The proportion of 10 to 11-year-old children who are severely obese has reached a record high, according to new figures.

Just over 4% of Year 6 children are now severely obese, up from 3.2% 10 years ago. The increase has been driven by boys, up from 3.7% to 4.8%, while the proportion of severely obese girls has risen from 2.6% to 3.3%.

To be classified as severely obese, an individual must have a body mass index of 40 or more.

The figures did, however, reveal a decline in excess weight, overweight, obesity and severe obesity in Reception-age boys

The figures, released by Public Health England (PHE), are based on analysis of the annual National Child Measurement Programme – which captures the height and weight of over one million children in Reception (aged four to five years) and Year 6 (aged 10 to 11 years).

PHE also said the data showed children living in deprived areas were more likely to be obese, overweight or severely obese.

The Year 6 findings are likely to put food businesses under further pressure to reduce the sugar content of products, and follow the publication of the second chapter of the government’s Childhood Obesity Plan. Designed to help halve childhood obesity by 2030, key actions in the plan include mandatory calorie labelling on menus and restrictions on price promotions on foods high in fat, salt or sugar.

“The rise in severe obesity and widening health inequalities highlight why bold measures are needed to tackle this threat to our children’s health,” said PHE chief nutritionist Dr Alison Tedstone. “These trends are extremely worrying and have been decades in the making – reversing them will not happen overnight.”

The findings were particularly worrying as obesity has a negative impact on children in the short and the long term, said Bridget Benelam, nutrition communications manager at the British Nutrition Foundation (BNF).

“However, while addressing obesity and overweight in children, it’s important to remember that they are growing and developing, so having a balanced diet is key not only for a healthy weight, but to provide all the essential nutrients they need to be healthy.”

She added that the BNF’s National Diet and Nutrition Survey had shown 11 to 18-year-olds have the worst micronutrient intakes of any age group in the population.

“There is no easy way to address excess weight in children but sugar and calorie reduction in foods and drinks, making healthier choices easier for families, and encouraging healthy policies and education in schools are all things that can contribute to turning the tide of the current obesity epidemic.”