The EPIC-Norfolk uses a seven day diary as the primary dietary record used in EPIC-Norfolk. Diaries are issued as A5, 45-page booklets. Participants record everything that they have eaten for seven days (preferably 7 consecutive days covering weekdays and weekend days) with particular attention to amounts and how foods are prepared. The pages for each day have eight sections, seven meal slots for recording food and drinks taken from before breakfast to last thing and even during the night, and a checklist and section for recording additional snacks and other information.

The front pages of the diary include suggestions for describing and quantifying food and drinks consumed. Participants are encouraged to include full information including how foods are cooked, the type of fat or oil used in preparation or frying, brand names of commercial products and details of recipes used. The amount an individual consumes of each food item or beverage is crucial information and detailed information is also available on how different foods may be usefully quantified.

There are seventeen sets of colour photographs (nineteen in version 3 of the diary used in the third health check 2009) showing different portions of a range of different foods. Participants can use these where appropriate to help them quantify foods. 

The diary can be used with any data-entry program, and was used with the Data Into Nutrients for Epidemiological Research (DINER) software in EPIC-Norfolk.