Background: With studies around the world suggesting a large proportion of people do not recognise that they are overweight (or feel satisfied with being overweight), this fuels the view that such 'misperceptions' need to be 'corrected'. However, few longitudinal studies have examined the consequences of under-perceived weight status, nor over-perceived weight status (when a person feels overweight when they are not) and weight-related satisfaction on trajectories in body mass index (BMI).
Methods: Five-year BMI trajectories were examined among 8174 participants in an Australian nationally representative cohort. Each person was classified into groups according to their neighbourhood socioeconomic circumstances, baseline BMI and answers to "how satisfied are you with your current weight?" and "do you consider yourself to be… acceptable weight / underweight / overweight?" Gender-specific multilevel linear regressions were used to examine five-year BMI trajectories for people in each group, adjusting for potential confounders.
Results: At baseline, weight-related dissatisfaction and perceived overweight were generally associated with higher mean BMI for men and women, regardless of whether they were classified as 'normal' or overweight by World Health Organization (WHO) criteria. Mean BMI did not decrease among people classified as overweight who perceived themselves as overweight, or expressed weight-related dissatisfaction, regardless of where they lived. Among men and women with 'normal' BMI at baseline but expressing weight-related dissatisfaction, mean BMI increased disproportionately among those living in disadvantaged areas compared to their counterparts in affluent areas. Similarly, mean BMI rose disproportionately among people in disadvantaged areas who felt they were overweight despite having a 'normal' BMI by WHO criteria, compared to people with the same over-perceptions living in affluent areas. These differences exacerbated pre-existing socioeconomic inequities in mean BMI.
Conclusions: No evidence was found to suggest accurate recognition of overweight or expressing weight-related dissatisfaction leads to a lower BMI. However, there was evidence of an increase in mean BMI among people who felt dissatisfied with, or over-perceived their 'normal' weight, especially in socioeconomically disadvantaged areas. Correction of under-perceptions may not drive weight loss, but circumstances contributing to over-perception and dissatisfaction with weight status may contribute to increased weight gain and exacerbate socioeconomic inequities in BMI.