pleasure of eating. Many individual psychological characteristics affect food intake behaviour in a significant way. These include chronic dietary restraint, disinhibition, etc. These psychological traits can be objectively assessed using validated psychometric instruments. Various stimuli present in the environment also affect ingestive behaviours in humans. Portion size is one potent environmental determinant of how much a person eats, regardless of hunger. The general increase in portion sizes observed in North America over the last decades might have played an important role in the rapid rise of obesity prevalence. Socio-economic factors also affect food selection and food intake in human societies. Factors such as education level and income determine food choices and behaviours in a way that does affect the risk of obesity. Behavioural science has provided many insights about crucial cause-and-effect relationships that affect nutrition and health. Therefore, clinicians and nutritionists cannot neglect this important area if they wish to effectively modify the habitual diet of individual patients or the general population.