The Royal Society for Public Health (RSPH) report calls for a ‘whole school' approach to physical activity and warns without action, over four in 10 children aged 10 and over could be overweight by 2035.

William Roberts chief executive, Royal Society for Public Health, said: ‘As a nation we're failing the test on childhood obesity. Our projections show that we are heading in the wrong direction on obesity, with children in some of the most deprived areas set to be worst affected.

‘The habits we form as children last a lifetime. Making physical activity the default in schools will go along away in helping to build a healthier future. Rather than seeing physical activity as something that happens for two hours a week in PE, we need to see it as an integral part of the whole curriculum.'

The report highlights a range of actions, including such as new Ofsted reporting based on how schools promote children's wellbeing, which would include how well they encourage physical activity.

Additionally, it argues for changes to the PE and spremium that would allow schools to spend funding ringfenced for PE on measures that could increase physical activity across the school day.

RSPH is also calling on Department for Culture, Media, and Sport to lead on a Youth Physical Activity Strategy. This would bring together schools, the public sector, sports governing bodies, the gym industry, and others, to create a whole systems approach to youth physical activity.

Cllr David Fothergill, chairman of the Local Government Association's Community Wellbeing Board, said: ‘The Government must work with councils and others to turbo charge the efforts to tackle this ticking health time bomb, so we can collectively tackle sedentary lifestyles and boost physical activity. 

‘Access to healthy, nutritious food is a huge challenge for families in our most disadvantaged communities, particularly amidst the ongoing rise in the cost-of-living. 

‘To effectively tackle obesity, councils need funding to provide targeted support to those who need it the most. Money raised from the soft drinks industry levy should also be reinvested in other council-run programmes, including healthy eating programmes and active play and physical exercise schemes. 

‘It is vital that councils are adequately funded through the public health grant to provide the frontline services that tackle obesity, so we were concerned the Spending Review once again overlooked public health funding. Investment in councils' public health services now will reap benefits for everyone longer-term and help improve the life chances of the next generation.'

A Government spokesperson said: ‘Through our Plan for Change, this Government is determined to give every child the best start in life, which includes creating the healthiest generation of children in our history.

‘That is why we are acting quickly with experts across the sector to revise the School Food Standards, so every school is supported with the latest nutrition guidance. We are also considering how best to build physical activity into the lives of children and adults as part of our mission to boost the nation's health.

‘More widely, we are urgently tackling the childhood obesity crisis by shifting our focus from treatment to prevention, including by limiting school children's access to fast food and cracking down on junk food advertising.'