Underestimation and overestimation of personal weight status: associations with socio-demographic characteristics and weight maintenance intentions J. Brug,* B. Wammes,* S. Kremers, K. Giskes* & A. Oenema* *Department of Public Health, Erasmus University Medical Center, Rotterdam, The Netherlands;  Department of Health Education and Promotion, Maastricht University, Maastricht, The Netherlands Ó The British Dietetic Association Ltd 2006 J Hum Nutr Dietet, 19, pp. 253–262 253 Correspondence Johannes Brug, Department of Public Health, Erasmus University Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands. Tel.: +31 10 4638460 Fax: +31 10 4638475 E-mail: j.brug@erasmusmc.nl Keywords intentions, misconception, SES, weight status. Abstract Objective Unwarranted underestimation and overestimation of personal weight status may prevent weight maintenance behaviour. The present study reports on correlates of under- and overestimation of personal weight status and the association with weight mainten- ance intentions and self-reported action. Design Comparison of three cross-sectional surveys, representing different population groups. Subjects Survey 1: 1694 adolescents 13–19 years of age; survey 2: 979 nonobese adults 25–35 years of age; survey 3: 617 adults 21– 62 years of age. Measurements Self-administered written questionnaires (surveys 1 and 3) and telephone-administered questionnaires (survey 2); self- reported BMI, self-rated weight status, intentions and self-reported actions to avoid weight gain or to lose weight, sex, age, education and ethnic background. Respondents were classified as people who are realistic about personal body weight status or people who under- and overestimate their body weight status, based on BMI and self-rated weight status. Results Most respondents in the three survey populations were realistic about their weight status. Overestimation of weight status was consistently more likely among women, whereas underestima- tion was more likely among men, older respondents and respondents from ethnic minorities. Self-rated weight status was a stronger cor- relate of intentions and self-report actions to avoid weight gain than weight status based on Body Mass Index.