Misreporting dietary intake

Misreporting dietary intake is more common than you think. This becomes an issue when we try to draw health, body composition and/or performance associations based on inaccurate data.

The reasons for misreporting vary (not everyone lies on purpose) and does the level of misreporting (i.e. how far off are the reported vs “real” values). However, there are clear trends: for example, most people tend to underreport (say they ate less than they did) than overreport.

What is misreporting dietary intake?

Misreporting is failing to report with accuracy how much a person ate.

Underreporting means reporting less than the actual amount, overreporting means reporting more than the actual amount.

In science, how the actual amount is measured depends on the study. Some of the methods are more susceptible to error due to assumptions, leading to variations in the magnitude and direction of misreporting (1). In other words, it is hard to tell if people are misreporting and how far off they are from reality. However, it is safe to assume that, unless every single morsel of food a person consumes is weighed and measured, there will be inaccuracies.

Who is more likely to underreport?

• People with higher BMI, weight or adipose tissue (1, 2, 3, 4)
• People with lower socio-economic status and education (2)
• Women (1, 2, 3), although some studies have found older women less likely to underreport (4) and others have found no differences between men and women (5)
• Older individuals (1, 2)
• Children and adolescents (1, 3)
• Smokers (2)
• People who are on a diet (1, 2)
• People who eat more (2)
• People with depression or anxiety (1)

Who is more likely to overreport?

• Younger children assisted by their parents (3)

How many people misreport dietary intake?

Underreporting

The proportion of underreporters vary with recording method, sex and age.

• 24 hour recall: 21.5-67% (18-61% men, 4-72% women) (2)
• Estimated food records: 11.9-44% (14.3-42% men, 7.6-49% women) (2)
• Weighed food records: 14.3-38.5% (2)
• Food frequency questionnaires: >=28% (30.5% men, 25.7% women) (1)
• Children and adolescents: 2-85% (3)

Methods that use technology, especially digital photos, tend to be more accurate (1, 5).

Overreporting

The proportion of overreporters also vary with recording method, sex and age.

• 24 hour recall: 1.6% men, 1-6% women (2)
• Estimated food records: 3.5-7% (2)
• Weighed food records: nil (2)
• Children and adolescents: 3-46% (3)

How far off are reported values?

Underestimation

The amount of underestimation vary with recording method, sex and age. In some cases it is expressed as a percentage of actual intake, in some cases as an absolute value.

• 24 hour recall
  • 12.8%-14% for adults (2)
  • 2650 kJ/633 kcal per day for women (5)
  • 2993 kJ/715 kcal per day for men (5)
  • <5% for children and adolescents (3)
• Estimated food records
  • 7.2-20% for adults (2)
  • 11-46% for children and adolescents (3)
  • 1829 kJ/437 kcal per day for women (5)
  • 2468 kJ/590 kcal per day for men (5)
• Weighed food records
  • 10.4-20.2% for adults (2)
  • 2286 kJ/546 kcal per day for women (5)
  • 3438 kJ/822 kcal per day for men (5)
• Food frequency questionnaires
  • 1318 kJ/315 kcal per day women (5)
  • 1764 kJ/422 kcal per day for men (5)

Overestimation

• 24 hour recall
  • 6.7-11% for men (2)
  • 9.3-13% for women (2)
  • >10% for children and adolescents (3)
• Estimated food records
  • nil (2)
• Weighed food records
  • 14.3-38.5% for adults (2)

Why do people misreport dietary intake?

• Forgetfulness: this is an important factor when using methods that require people to recall what they ate, rather than to record their intake in real time (2, 1)
• Recording fatigue: if you have ever kept a food log you know it can be a very tedious process (1)
• Inaccurate portion sizes: most people will make mistakes when estimating quantities when not actually weighing/measuring the food they consume (1, 2)
• Wanting to meet “healthy” ideals (2)
• Omitting mid-meal snacks (4), which can be a consequence of any of the factors above
• Lack of awareness of the energy content of foods (5)

What type of foods do people misreport?

There is evidence that the food groups that people tend to underreport include: milk, milk-based drinks and cream, fruit, water and drinks, sandwiches and bread (weighed dietary records and 24-hour recall), fruit juices, breakfast cereals, meat and biscuits (24-hour recall only) (6).

On the other hand, some studies have found people tend to overreport intake of fruits and vegetables (1).

Summary and recommendations

• Misreporting is common when collecting dietary intake
• Misreporting can refer to underreporting or overreporting, however the former is more common than the latter
• Factors for misreporting include forgetfulness, recording fatigue and lack of awareness of portion sizes and energy content of foods
• Groups of people that tend to underreport include: those with higher BMI, women, older adults, and children and adolescents
• The proportion of people who misreport dietary intake and the level of misreporting vary with recording method, population, method of determining actual intake, etc.
• When using reported dietary intake to inform health recommendations at the population or individual level, we need to keep in mind the data may be inaccurate to a degree
• Education on portion sizes can reduce reporting errors
• When possible, try to use methods that seem to be more accurate and use technology (including photos) to improve the accuracy

References

1. Castro-Quezada I, Ruano-Rodríguez C, Ribas-Barba L, Serra-Majem L. Misreporting in nutritional surveys: methodological implications. Nutr Hosp. 2015 Feb;31 Suppl 3:119–27.
2. Poslusna K, Ruprich J, de Vries JHM, Jakubikova M, van’t Veer P. Misreporting of energy and micronutrient intake estimated by food records and 24 hour recalls, control and adjustment methods in practice. Br J Nutr [Internet]. 2009;101(S2):S73-85.
3. Forrestal SG. Energy intake misreporting among children and adolescents: a literature review. Matern Child Nutr. 2011 Apr;7(2):112–27.
4. Shahar DR, Yu B, Houston DK, Kritchevsky SB, Newman AB, Sellmeyer DE, et al. Misreporting of energy intake in the elderly using doubly labeled water to measure total energy expenditure and weight change. J Am Coll Nutr. 2010 Feb;29(1):14–24.
5. McKenzie BL, Coyle DH, Santos JA, Burrows T, Rosewarne E, Peters SAE, et al. Investigating sex differences in the accuracy of dietary assessment methods to measure energy intake in adults: a systematic review and meta-analysis. Am J Clin Nutr. 2021 May;113(5):1241–55.
6. Garden L, Clark H, Whybrow S, Stubbs RJ. Is misreporting of dietary intake by weighed food records or 24-hour recalls food specific? Eur J Clin Nutr. 2018 Jul;72(7):1026–34.

[Photo by Chad Stembridge on Unsplash]

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