Overweight and obesity in childhood and adolescence: findings from the UK Millennium Cohort Study, up to age 14

Background: The aims of this work are threefold: (1) Show the pathway of overweight and obesity, for the current generation of adolescents, since early childhood in the UK. (2) Identify factors associated with the risk of overweight/obesity at age 14. (3) Study transitions into and out of overweight/obesity, from early adolescence to mid-adolescence.Methods: A sample of 10,825 children in the UK Millennium Cohort Study was selected for analysis. BMI was calculated using measured height and weight available at every sweep since age three, and overweight and obesity were defined using the IOTF classification. Possible factors associated with the risk of excess weight include socio-demographic characteristics, early life circumstances, and behavioural and lifestyle factors in adolescence.Results: 19.2% of the sample of 14-year-olds in 2015/16 is classified as overweight (95% CI 18.4-20.0), and 7.5% as obese (95% CI 7.0-7.9), with proportions very similar across sexes. Protective factors for excess weight include high maternal education, breastfeeding, home ownership and child's active behaviour. The likelihood of transiting out of excess weight/obesity between ages 11 and 14 is higher than the likelihood of transiting in. Predictors of transiting out of excess weight/obesity include child's active behaviour and puberty onset by age 14.Conclusions: This study provides new evidence that the profile of rising trends in excess weight observed during childhood had stabilised by mid-adolescence. However, rates of excess weight remain high, and overweight and obesity in childhood and adolescence remain a major public health concern. The study identifies some risk and protective factors to reinforce the government commitment to reducing excess weight in childhood.