Weight misperception has been reported as a common problem in high-income countries, but there is a paucity of high-quality empirical evidence in low- and middle-income countries, especially among children and adolescents. This study estimates the prevalence of weight misperception and investigates changes over time among children and adolescents in China, as well as identifies factors that may affect this weight misperception.

The China Health and Nutrition Survey, which is a repeated, representative cross-sectional study employing multistage random cluster processes.

A Chinese national survey across fifteen provinces and municipal cities.

Data from children and adolescents aged 6–16 years from six consecutive waves between 2000 and 2015 were included.

The final sample totalled 7110 children and adolescents. The overall prevalence of weight misperception was largely stable between 2000 and 2015 (range: 34·1–37·3 %). Sex and age groups were associated with weight misperception, with boys and younger participants more likely to misperceive their weight status. In addition, dieting and being physically active or inactive were associated with increased rates of weight misperception.

Weight misperception is common among youth in China and is unequally shared with several subpopulations at increased risk. Researchers and health promoters are called to recognise weight misperception when addressing overweight and obesity countermeasures, and more tailored public health initiatives are warranted to more effectively reach those with weight misperceptions.

To evaluate weight misperception among adolescents and determine associations between self-perceived weight and socio-demographic characteristics, BMI, screen time, self-rated food quantity and diet quality, weekly frequency of breakfast and the consumption of healthy and unhealthy foods.

A cross-sectional, two-stage, probabilistic population-based study was conducted in Campinas, Brazil. Multinomial logistic regressions were run to estimate weight self-perception.

Data from the Campinas Health Survey (ISACamp) and Campinas Food Consumption Survey (ISACamp-Nutri).

A total of 911 adolescents aged 10–19 years.

Nearly half (47·7 %) of the adolescents with overweight/obesity did not evaluate their weight properly. Weight self-perception as thin and excess weight was associated with the female gender, overweight/obesity, self-rated diet quality as poor/very poor and eating snacks ≥3 times/week. Adolescents who did not consume breakfast daily were less likely to perceive themselves as thin. Adolescents who ate excessively were more likely and those who consumed cookies/crackers ≥3 times/week were less likely to perceive themselves as having excess weight.

Greater weight misperception was found in overweight/obese adolescents. Gender, BMI, self-rated food quantity/diet quality, weekly frequency of breakfast and some unhealthy foods were associated with self-perceived weight. The present findings could contribute to health promotion strategies targeting adolescents.