Primary pupils in England’s poorest areas are four times more likely to be severely obese than in the wealthiest.
In Reception, 12.5% of them are obese, compared with 5.7% of those in the richest areas. And by Year 6 these figures have risen to 26.8% and 11.7%.
Obese children are more likely to be bullied, stigmatised and have low self-esteem, Public Health England says.
And they are more likely to stay overweight, raising their risk of heart disease, type-2 diabetes and cancer.
Overall, the proportion of severely obese Year 6 pupils has risen from 3.6% in 2009-10 to 4.2% in 2017-18.
The proportion who are obese has risen from 20% in 2016-17 to 20.1% in 2017-18 – 22.2% of the boys and 18% of the girls.
In Reception, 2.4% are severely obese, while the proportion who are obese has stayed static at 9.5% – and they too are more likely to be boys.
Three-quarters are a healthy weight – but this drops to two-thirds by Year 6.
The report comes from the National Child Measurement Programme, which tracks the height and weight of children in state primary schools in England.