Inverse relationship between food quantity and energy density - an analysis of consumed food items in obese patients.

BACKGROUND Food energy density is an important parameter for daily energy intake. In a large cross-sectional study from the U.S. an inverse relationship was found between energy density and the quantity of consumed food items. This, however, was not demonstrated in a large spanish survey. In an intraindividual analysis of food intake of 280 obese patients we have therefore examined the relationship between energy density (ED), food quantity and energy intake. Additionally, we demonstrate the contribution of various food groups to the observed changes. METHODS Dietary protocols of 280 overweight and obese patients were analyzed and ranked intraindividually on the basis of the daily energy density. RESULTS Daily food quantity decreased by 370 g with increasing energy density paralleled by a rise of energy intake by 520 kcal. Food groups with low (≤ 1,5 kcal / g) medium (1,51-2,49 kcal / g) and high (≥ 2,5 kcal / g) ED changed differentially. Medium and high ED food was consumed more while low ED food was responsible for the reduction of food quantity. This inverse relationship was primarily due to the respective changes at lunch and dinner. Food quantity decreased by reduction of meat, fish, vegetables, fruit, carbohydrate accompaniments and soup. These are all items of a typical main meal. Conversely the increase of energy density was due to bread, cheese, sausages, fastfood and cake. During snacks increasing energy density was also associated with reduced food quantity but energy intake remained constant. Mainly responsible for this shift were fruit, yoghurt, cake, chocolate and nuts, respectively. At breakfast the rise of energy intake was directly proportional to energy density while the meal quantity remained unchanged. CONCLUSION The inverse relationship between food quantity and energy density is not due to an intentional reduction of food items with high energy density but rather the result of a shift from one meal type to another. These data support the beneficial effects of main meals consisting of meat, fish, carbohydrates, vegetables and fruit in contrast to meals with food items such a bread, cheese, fastfood and cake. A compensation of high energy density would require a reduction of food quantity down to a level where satiety is no longer guaranteed. Therefore, a change of eating habits towards a bypocaloric diet requires a reduction of food energy density.