Up to one third of dementia sufferers eat an increased quantity of food compared with their premorbid intake, at some stage during the dementia. In addition, over half of people with dementia are reported, by their carers, to show a marked change in food choice, particularly an increased liking for sweet food. The macronutrient content of foods chosen and the ratio of sweet to savoury foods were investigated experimentally using a standardized mixed meal. Three subject groups were studied: 17 people with dementia who were reported by their carers to overeat and who ate excessively under experimental conditions; 14 people with dementia who ate a normal amount; and, normal, non-demented controls (18 under 50 years old and 14 over 50 years old). The results showed that the normal elderly people chose a lower proportion of high-protein food than the young. The proportion of protein eaten was lower in people with dementia than in age-matched controls and was even lower in the hyperphagic dementia group. The proportion of sweet food eaten was higher in people with dementia and even higher in people with dementia who were hyperphagic. Various mechanisms to account for the results are discussed.