Of particular importance to nutrition surveys is a widely observed tendency for people to under-report their food intake. This can include:
- actual changes in foods eaten because people know they will be participating in the survey
- misrepresentation (deliberate, unconscious or accidental), e.g. to make their diets appear more ‘healthy’ or be quicker to report.
In order to assist in the interpretation of data from the 2011-12 National Nutrition and Physical Activity Survey (NNPAS) and particularly in comparisons with the 1995 National Nutrition Survey ( NNS), Australian Bureau of Statistics (ABS) analysed the potential under-reporting prevalence in different population sub-groups and estimated how much energy might be missing from the food recall data. See details in Under-reporting in Nutrition Surveys
in the Australian Health Survey (AHS) Users' Guide.
In summary, the analysis suggests that:
- It is likely that under-reporting is present in both surveys.
- There appears to be an increase in the level under-reporting for males between 1995 and 2011-12, especially for males aged 9 - 50.
- The level of under-reporting by female respondents also appears to have increased, but to a lesser extent than for males.
- In order to achieve an Energy Intake to Basal Metabolic Rate Ratio (EI:BMR) ratio of 1.55 which is the amount required for a normally active but not sedentary population, an increase in mean energy intake of 17% for males and 21% for females is required and greater increases are required for overweight and obese people than those of normal weight.
- Given the association of under-reporting with overweight/obesity and consciousness of socially acceptable/desirable dietary patterns, under-reporting is unlikely to affect all foods and nutrients equally.
There is still further work that can be conducted in this area. In particular, the investigation into the impact of under-reporting on the change in consumption patterns of different foods can be expanded.