A failure to correctly perceive weight was very frequent among children and their mothers, especially when children were overweight. These factors could represent obstacles to correctly recognizing nutritional abnormalities.

Objective: To describe and compare maternal perception and the self-perception of children/adolescents of their nutritional status, identifying factors associated with incorrect perceptions. Methods:Cross-sectional study carried out in Salvador, BA, Brazil with 1,741 students aged 6 to 19 years, classified according to body mass index (BMI) percentiles as underweight (BMI < p5), well-nourished (p5 ≤ BMI < p85), at risk of overweight (p85 ≤ BMI < p95) or overweight (BMI ≥ p95). Students and their mothers answered questions on perception of weight, patterns of physical exercise and dieting. By means of multivariate analysis, factors associated with incorrect maternal and self-perceptions were analyzed.Results: Self-perceptions were correct in 64.7% of cases and 75.3% of maternal perceptions were correct. The principal factor associated with incorrect self-perception was age between 6 and 9 years (OR = 1.59; 95%CI 1.15-2.20). Among girls, being overweight and practicing physical exercise were characteristics associated with better perception. For boys, the presence of overweight resulted in an increased risk of incorrect self-perception.Among mothers, having an overweight child (OR = 3.02; 95%CI 2.05-4.46) and a child aged from 6 to 9 years (OR = 1.88; 95%CI 1.28-2.76) were associated with incorrect perception. Conclusions:A failure to correctly perceive weight was very frequent among children and their mothers, especially when children were overweight. These factors could represent obstacles to correctly recognizing nutritional abnormalities.J Pediatr (Rio J). 2007;83(4):349-356: Body image, overweight, childhood obesity, physical activity, adolescent.