This involves weighing all the ingredients used in the preparation of dishes, the inedible wastage, the cooked weight of the individual's portion and the plate waste. Nutrient intakes can then be determined by chemical analysis of aliquot samples. The method requires a great deal of subject co-operation and is therefore difficult to apply to a representative sample of the population. Also, because of the amount of supervision necessary and the degree of interference in the home, subjects may eat differently during the survey period. These factors, coupled with the expense of the method make it of limited applicability in population surveys.