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
§ the misrepresentation of foods and beverages consumed (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 2012-13 National Aboriginal and Torres Strait Islander Nutrition and Physical Activity Survey (NATSINPAS) and also in making comparisons with the 2011-12 National Nutrition and Physical Activity Survey (NNPAS), 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 the National Aboriginal and Torres Strait Islander Nutrition and Physical Activity Survey in the Users' Guide.
In summary, the analysis shows that:
§ Under-reporting is likely to have occurred in both surveys.
§ When compared with results for the total population from the 2011-12 NNPAS, there was a higher proportion of Low Energy Reporters (LERs) for both Aboriginal and Torres Strait Islander males and females in NATSINPAS.
§ The proportion of Aboriginal and Torres Strait Islander people who were classed as LERs increased with Body Mass Index (BMI) for both males and females, with females more likely to be low energy reporters than males.
§ The BMI distribution of the NATSINPAS population differs from the NNPAS population, for example almost two fifths (39%) of the NATSINPAS population is obese, compared with 25% of the NNPAS population. Differences in the BMI distributions may be a potential driver of differences in under-reporting between the two populations.
§ In order for each member of the Aboriginal and Torres Strait Islander population to achieve an Energy Intake to Basal Metabolic Rate Ratio (EI:BMR) ratio of 1.55 which is the ratio expected for a normally active but sedentary population, an increase in mean energy intake of 24% for males and 31% for females would be required with greater increases required for overweight and obese people than for those of normal weight. This compares to 17% for males and 21% for females in the NNPAS population.
§ Given the association of under-reporting with overweight/obesity and consciousness of socially acceptable/desirable dietary patterns, under-reporting is unlikely to have affected the results for all foods and nutrients equally.