Dietary assessment methods

Selection of methods

There are several dietary assessment methods available, which have different strengths and weaknesses. The research question determines which dietary assessment method is the most appropriate. In the Dietary Research group at the Department of Nutrition at the University of Oslo, we develop, validate and use different dietary assessment methods. A brief description of the three most used methods based on self-reported data are found below.

24-hour recall (24HR)

A 24-hour recall is designed to capture a detailed report on respondents’ dietary intake over the last 24 hours. Typically, it is set up as an interview, in which participants report everything they drank or ate the previous day. The amount is specified in household measurements (e.g. spoons, cups) or by using images of different portion sizes. The 24HR is an open method that enables insights into details like food preparation methods, fat quality or bread types and meal patterns. The interviews can be set up to capture contextual data, e.g. where and with whom a meal was consumed.

A single 24HR can provide data on the mean dietary intake of a group. Due to the large day-to-day variation in dietary intake, at least two non-consecutive 24HRs are needed to estimate the usual dietary intake distribution in a group or to study the relationship between diet and health.

The European Food Safety Authority (EFSA) wishes to harmonize food consumption data from all European Union Member States by the year 2020 and recommended repeated 24HR as the preferred method for adults1. The 24HR has long been used in the large US National Health and Nutrition Examination Survey NHANES2. Austria, France, Finland, Germany, Greece, the Netherlands, Belgium, Portugal and Spain are other examples of countries that have used 24-hour diet interviews for national dietary surveys. The 24HRs should ideally be combined with a Food Propensity Questionnaire (FPQ), which is a short questionnaire in which respondents report their usual consumption of foods, specified by frequency, but not the amount.

In the latest dietary survey in Norway among adults (Norkost 3)3, the ‘Interview-assisted and computer-based 24-hour multiple-pass recall module’ of KBS, from the Department of Nutrition, University of Oslo was used to collect two non-consecutive 24HRs from each respondent over the phone. The recall module is set up to be used in a three-step sequence, resembling the approach of the United States Department of Agriculture’s Automated Multiple-Pass Method2. Image-series were available for the respondents to ease portion size estimations. A detailed description of the recall module is found elsewhere 4-5.


  1. European Food Safety Authority. Guidance on the EU Menu methodology. EFSA Journal 2014;12(12):3944
  2. Raper N, Perloff B, Ingwersen L, Steinfeldt L, Anand J. An overview of USDA's Dietary Intake Data System. Journal of Food Composition and Analysis 2004;17:545-555.
  3. Norwegian Directorate of Health. NORKOST National Food Consumption Survey 2010-2011
  4. Myhre JB, et al. Eating location is associated with the nutritional quality of the diet in Norwegian adults. Public Health Nutr. 2014 Apr;17(4):915-23. doi: 10.1017/S1368980013000268. Epub 2013 Mar 12.
  5. Medin AC. Web-based dietary assessment in Norway: New methods and their validity. Doctoral thesis. 2018. Department of Nutrition, University of Oslo, Oslo.

Food records/food diaries (FR)

A food record (FR) or a food diary is a log in which everything consumed by the respondent is entered during the course of the day or at the end of the day. It is an open method and data on e.g. food preparation, brand types and meal patterns are obtainable in addition to contextual data. Portion sizes are either measured (e.g. weighed) or estimated (e.g. using images). If recordings are done immediately after all eating occasions, the FR can be regarded as independent of memory, but they can lead to reactivity (altered dietary behavior). Children are often not able to recall their dietary intake and need assistance during recording. FRs are therefore often the method of choice in this age group.

A single FR day can be used to estimate mean intakes in a group. By collecting several record days, estimates of usual intake distributions can be obtained, and the relationship between diet and health can be studied. Ideally, one should collect non-consecutive record days over multiple time-periods.

Two different food records are currently in use in our research group:

The web-based food record/recall system (WebFR)

The WebFR was developed for use among children and adolescents in Ungkost 31. It is based on a pre-set meal structure, and images are used to estimate portion sizes. It contains around 550 items, but is regarded as an open method, as it is possible to enter information regarding any food or beverage consumed, not listed in the WebFR. The WebFR is based on the Danish Web-based Dietary Assessment Software for Children (WebDASC)2.

An interactive, voice-assisted cartoon character guides the users through each day's eating occasions, chronologically, aided by both audio and text in speech bubbles. Participants enter the foods and beverages they have consumed for each eating event separately. There are three alternative approaches. Participants can either use a search function, select items from a drop-down list, organised by categories, or use the option for open field entries. Images are used for portion size estimations. Pop-up elements are incorporated to remind the participants to enter in-between snacks, supplements, or other items often omitted from reports.

The WebFR has been validated in both 9-year-olds and 13-year-olds3-5.


  1. Norwegian Institute of Public Health. UNGKOST 3. National Food Consumption Survey 2015-2016.  
  2. Biltoft-Jensen A. et al. WebDASC: a web-based dietary assessment software for 8-11-year-old Danish children. J Hum Nutr Diet. 2014 Jan;27 Suppl 1:43-53. doi: 10.1111/j.1365-277X.2012.01257.x.
  3. Medin AC, Astrup H, Kåsin BM, Andersen LF. Evaluation of a Web-Based Food Record for Children Using Direct Unobtrusive Lunch Observations: A Validation Study. J Med Internet Res 2015;17(12):e273.
  4. Medin AC, Carlsen MH, Andersen LF. Associations between reported intakes of carotenoid-rich foods and concentrations of carotenoids in plasma: a validation study of a web-based food recall for children and adolescents. Public Health Nutr. 2016 Jun 27:1-11.
  5. Medin AC, Hansen BH, Astrup H, Ekelund U, Andersen LF. Validation of energy intake from a web-based food recall for children and adolescents. PLoS One. 2017 Jun 8;12(6):e0178921

The pre-coded food diary (PFD)

The pre-coded scannable food diary (PFD) was developed in 1999 and 2000 for use among children and adolescents in the UNGKOST-20001, but has later been modified for use among adults. 

The diary consists of 20 pages of lists of foods and beverages. The lists are divided into food categories. The PFD is regarded as an open method, as there are empty lines in each food category enabling entering of foods or beverages not listed. Each recording day is divided into five time periods. Respondents indicate the consumed portion size of each food item by entering the number of units in household measures (e.g. spoons, cups), or by using images for portion size. Approx. 25% of food- or beverage-items have images for portion size estimation.

The PFD has been validated in different groups: in 9-year-old children2,3 in 13-year-olds4, in adults5,6, and in women diagnosed with breast cancer7. The images from the photographic booklet used along the PFD have also been validated in 9-19 year-olds of both sexes8.


  1. Norwegian Directorate of Health. UNGKOST-2000. National Food Consumption Survey 2000. 
  2. Lillegaard IT, Andersen LF. Validation of a pre-coded food diary with energy expenditure, comparison of under-reporters v. acceptable reporters. Br J Nutr. 2005 Dec;94(6):998-1003.
  3. Lillegaard IT, Løken EB, Andersen LF. Relative validation of a pre-coded food diary among children, under-reporting varies with reporting day and time of the day. Eur J Clin Nutr. 2007 Jan;61(1):61-8. Epub 2006 Jul 19.
  4. Andersen LF et al. Validation of a pre-coded food diary used among 13-year-olds: comparison of energy intake with energy expenditure. Public Health Nutr. 2005 Dec;8(8):1315-21.
  5. Stea TH. Et al. Validation of a pre-coded food diary used among 60-80 year old men: comparison of self-reported energy intake with objectively recorded energy expenditure. PLoS One. 2014 Jul 14;9(7):e102029. doi: 10.1371/journal.pone.0102029. eCollection 2014.
  6. Myhre JB, et al. Relative validation of a pre-coded food diary in a group of Norwegian adults - Comparison of underreporters and acceptable reporters. PLoS One. 2018 Aug 30;13(8):e0202907. doi: 10.1371/journal.pone.0202907. eCollection 2018.
  7. Brunvoll SH, et al. Validation of repeated self-reported n-3 PUFA intake using serum phospholipid fatty acids as a biomarker in breast cancer patients during treatment. Nutr J. 2018 Oct 17;17(1):94. doi: 10.1186/s12937-018-0402-6.
  8. Lillegaard IT, Øverby NC, Andersen LF. Can children and adolescents use photographs of food to estimate portion sizes? Eur J Clin Nutr.2005 Apr;59(4):611-7. 

Food Frequency Questionnaires (FFQ)

An FFQ is designed to capture the usual consumption of foods and beverages, using a fixed list of foods and beverages, specified by frequency and often the amount. It covers a defined period, usually the last 1-12 months. It may have images as an aid for portion size estimation.

FFQs provide data on the habitual (usual) dietary intake. They may cover parts of the diet or the total diet, depending on types and number of items included in them. FFQs are commonly used in studies looking at the association between diet and health. FFQs (and short versions of FFQs) can in a feasible way capture dietary intake retrospectively.

Two different food frequency questionnaires are currently in use in our research group:

Web-based food frequency questionnaire (WebFFQ)

The WebFFQ was developed in collaboration with the University Center for Information Technology at the University of Oslo. It is a self-administered web-based FFQ, set up to capture the habitual total dietary intake in adults. It contains about 280 foods or beverages, with images, in addition to household measures, illustrating different portions sizes to help the portion size estimation. The WebFFQ also has skip-algorithms and inherent error checks.

The WebFFQ has been validated in adults1.


  1. Medin AC  et al. The validity of a web-based FFQ assessed by doubly labelled water and multiple 24-h recalls. Br J Nutr. 2017 Dec;118(12):1106-1117. doi: 10.1017/S0007114517003178. Epub 2017 Dec 5.

Scannable paper-based food frequency questionnaire (FFQ)

The FFQ is paper-based, scannable and designed to be self-administered method assessing the habitual total dietary intake in adults. It includes 256 questions about foods or beverages. Portion sizes are estimated by using household measures (e.g. spoons, deciliter, slices).   

The FFQ has been validated in several different groups of adults1-5.


  1. Andersen LF et al. Evaluation of a food frequency questionnaire with weighed records, fatty acids, and alpha-tocopherol in adipose tissue and serum. Am J Epidemiol. 1999;150:75–87.
  2. Andersen LF et al. Validation of energy intake estimated from a food frequency questionnaire: a doubly labelled water study. Eur J Clin Nutr. 2003;57:279–84.
  3. Nes M et al. Accuracy of a quantitative food frequency questionnaire applied in elderly Norwegian women. Eur J Clin Nutr. 1992;46:809–21.
  4. Andersen LF, Solvoll K, Drevon CA. Very-long-chain n-3 fatty acids as biomarkers for intake of fish and n-3 fatty acid concentrates. Am J Clin Nutr. 1996;64:305–11.
  5. Brunvoll SH, et al. Validation of repeated self-reported n-3 PUFA intake using serum phospholipid fatty acids as a biomarker in breast cancer patients during treatment. Nutr J. 2018 Oct 17;17(1):94. doi: 10.1186/s12937-018-0402-6.



Published Aug. 20, 2012 11:28 AM - Last modified Oct. 22, 2019 2:36 PM