24-hour dietary recalls

The method assesses food and beverage consumption during the previous day or the preceding 24 hours. The variety of outcomes assessed by the 24-hour dietary recall method is shown in Table 9.1.

To capture habitual consumption of foods, multiple recalls are essential. The more days of recall, the better capture of between-day variability, seasonal variability, and foods episodically consumed. In a preliminary study to decide the method for the UK Low Income Diet and Nutrition Survey (LIDNS), four repeat 24-hour recalls were recommended as the most appropriate method of dietary assessment [1]. In an Australian study in adults, eight repeat 24-hour recalls were recommended to capture the variation in macronutrient intake [2]. The number of recalls needed to assess individuals’ exposure to nutrient intake can be statistically calculated, ranging from 3 days for major macronutrients to weeks for micronutrients.

By contrast, if the research aim is to identify average consumption in a population, a single 24-hour recall for individuals from a target population is sufficient. However, to identify population-level statistics of variations and prevalence of individuals meeting certain consumption levels (recommended levels of intakes), multiple 24-hour recalls are necessary.

Table D.9.1 Dietary outcomes assessed by multiple 24-hour dietary recalls.

Dietary dimension Possible to assess?
Energy and nutrient intake of total diet Yes
Intake of specific nutrients or food Yes
Infrequently consumed foods Maybe
Dietary pattern Yes
Habitual diet Yes
Within-individual comparison Yes*
Between-individual comparison Yes
Meal composition Yes
Frequency of eating/meal occasions Yes *
Eating environment Yes
Adult report of diet at a younger age No

* possible when repeated measures were collected over time.


The 24-hour dietary recall is a retrospective assessment method carried out by a trained interviewer. This method can also be self-administered i.e. with no interviewer. The 24-hour recall is normally undertaken in chronological order of consumption (i.e. from morning to night). The multiple pass approach has been often used as described below.

Multiple-pass approach

The multiple-pass recall is a staged approach to the dietary recall thought to be more tailored to human cognition than the chronological approach. The multiple-pass method has been widely used in national surveys and research [3]. The following is an example of the 5-step approach. The exact stages or passes may vary between protocols.

  1. Quick list, to collect a list of foods and beverages consumed during the previous day (i.e. over the past 24 hours)
  2. Forgotten foods, to probe for foods forgotten during the quick list
  3. Time and occasion, to record time and eating occasion for each food
  4. Detail cycle, to record detailed description, amount, use of condiments, cooking methods, brands of foods if purchased, and other information as a review of the 24-hour day
  5. Final probe, to probe for anything else consumed

An example of a 24-hour dietary recall entry sheet used by an interviewer is displayed in Figure D.9.1. Note that entry can include “food code”, which can later facilitate data entry.

Figure D.9.1 Example of 24-hour dietary recall entry sheets.
Source: King's College London.

Ideally, on the day previous to the 24-hour recall assessment, the respondent needs to be uninformed about its implementation, so that dietary behaviour is not affected. For example, in the US national survey [4], two 24-hour recalls are conducted. The first one is through a face-to-face interview and the second one is conducted by an assessor over the phone. The respondent is informed that a phone contact is attempted approximately two weeks after the first 24-hour recall, but not informed which day is selected to avoid a respondent changing his/her dietary habit.

In an interview, aids to recall occasions during the previous day can be provided, including information on the weather, local news, local events, etc. It is also useful to undertake a short questionnaire to supplement the recall data. The questionnaire may ask about the type of staple foods usually used, e.g. bread, milk, margarine, and breakfast cereal, to save time recording this information each time it appears in the recall.

As a part of the 5-step approach, a participant should be guided to recall dietary items often forgotten. Such items include ingredients used in cooking and during consumption, snacks between mealtimes, and dietary supplements. A participant should also be guided to answer whether the day they reported was a usual day, and whether they follow a special diet or not (e.g. vegetarian diet, dieting to lose/gain weight, for a disease, or for lactose intolerance).

Whether foods were purchased outside or cooked at home, brands of purchased foods, and how much money was spent may also be answered. What variables are to be captured in the 24-hour assessment should be confirmed before its implementation.

Time interval between multiple recalls

The time interval(s) between multiple 24-hour recalls should be considered depending on the purpose of the study. If the purpose of the study includes the habitual intake over a year, then 24-hour recalls should be administered across all seasons within the year to account for seasonal variation. In some cases, it is considered useful to use a hybrid between a 24-hour recall and a food frequency questionnaire. The hybrid (see section below for examples) covers the intake over the previous day but includes questions of specific food items with frequencies (usually semi-quantitative). These tools are especially useful in large-scale studies where the use of interviewers is not practical but a higher amount of precision is desired compared to classical FFQ.

Interview mode

The interview can be carried out in person, by telephone, or online via the Internet. In the Norwegian arm of the EPIC study, no significant differences in the dietary data obtained were found when face-to-face 24-hour recalls were compared to telephone 24-hour recalls [5].

Computer-based 24-hour recall, including those carried out online, has the following advantages:

  1. Standardises recalling steps
  2. Show typical serving sizes of foods by displaying photos
  3. Records brands and specific foods by showing photos
  4. Enters data into an electronic format for further processing

Examples of this approach include INTAKE24 and Oxford WebQ, as described in Technology Assisted Dietary Assessment.

Estimation of portion size

The estimation of portion size in the 24-hour recall usually requires the use of aids such as:

  1. Food photographs
  2. Household measures
  3. Two-dimensional grid
  4. Food models

If none of these methods applies to a certain food item that a participant consumed, the participant might refer to the size of the item (e.g. small, medium, or large) and then depending on the specific item, the size can be converted to an approximation of the weight.

  1. Recalls are suitable for nutritional surveys and intervention studies and could be used in prospective cohort studies
  2. Useful for studies requiring a measure of average levels of dietary consumption in a given population
  3. Several national surveys use the 24-hour recall method because of its high response rate and its ability to obtain detailed information. For example, in the United States, an interviewer administered automated multiple pass recall (AMPR) is the dietary assessment method used in national surveys
  4. Often used as a reference method to assess the validity of other methods, including food-frequency questionnaires and diet history
  5. Often used as a measure of adherence to a dietary intervention, coupled with a short dietary checklist or a questionnaire

As a 24-hour recall has an open-ended format, outcomes from 24-hour recalls can be diverse, including consumption of specific food groups, cooking at home, eating meals with family members or alone, use of table salt, use of dietary supplements, and whether a respondent consumed breakfast, takeaway foods or snacks between meals.

Estimates of nutrient intakes follow a general procedure that is common with food records and food-frequency questionnaires. The following steps to estimate nutrient intakes are undertaken:

  1. Disaggregate records of mixed meals quantitatively to individual foods and ingredients (if a food composition table has a mixed meal which is comparable to that in the recall’s output, disaggregation is not necessary)
  2. Convert portion size to gram amounts or amounts in a standard unit (ml for liquids) of each dietary consumption
  3. Match all foods and ingredients with items in a food composition table
  4. Obtain nutrient intakes from each food, by calculating a product of an amount of each item consumed and nutrients contents per amount of each item
  5. Obtain nutrient intakes per day per individual by calculating a sum of intakes of the nutrient per day per individual. This calculation can be specific to intakes in breakfast or different settings in a day.

Nutrition experts may ask the question, “How much of vitamin A intake come from vegetable consumption in the population?” This can be easily calculated as the ratio of the total vitamin A intake from vegetables across all individuals to the total vitamin A intake from all foods across all individuals. This calculation is important to identify major food sources for a particular nutrient in a population.

Key characteristics of single and multiple 24-hour recall are described in Table D.9.2.


  1. Theoretically unlimited level of specificity for the foods consumed
  2. Respondent burden is relatively low
  3. Procedure does not alter food intake patterns
  4. If interviewer-administered, literacy not required
  5. Interview relatively quick (e.g. 20-30 minutes)
  6. Sensitive to ethnic differences


  1. Method dependent on respondent’s ability to recall intake accurately
  2. Possibility of recall bias where the individual may selectively recall food items, as with all self-report methods
  3. Expensive to administer due to high interviewer burden, but can be conducted via telephone or online to reduce cost
  4. It can be resource-intensive, for example, if paper-based 24-hour recalls are implemented and those require a large volume of data entry, data cleaning, re-contacting the respondents, and data processing
  5. Repeats of 24-hour diet recalls further increase the time and cost of data processing
  6. The process of coding and conversion of data to nutrients is time-consuming and labour-intensive, requiring trained diet coders and a nutrient database and analysis program

Table D.9.2 Characteristics of 24-hour dietary recall.

Characteristic Single recall Multiple recall
Number of participants Up to ~5000 Up to ~1000
Cost of development Low Low
Cost of use Medium High
Participant burden Low very High
Researcher burden of data collection High High
Researcher burden of coding and data analysis Medium High
Risk of reactivity bias No No
Risk of recall bias Yes Yes
Risk of social desirability bias Yes Yes
Risk of observer bias Yes Yes
Participant literacy required Maybe Maybe
Suitable for use in free living Yes Yes
Requires individual portion size estimation Yes Yes

Considerations relating to the use of 24-hour dietary recall for assessing diet in specific populations are described in Table D.9.3.

The use of 24-hour recalls is particularly challenging in young children and the elderly. The ability of a child to provide a dietary recall increases markedly after the age of 8 years [6], while the ability of younger children appears variable [7]. For these reasons, in 24-hour recalls of diets of children and especially of younger children, their parents or caregivers are invited to assist the dietary reporting.

The use of prompts in small numbers of children aged 10 years has been investigated. Specific prompts were found to hinder recall compared to free recall [8]; an open interview format was preferable to a meal interview format [9]. It is not clear what order of recall, i.e. reverse order versus forward order, is preferable to use in children [9]. Recency was found to have a positive effect on children’s recall, which may mean it is preferable to inquire about intake during the previous 24 hours rather than the previous day [10].

One study in UK pre-schoolers has shown that repeat (x3 days) automated multiple pass recall (AMPR) is not valid at an individual level to measure energy intake when compared to energy expenditure using doubly labelled water; over-reporting was apparent [11]. A similar study was repeated in young school children and although inaccuracies were reduced, intakes were still only valid at a group level [11]. This concurred with an earlier US study in young children [12]. These studies all relied on proxy-reporters, like parents and carers.

Table D.9.3 Diet assessment by 24-hour dietary recall in different populations.

Population Comment
Pregnancy Suitable
Infancy and lactation Requires proxy
Toddlers and young children Requires proxy
Adolescents Suitable
Adults Suitable
Older Adults May require proxy depending on cognitive function
Ethnic groups Requires language/cultural specificity

Dietary recalls require a trained interviewer to undertake the dietary assessment in person or via telephone. The training of the interviewer is of utmost importance to ensure that the dietary data acquired is as reliable and valid as possible:

  1. Interviewers should have knowledge of local foods (or be provided with relevant background documents); this is particularly important when working with ethnically diverse populations
  2. It is also important at a regional level that colloquial names for food and eating occasions are readily understood
  3. It is useful for the interviewer to be familiar with the food coding system to be used
  4. Coding of previously collected 24-hour recalls should be included as part of the training as this helps the interviewer to understand the questions to ask about specific foods
  5. The interviewer must have good inter-personnel skills and should remain non-judgemental in both verbal and non-verbal cues throughout the interview
  6. Questions must not lead or be directive, and judicial use of probing questions must be made
  7. Regular reviews of the quality of the data collected (ideally by those responsible for coding the 24-hour recalls) allows feedback to be given to the interviewers and helps maintain the quality of data collected
  8. A standard operating procedure of interviewing is required to reduce the likelihood of interviewer-induced bias
  9. A checklist of prompts is useful for the interviewer e.g. for commonly forgotten foods and items eaten in combination
  10. 24-hour recalls via phone and face-to-face interview can be improved by physically sending photo books and cooking utensils, and by communicating with a computer as mentioned above
  1. Trained interviewer
  2. Checklist and materials to record responses
  3. Trained diet coders
  4. Nutrient database and analysis program
  5. Portion estimation aid

A method specific instrument library is being developed for this section. In the meantime, please refer to the overall instrument library page by clicking here to open in a new page.

As mentioned above and introduced in Technology Assisted Dietary Assessment, computer-based 24-hour recall has been developed in recent years (as of 2020). The advantages include the following:

  1. Display of portion sizes
  2. Display of often forgotten foods or condiments associated with each food item or meals consumed. The multiple-pass approach includes the step to list often forgotten foods, but not for each food item or meal consumed. Facilitating recall of anything associated with each food is a unique strength.
  3. Boost data entry and estimation of nutrient intakes. As 24-hour recall has an open-ended format, data entry can be highly time-consuming. However, computer-based recall can largely reduce this concern if data are directly entered.

As this example of the advancement of the computer-based 24-hour recall method, its development is about a system and an algorithm to facilitate recalls and data entry.

  1. Holmes B, Dick K, Nelson M. A comparison of four dietary assessment methods in materially deprived households in England. Public Health Nutr. 2008;11(5):444-56.
  2. Jackson KA, Byrne NM, Magarey AM, Hills AP. Minimizing random error in dietary intakes assessed by 24-h recall, in overweight and obese adults. Eur J Clin Nutr. 2008;62(4):537-43.
  3. Moshfegh AJ, Rhodes DG, Baer DJ, Murayi T, Clemens JC, Rumpler WV, et al. The US Department of Agriculture Automated Multiple-Pass Method reduces bias in the collection of energy intakes. Am J Clin Nutr. 2008;88(2):324-32.
  4. Ahluwalia N, Dwyer J, Terry A, Moshfegh A, Johnson C. Update on NHANES Dietary Data: Focus on Collection, Release, Analytical Considerations, and Uses to Inform Public Policy. Adv Nutr. 2016;7(1):121-34.
  5. Brustad M, Skeie G, Braaten T, Slimani N, Lund E. Comparison of telephone vs face-to-face interviews in the assessment of dietary intake by the 24 h recall EPIC SOFT program--the Norwegian calibration study. Eur J Clin Nutr. 2003;57(1):107-13.
  6. Livingstone MB, Robson PJ. Measurement of dietary intake in children. Proc Nutr Soc. 2000;59(2):279-93.
  7. Warren JM, Henry CJ, Livingstone MB, Lightowler HJ, Bradshaw SM, Perwaiz S. How well do children aged 5-7 years recall food eaten at school lunch? Public Health Nutr. 2003;6(1):41-7.
  8. Baxter SD, Thompson WO, Davis HC. Prompting methods affect the accuracy of children's school lunch recalls. J Am Diet Assoc. 2000;100(8):911-8.
  9. Baxter SD, Smith AF, Guinn CH, Thompson WO, Litaker MS, Baglio ML, et al. Interview format influences the accuracy of children's dietary recalls validated with observations. Nutr Res. 2003;23(11):1537-46.
  10. Baxter SD, Smith AF, Litaker MS, Guinn CH, Shaffer NM, Baglio ML, et al. Recency affects reporting accuracy of children's dietary recalls. Ann Epidemiol. 2004;14(6):385-90.
  11. Reilly JJ, Montgomery C, Jackson D, MacRitchie J, Armstrong J. Energy intake by multiple pass 24 h recall and total energy expenditure: a comparison in a representative sample of 3-4-year-olds. Br J Nutr. 2001;86(5):601-5.
  12. Johnson RK, Driscoll P, Goran MI. Comparison of multiple-pass 24-hour recall estimates of energy intake with total energy expenditure determined by the doubly labeled water method in young children. J Am Diet Assoc. 1996;96(11):1140-4.