Almost one in ten children starting school are dangerously overweight, according to the latest figures from Public Health England - and the number is on the rise.
The health authority's National Child Measurement Programme shows obesity has increased for the second year in a row in reception year children in 2016 to 2017, up from 9.3% to 9.6%.
For children in their last year of primary school the number has remained stable at one in five who are obese.
The report comes as food and drink companies prepare to lower sugar content in their products when the Soft Drinks Industry Levy becomes law next year.
The figures also reveal a wide gap between the richest and poorest - in the poorest areas 12.7% of children in reception year are obese compared to 5.8% in the least deprived, while at the end of primary school the difference is even bigger.
Dr Alison Tedstone, chief nutritionist at PHE, said: 'Children deserve a healthy future and these figures are a reminder that addressing childhood obesity requires urgent action.
'There is no single solution to reverse what’s been decades in the making. We need sustained actions to tackle poor diets and excess calorie intakes.
'We’re working with industry to make food healthier, we’ve produced guidance for councils on planning healthier towns and we’ve delivered campaigns encouraging people to choose healthier food and lead healthier lives.'