While this seems like a harmless enough fib, researchers at the University College of Cork in Ireland have found that it can present problems as to how obesity is calculated. For large-scale epidemiological studies, self-reports are the norm, but the Irish researchers have found that the gap between obesity levels that are calculated based on self-reports and those based on clinical measures are increasing.

Findings also showed that obese men tend to underestimate their weight more than overweight men, while both overweight and obese women shed kilos from their self reports.

To a lesser extent, people also tend to add a few centimeters to their height, particularly men and older women, noted the researchers.

The study was published online January 23 in the journal PLOS One.

Another study published last year from the University of Utah found that people tend to lie when confronted with surveys asking for height and weight, but the mistruths weren't enough to skew data on obesity levels.