effects of weight misperception on the association between BMI and self-rated health in midlife and elderly Koreans

Objectives: This study aimed to find whether weight misperception affected the relationship between measured body mass index (BMI) and self-rated health (SRH) in middle-aged and senior Koreans. Methods: A cross-sectional study was conducted in 8397 men and 11,211 women aged 40-80 years from the 2014-2018 Korea National Health and Nutrition Examination Survey using gender and age group (40-59 years and 60-80 years) specific moderation analysis and ordinal regression analysis of complex sampling design. BMI and weight misperception were the predictor and moderator, respectively. Outcome measure was SRH graded on very good to very poor scale.Results: In the group with accurate body weight estimation, the odds ratio of poorer SRH was greater in underweight or obese men and women aged 40-59 years and women aged 60-80 years compared to normal weight. However, in men aged 60-80 years who accurately estimated their weight, the odds ratio was higher in the underweight group but not in obese group. In the group that overestimated body weight, the odds ratio increased as the BMI category increased. In the group underestimating body weight, the odds ratio decreased in overweight or obese group than in the normal weight group. Conclusions: Weight misperception in middle-aged and older Korean men and women altered the relationship between BMI category and poorer SRH. Individuals who accurately estimated themselves as underweight regardless of gender or age and those who correctly identified themselves as obese in their middle years were the most likely to have poorer SRH.