Extreme under-reporting of body weight by young adults with obesity: relation to social desirability

Objective The objective of this study was to determine whether there is an association between under-reporting of body weight and social desirability as is found with self-reports of energy intake. Methods Twenty-seven lean individuals (mean body mass indexstandard deviation = 21.6 +/- 2.0 kg m(-2)) and 26 individuals with obesity (mean body mass index = 35.4 +/- 4.8 kg m(-2)) were e-mailed a questionnaire on which they had to state their body weight and conduct a home food inventory. The next day, research team members went to their homes to weigh the participants, conduct their own food inventory and administer the Marlowe-Crowne scale for social desirability. Results Among individuals with obesity, lower social desirability scores were associated with a greater degree of under-reporting body weight (r = +0.48, p < 0.02). Among lean individuals, the correlation was negative but statistically non-significant (p = -0.22, p > 0.10). Nine individuals with obesity were extreme under-reporters (2.27 kg or more), and eight of these had social desirability scores in the bottom half of the Marlowe-Crowne scale (p < 0.01). Six under-reported on the home food inventory by three or more items. Conclusions Individuals with obesity and low social desirability scores are more likely than others to be extreme under-reporters of body weight, possibly due to a lack of awareness of their own weight.