WHAT DID I EAT YESTERDAY - DETERMINANTS OF ACCURACY IN 24-HOUR FOOD MEMORIES

Large-scale diet-related epidemiological work relies on the quality of self-reported food consumption. As this epidemiological work forms the basis of knowledge of the relationship of diet to disease, it is essential that the self-reports of personal diet are understood. It is generally accepted that foods consumed are under-reported, even over as short a period as 24 hours. However, little is known about the potential systematic biases that may affect the quality of self-reported food intake. The current study examines the accuracy of memories of the consumption of snack foods eaten in the previous 24 hours and investigates factors that may bias these memories. All participants had previously participated in a randomized intervention trial to lower dietary fat intake to 20 per cent of calories. Fifty-six women (intervention and control) tasted eight snack foods in a laboratory setting. They were telephoned a day later and asked to recall the type of snack foods (M&Ms, pretzels, etc.) and the quantity of each food they consumed. Subjects in general under-reported the number of selections and the quantity of each item consumed. Women who accurately recalled an item, reported more liking for that item compared to those who forgot the item. Women currently maintaining a low-fat diet were less accurate in their recall of low-fat items than women on a high-fat diet. Low-fat eaters, however, may be slightly better at recalling how much of certain foods they consumed. Results have implications for survey research and understanding the psychological influences on reports of food consumption used in large-scale diet studies.