Self-reported food intake may compromise research findings
accuracy of research into the impact of certain foods on obesity
and diabetes, suggests a new report.
An investigation into the diets of 200 women with type 2 diabetes found that most of the subjects reported eating less calories than they had. "Widespread energy underreporting among this group…severely compromised the validity of self-reported dietary data," write the authors in this month's Diabetes Care (27:663-669).
Underestimated calories means that it is difficult to measure the efficacy of dietary interventions, being widely studied by the functional food and supplements industry. The new findings point to the importance of using some objective measure to back up research participants' dietary claims, said the authors.
The researchers from the University of North Carolina at Chapel Hill assessed the energy intake of middle-aged African-American women with type 2 diabetes by three telephone-administered 24-hour diet recalls. They then measured physical activity over a seven-day period by accelerometer, which also provided an estimate of total energy expenditure.
Comparing the self-reported energy intake with total energy expenditure, the researchers found 81 per cent of participants had not reported full energy intake. They also compared the reported data with basal metabolic rate and this revealed that 58 per cent had underreported their energy intake.
Energy underreporters had significantly lower reported fat, higher protein, but similar carbohydrate intakes compared with non-underreporters, added the researchers. And the more overweight, the more likely the woman was to claim a false energy intake.
Past research has shown that people who are overweight, or want to lose weight, may feel pressured to report better eating habits. Most of the study participants were in fact overweight or obese.
