• Indication
• Pros and cons
• Practical considerations
• Resources required
• References
• Examples and links

• Dietary assessment
• Methods
• Weighed food diary
• Indication

Indication

The method provides rich and detailed dietary data on current intake at an individual level.  If sufficient days are recorded, day-to-day variation can be studied. The method is expensive and resource intensive and imposes a substantial individual burden on the participant which means that it is not practical for large population studies.  The UK switched to using an unweighed or estimated food diary in the current National Diet and Nutrition Survey rolling programme due to a perception that the weighed method was reducing response rates and interfering with the completeness of the records (NDNS). Analysis of data from the UK adult National Diet & Nutrition Survey from 2000-01 showed high levels of underreporting (Rennie et al, 2005).  Weighed food diaries have been used considerably less frequently in recent years.

Weighed food diaries are suitable for small intervention or metabolic studies. As they measure current intake, they cannot be used in studies looking at associations of past diet with health outcomes. The method has also been used in calibration studies of other less involved and less expensive methods. There is evidence however that record (or recall) methods of dietary assessment do not satisfy the independence criteria which is a pre-requisite to validation studies i.e. there is a risk of correlated error (Day et al, 2001). Weighed records remain invaluable for estimations of actual portion sizes, which are needed for estimated methods.

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