Trends in energy and macronutrient intakes in non-under-reporters vary with the method used to identify under-reporters

Objective: To investigate effects of using different methods to identify under-reporters on trends in dietary intake and physical activity level (PAL) in non-under-reporters. Design: Dietary intake and activity pattern were recorded by 887 female university students from 1988 to 2003. Energy expenditure (EE) and PAL were measured using a factorial method. Nine methods were used to identify under-reporters. Trends between 1988 and 2003 were determined from linear regression of median data for each year. Results: Prevalence of under-reporting varied with the method used, ranging from 22.2% to 66.7%. Trends that were consistent using all methods were a decrease in per cent of energy from fat and no change in alcohol intake or PAL (P < 0.05). Trends in energy and macronutrient intakes varied with the method used. Using the four methods that excluded the most under-reporters there were increases in energy and gram carbohydrate (CHO) intakes (P < 0.05), but no change in gram fat intake. Using the four methods that excluded the fewest under-reporters there was no change in energy or gram CHO intake, but a decrease in gram fat intake (P < 0.05). Conclusion: Trends in energy, fat and CHO intakes in non-under-reporters varied with the method used to identify under-reporters.