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Strengths and Weaknesses info

Click the different types of dietary assessment tools to discover their strengths and weaknesses allowing you to compare and identify the most suitable tool for your research study. The dietary assessment tools were developed using the Delphi method. Overall 57 experts were involved in the development of the list of strengths and weaknesses of each type of DAT. To see how these were developed, please refer to the BPG paper : Best Practice Guidelines paper.

Back to Guidelines

Food Diaries

24Hr Recalls

Food Frequency Questionnaires

Food Checklists

Diet Histories

Emerging Technologies

Food Diaries

Strengths

Weaknesses
Prospective, short-term methods where details of all foods and drinks are recorded by the participant as they are consumed, usually over several days. Amount of food eaten can be either estimated using household measures (estimated food diary) or weighed by the respondent or research assistant in the home (weighed food diary). It can be long term method if carried out multiple times, i.e. over multiple phases. Also known as food records or diet records. Can be completed online (see emerging technologies section).
  • Provides detailed data on all food and drink consumption and portion size description, leading to good estimates of short term total dietary intake and total nutrient intake if completed thoroughly and nutritional supplement use is assessed.
  • Allows collection of contextual information (e.g. meal timing, location, brand, eaten with whom, TV/computer/device etc.).
  • Provides food and nutrient data that can be used in numerous types of analysis to answer a variety of research questions.
  • Potentially little reliance on memory when completed prospectively i.e. when food is consumed or soon after.
  • Weighed food diaries - weight of ingredients, final cooked weight and food waste can be measured leading to detailed information of consumption and good estimation of actual intakes of individuals.
  • Design of diary can include prompts to ensure inclusion of different eating occasions (including snacks) and pictures to help gauge portion sizes therefore enabling more comprehensive data.
  • Reasonably cheap to collect data (although traditionally coding is time-consuming and expensive).
  • Use of standardised instructions and coding rules with skilled researchers will help improve accuracy.
  • Multiple food diaries - can be used to estimate usual intakes of individuals and distributions in a group if administered over a sufficient number of non-consecutive days and across seasons if relevant.
  • Misreporting can be minimised through researcher prompts or mid-diary contact (e.g. by telephone) to offer support, prompt, answer any queries and by standard checks/questions on collection for any missed entries.
  • Not suitable for retrospective study, or distant past meals.
  • Labour-intensive for long term dietary intake or measuring intake of irregular consumed foods as would need multi-day diaries collected at multiple times spread over a year period.
  • Potential reactivity (likelihood of changes to usual food choice and omissions), increasingly likely as number of diary days increases.
  • Risk of lower completion rate of diaries as number of diary days increases.
  • Good literacy and numeracy needed unless research assistant or proxy (or carer/parent for children, elderly or translator) completes on behalf of participant.
  • High participant burden, especially if required to complete over several days and weigh foods.
  • Potential selection bias introduced as not all people are willing/able to complete a diet diary.
  • Moderate-to-high researcher burden, especially with manual coding which is very labour intensive requiring training and standardised QA/QC processes.
  • Generally expensive to code (solved to some extent by emerging technologies).
  • Estimated food diaries rely mostly on individual’s ability to describe portion sizes (photographs and food models can help address this).Participant may complete as a recall.

Food Diaries
Prospective, short-term methods where details of all foods and drinks are recorded by the participant as they are consumed, usually over several days. Amount of food eaten can be either estimated using household measures (estimated food diary) or weighed by the respondent or research assistant in the home (weighed food diary). It can be long term method if carried out multiple times, i.e. over multiple phases. Also known as food records or diet records. Can be completed online (see emerging technologies section).

Strengths
  • Provides detailed data on all food and drink consumption and portion size description, leading to good estimates of short term total dietary intake and total nutrient intake if completed thoroughly and nutritional supplement use is assessed.
  • Allows collection of contextual information (e.g. meal timing, location, brand, eaten with whom, TV/computer/device etc.).
  • Provides food and nutrient data that can be used in numerous types of analysis to answer a variety of research questions.
  • Potentially little reliance on memory when completed prospectively i.e. when food is consumed or soon after.
  • Weighed food diaries - weight of ingredients, final cooked weight and food waste can be measured leading to detailed information of consumption and good estimation of actual intakes of individuals.
  • Design of diary can include prompts to ensure inclusion of different eating occasions (including snacks) and pictures to help gauge portion sizes therefore enabling more comprehensive data.
  • Reasonably cheap to collect data (although traditionally coding is time-consuming and expensive).
  • Use of standardised instructions and coding rules with skilled researchers will help improve accuracy.
  • Multiple food diaries - can be used to estimate usual intakes of individuals and distributions in a group if administered over a sufficient number of non-consecutive days and across seasons if relevant.
  • Misreporting can be minimised through researcher prompts or mid-diary contact (e.g. by telephone) to offer support, prompt, answer any queries and by standard checks/questions on collection for any missed entries.

Weaknesses
  • Not suitable for retrospective study, or distant past meals.
  • Labour-intensive for long term dietary intake or measuring intake of irregular consumed foods as would need multi-day diaries collected at multiple times spread over a year period.
  • Potential reactivity (likelihood of changes to usual food choice and omissions), increasingly likely as number of diary days increases.
  • Risk of lower completion rate of diaries as number of diary days increases.
  • Good literacy and numeracy needed unless research assistant or proxy (or carer/parent for children, elderly or translator) completes on behalf of participant.
  • High participant burden, especially if required to complete over several days and weigh foods.
  • Potential selection bias introduced as not all people are willing/able to complete a diet diary.
  • Moderate-to-high researcher burden, especially with manual coding which is very labour intensive requiring training and standardised QA/QC processes.
  • Generally expensive to code (solved to some extent by emerging technologies).
  • Estimated food diaries rely mostly on individual’s ability to describe portion sizes (photographs and food models can help address this).Participant may complete as a recall.

24Hr Recalls

Strengths

Weaknesses
Retrospective, short-term method where details of foods and drinks consumed over previous 24 hours recalled. Can be administered by an interviewer (face to face or by telephone) following a standardised protocol. Can be administered as a single recall (for group-level assessment) or on multiple days (multiple recall) (required to capture individual variation). It can be used as a long term method if carried out over multiple phases. Can be completed online (see emerging technologies section).
  • Provides detailed data leading to good estimates of short-term (past day) total dietary intake and total nutrient intake if completed well and if nutritional supplement use assessed.
  • Multiple 24hr recalls - can be used to estimate usual intakes of individuals and distributions in a group if administered over a sufficient number of non-consecutive days and across seasons if relevant.
  • Allows collection of extra information (e.g. meal timing, frequency, location, brands eaten with whom, TV/computer/device etc.).
  • Provides flexible food and nutrient data that can be used in numerous types of analysis to answer a variety of research question.
  • Literacy and cultural issues minimised with trained interviewer.
  • If unannounced, element of surprise may lower reactivity i.e. changes to food intake because of measurement.
  • Moderate participant burden and high compliance depending on number of recall days.
  • Use of standardised protocols with skilled interviewer and multi-pass methods will help improve accuracy.
  • Not suitable for measuring distant past meal or irregularly consumed foods.
  • Unsuitable for participants with memory issues.
  • Forgotten items are common. Intrusions (items not consumed) can also occur.
  • A single 24hr recall is unable to account for day to day variation.
  • Single 24 hr recall - fails to identify irregularly consumed foods and therefore intake of some nutrients can be underestimated.
  • Moderate-to-high researcher burden, especially with manual coding, requiring training and standardised QA/QC processes.
  • Expensive if face-to-face interview required and large number of participants.
  • 24 hour recalls rely completely on an individual’s ability to describe portion sizes (photographs and food models can help address this).

24Hr Recalls
Retrospective, short-term method where details of foods and drinks consumed over previous 24 hours recalled. Can be administered by an interviewer (face to face or by telephone) following a standardised protocol. Can be administered as a single recall (for group-level assessment) or on multiple days (multiple recall) (required to capture individual variation). It can be used as a long term method if carried out over multiple phases. Can be completed online (see emerging technologies section).

Strengths
  • Provides detailed data leading to good estimates of short-term (past day) total dietary intake and total nutrient intake if completed well and if nutritional supplement use assessed.
  • Multiple 24hr recalls - can be used to estimate usual intakes of individuals and distributions in a group if administered over a sufficient number of non-consecutive days and across seasons if relevant.
  • Allows collection of extra information (e.g. meal timing, frequency, location, brands eaten with whom, TV/computer/device etc.).
  • Provides flexible food and nutrient data that can be used in numerous types of analysis to answer a variety of research question.
  • Literacy and cultural issues minimised with trained interviewer.
  • If unannounced, element of surprise may lower reactivity i.e. changes to food intake because of measurement.
  • Moderate participant burden and high compliance depending on number of recall days.
  • Use of standardised protocols with skilled interviewer and multi-pass methods will help improve accuracy.

Weaknesses
  • Not suitable for measuring distant past meal or irregularly consumed foods.
  • Unsuitable for participants with memory issues.
  • Forgotten items are common. Intrusions (items not consumed) can also occur.
  • A single 24hr recall is unable to account for day to day variation.
  • Single 24 hr recall - fails to identify irregularly consumed foods and therefore intake of some nutrients can be underestimated.
  • Moderate-to-high researcher burden, especially with manual coding, requiring training and standardised QA/QC processes.
  • Expensive if face-to-face interview required and large number of participants.
  • 24 hour recalls rely completely on an individual’s ability to describe portion sizes (photographs and food models can help address this).

Food Frequency Questionnaires

Strengths

Weaknesses
Retrospective methods querying frequency over periods of time, questions relate to the frequency with which foods and drinks have been consumed over a long time period (weeks, months, and years). Can be ‘qualitative’ (frequency only), ‘semi-quantitative’ (estimated portion pre-assigned e.g. small, average, large) or ‘fully quantitative’ (portion size queried). Can be long (comprehensive, around 100 items queried or more) or short (also known as ‘screeners’ or a type of brief instrument). Can be interviewer- or self-administered, completed on paper (with potential scanning option) or online (see emerging technologies).
  • Useful for estimating long term usual intakes of foods retrospectively; ranking participants into intake levels; estimating foods consumed irregularly.
  • Useful in large population studies as low researcher burden, potential low cost and low participant burden (higher response rates).
  • Long FFQs- potential for estimating usual dietary intake and total nutrient intake if portion size and dietary supplement use queried.
  • Short FFQs - suitable for estimating intake of small number of specific food items. Highly efficient approach when study has specific hypothesis to test, for example FFQ designed to determine calcium will contain only foods which provide calcium.
  • Short FFQs - low participant burden as quick to complete.
  • Coding generally less intensive.
  • Not suitable for cross-cultural or cross-country comparisons unless comparable food lists included.
  • Short FFQs - not reliable for measuring total diet, total energy intakes and total nutrient intakes.
  • Requires good participant memory, literacy and numerical skills (e.g. to average intakes over long period of time) which can lead to inaccurate or subjective reporting.
  • Accurate reporting of frequencies and portions may be particularly difficult in children without parent/carer assistance.
  • Prone to mis-reporting if not carefully designed, especially for long FFQs.
  • Restricted to items that are specifically listed in the instrument.
  • It would not be possible to disaggregate foods which are listed together.
  • Requires specific algorithms in software to convert frequencies to nutrients.

Food Frequency Questionnaires
Retrospective methods querying frequency over periods of time, questions relate to the frequency with which foods and drinks have been consumed over a long time period (weeks, months, and years). Can be ‘qualitative’ (frequency only), ‘semi-quantitative’ (estimated portion pre-assigned e.g. small, average, large) or ‘fully quantitative’ (portion size queried). Can be long (comprehensive, around 100 items queried or more) or short (also known as ‘screeners’ or a type of brief instrument). Can be interviewer- or self-administered, completed on paper (with potential scanning option) or online (see emerging technologies).

Strengths
  • Useful for estimating long term usual intakes of foods retrospectively; ranking participants into intake levels; estimating foods consumed irregularly.
  • Useful in large population studies as low researcher burden, potential low cost and low participant burden (higher response rates).
  • Long FFQs- potential for estimating usual dietary intake and total nutrient intake if portion size and dietary supplement use queried.
  • Short FFQs - suitable for estimating intake of small number of specific food items. Highly efficient approach when study has specific hypothesis to test, for example FFQ designed to determine calcium will contain only foods which provide calcium.
  • Short FFQs - low participant burden as quick to complete.
  • Coding generally less intensive.

Weaknesses
  • Not suitable for cross-cultural or cross-country comparisons unless comparable food lists included.
  • Short FFQs - not reliable for measuring total diet, total energy intakes and total nutrient intakes.
  • Requires good participant memory, literacy and numerical skills (e.g. to average intakes over long period of time) which can lead to inaccurate or subjective reporting.
  • Accurate reporting of frequencies and portions may be particularly difficult in children without parent/carer assistance.
  • Prone to mis-reporting if not carefully designed, especially for long FFQs.
  • Restricted to items that are specifically listed in the instrument.
  • It would not be possible to disaggregate foods which are listed together.
  • Requires specific algorithms in software to convert frequencies to nutrients.

Food Checklists

Strengths

Weaknesses
Also known as a type of ‘brief instrument’, ‘screeners’ or ‘short instruments’. Prospective, short-term method where specified foods and drinks are ticked from a list as they are consumed over a day or number of days; frequency can be queried; option to query portion sizes or pre-assign them. This is a less used method that has a lot of strengths and weaknesses in common with the longer FFQ. Can be completed online (see emerging technologies).
  • Can be suitable for estimating intakes of specific foods or nutrients occurring in high levels in specific foods.
  • Can be useful for comparing short-term group mean intakes of a small group of items, patterns, change over time, compliance with dietary guidelines and providing dietary advice.
  • Low researcher and participant burden, low cost.
  • Coding generally simple.
  • Generally brief so unsuitable for measuring total diet, total nutrient and energy intake.
  • Not suitable for cross-cultural or cross-country comparisons unless comparable food lists included.
  • Restricted to items that are specifically listed in the instrument.

Food Checklists
Also known as a type of ‘brief instrument’, ‘screeners’ or ‘short instruments’. Prospective, short-term method where specified foods and drinks are ticked from a list as they are consumed over a day or number of days; frequency can be queried; option to query portion sizes or pre-assign them. This is a less used method that has a lot of strengths and weaknesses in common with the longer FFQ. Can be completed online (see emerging technologies).

Strengths
  • Can be suitable for estimating intakes of specific foods or nutrients occurring in high levels in specific foods.
  • Can be useful for comparing short-term group mean intakes of a small group of items, patterns, change over time, compliance with dietary guidelines and providing dietary advice.
  • Low researcher and participant burden, low cost.
  • Coding generally simple.

Weaknesses
  • Generally brief so unsuitable for measuring total diet, total nutrient and energy intake.
  • Not suitable for cross-cultural or cross-country comparisons unless comparable food lists included.
  • Restricted to items that are specifically listed in the instrument.

Diet Histories

Strengths

Weaknesses
Combination of short-term and long-term methods, usually 24hr recall, FFQ and food diary; more often used in a clinical setting by experienced dieticians to provide in-depth assessment at individual level.
  • Potential for estimating usual intakes of foods and nutrients if over long period (e.g. 1 month or more) depending on balance of days.
  • Ability to assess meal patterns and food preparation over extended period of time.
  • Some diet history instruments have been automated and adapted for self-administration.
  • Protocols tend to vary as no agreed standardised approach available, food records and 24HRs are sometimes used to check the diet history with detailed questions about usual eating patterns by meal.
  • The meal-based approach is not suitable for individuals who have no regular eating pattern.
  • High participant burden.
  • High researcher burden, as the interview and the food list component each can take up to an hour to complete.
  • Complex analysis processes required.
  • Generally expensive as it requires trained interviewer and coding the data.

Diet Histories
Combination of short-term and long-term methods, usually 24hr recall, FFQ and food diary; more often used in a clinical setting by experienced dieticians to provide in-depth assessment at individual level.

Strengths
  • Potential for estimating usual intakes of foods and nutrients if over long period (e.g. 1 month or more) depending on balance of days.
  • Ability to assess meal patterns and food preparation over extended period of time.
  • Some diet history instruments have been automated and adapted for self-administration.

Weaknesses
  • Protocols tend to vary as no agreed standardised approach available, food records and 24HRs are sometimes used to check the diet history with detailed questions about usual eating patterns by meal.
  • The meal-based approach is not suitable for individuals who have no regular eating pattern.
  • High participant burden.
  • High researcher burden, as the interview and the food list component each can take up to an hour to complete.
  • Complex analysis processes required.
  • Generally expensive as it requires trained interviewer and coding the data.

Emerging Technologies

Strengths

Weaknesses
Dietary data collected and processed making use of hardware plus software (e.g. devices such as sensors and optical readers) or software such as web-based versions and apps based on traditional DATs. More advanced method of collecting data, which could be based on traditional methods (FFQs, food diary or 24 h recall). It is a rapidly evolving area.
  • Potential for providing ‘real time’ food/nutrient results output.
  • Potential for enhanced portion size and food waste estimation (using digital capturing of meals and photos).
  • Potential for low to moderate participant burden and higher participant motivation (depending on the participants’ technological ability and the technology itself).
  • Potential to prompt recording to reduce mis-recording.
  • Online versions of recalls, diaries and FFQs may be useful for large sample sizes due to lower researcher burden (e.g. interviewers, data entry, manual coding, printing may not be required).
  • As with all recently developed DATs, validation/calibration data may not yet have been generated for evaluating DAT quality.
  • Likely to inherit similar measurement error to non-adapted version (e.g. paper-based vs web-based FFQ).
  • Internet, computer and mobile-technology skills and access required.
  • Participant training required if tool not intuitive.
  • Potential high initial cost of specialised equipment and software programming.

Emerging Technologies
Dietary data collected and processed making use of hardware plus software (e.g. devices such as sensors and optical readers) or software such as web-based versions and apps based on traditional DATs. More advanced method of collecting data, which could be based on traditional methods (FFQs, food diary or 24 h recall). It is a rapidly evolving area.

Strengths
  • Potential for providing ‘real time’ food/nutrient results output.
  • Potential for enhanced portion size and food waste estimation (using digital capturing of meals and photos).
  • Potential for low to moderate participant burden and higher participant motivation (depending on the participants’ technological ability and the technology itself).
  • Potential to prompt recording to reduce mis-recording.
  • Online versions of recalls, diaries and FFQs may be useful for large sample sizes due to lower researcher burden (e.g. interviewers, data entry, manual coding, printing may not be required).

Weaknesses
  • As with all recently developed DATs, validation/calibration data may not yet have been generated for evaluating DAT quality.
  • Likely to inherit similar measurement error to non-adapted version (e.g. paper-based vs web-based FFQ).
  • Internet, computer and mobile-technology skills and access required.
  • Participant training required if tool not intuitive.
  • Potential high initial cost of specialised equipment and software programming.