Child obesity cut-offs as derived from parental perceptions: cross-sectional questionnaire.

BACKGROUND: Overweight children are at an increased risk of premature mortality and disease in adulthood. Parental perceptions and clinical definitions of child obesity differ, which may lessen the effectiveness of interventions to address obesity in the home setting. The extent to which parental and objective weight status cut-offs diverge has not been documented. AIM: To compare parental perceived and objectively derived assessment of underweight, healthy weight, and overweight in English children, and to identify sociodemographic characteristics that predict parental under- or overestimation of a child's weight status. DESIGN AND SETTING: Cross-sectional questionnaire completed by parents linked with objective measurement of height and weight by school nurses, in English children from five regions aged 4-5 and 10-11 years old. METHOD: Parental derived cut-offs for under- and overweight were derived from a multinomial model of parental classification of their own child's weight status against school nurse measured body mass index (BMI) centile. RESULTS: Measured BMI centile was matched with parent classification of weight status in 2976 children. Parents become more likely to classify their children as underweight when they are at the 0.8th centile or below, and overweight at the 99.7th centile or above. Parents were more likely to underestimate a child's weight if the child was black or South Asian, male, more deprived, or the child was older. These values differ greatly from the BMI centile cut-offs for underweight (2nd centile) and overweight (85th). CONCLUSION: Clinical and parental classifications of obesity are divergent at extremes of the weight spectrum.