Background Food Photographs and standard portion sizes have been used with adults to assess portion size when recording dietary intake. The effectiveness of these methods may be reduced when memory/recall is required and children may have problems using these techniques.
Methods Adults (47) and children (37) were recruited from amongst university personnel, their children and children's friends to assess portion sizes of nine self-served amounts of selected food items using food photographs and standard descriptions of portion sizes. Portion sizes were estimated directly after self-serving and three – 4 days later.
Results Substantial differences in the estimate of portion sizes were observed for most foods regardless of the method used or the age of the subjects, median difference range: −52–100%. For children there were greater errors using both methods than for adults. Significant differences were found between the two methods of estimating weight. The food atlas provided higher median estimated weights for the majority of the food items. There were very few differences in the estimation of portion sizes between the two testing periods.
Conclusion The findings would suggest that either an alternative method or a modification of the methods used here for estimating portion sizes in young subjects, for example standard food portion sizes for children of different ages such as those that are being developed by the Food Standards Agency, would be more appropriate.