Britain is in the grip of an epidemic. In the UK two-thirds of adults and a third of children are already overweight or obese, and without action this could rise to almost nine in 10 adults and two-thirds of children by 2050.

This trend has a severe impact on the health of individuals, increasing the risk of diabetes, cancer and heart and liver disease. The eminent scientists who spent two years studying the long-term effects of obesity predict a sevenfold increase in direct healthcare costs and that 60% of men, 50% of women and 25% of children will be obese by 2050 if nothing is done to tackle current trends.

The cost will be felt by every single part of society, not just in headline financial or health terms but in very personal ways, affecting the lives and opportunities of millions of people. The core of the problem is simple – we eat too much and undertake too little physical activity. The solution is more complex.

This imbalance is ultimately the result of what the scientists call an “obesogenic environment”, from the nature of the food that we eat to the built environment and the way our children lead their lives: it is harder to avoid obesity. In short, modern life is contributing to making us overweight.

It was the scientists in their Foresight report who said society is facing a public health problem that is comparable to climate change. Failure to act now will lead to serious adverse consequences in a few decades, and any delay raises the real possibility that reversal of these trends may cease to be an option.

This week we will publish a cross-government strategy on obesity. Having been at least 30 years in the making, the epidemic will not be halted overnight. The strategy is the first stage of the government’s response to the Foresight report and will be followed by an annual report that assesses progress, looks at the latest evidence and trends and makes recommendations for further action. A panel of experts will assist the government with input from a new public health obesity observatory that will develop our understanding of what changes behaviour.

The strategy will focus on five areas: healthy children, promoting healthier food choices, building physical activity into our daily lives, creating incentives for better health, and personalised information and care for people already overweight or obese.

It will build upon the measures already taken on food labelling, restrictions on advertising to children and healthy school meals. Ed Balls’s Children’s Plan sets out the steps we have taken and will take to increase physical activity levels in schools and improve the nutritional content of school food even further.

Obviously, government action alone is not enough. We will succeed only if the problem is recognised, owned and addressed in every part of society – in particular it will require personal responsibility and action among communities, teachers, clinicians, industry and local and national government.

Some will characterise any attempt by government to tackle this problem as unnecessary interference with individual choice. The fact is that people worry more about a neglectful state than a nanny state.

It is not the government’s job to hector or lecture, but it is our duty to give people clear and transparent information, and to help and support them in their endeavours to make sure they and their children can pursue a healthy lifestyle.

Making sure people have the right information is critical. Whether it is the importance of breastfeeding, the impact of diet on health or better food labelling, it is essential that people can make an informed choice about their diet and lifestyle. Government and industry have a duty to do more to make sure the food we buy is healthier, and to ensure clear and consistent information.

We also need to do more to give people the opportunity to build activity into their daily lives. The fabric of our urban and rural spaces needs to change to encourage healthy living. That’s why I want to establish a fund that will pioneer fresh approaches in new and existing towns to promote physical activity.

These “healthy towns” will build on a successful model developed in France and will combine infrastructure improvements – such as better cycle routes and higher-quality parks – with community programmes that promote healthy eating and activity.

Hazel Blears, the communities secretary, and I will also look at how the planning system can help all areas by making decisions that promote physical activity, with better use of the regulations that enable local authorities to limit the spread of fast-food outlets, especially near parks and schools.

As the prime minister set out in his speech at King’s College London, the NHS also needs to do more to offer a personalised service that is as focused on predict and prevent as diagnose and cure. The NHS has a central role in helping people who are overweight or obese to achieve real sustained weight loss.

The rising tide of overweight and obese people is the most significant public and personal health challenge facing our society. With concerted action across government and with wide institutional support aligned to personal responsibility, I am confident we can do what no other country has yet done and reverse the obesity trend.

Alan Johnson is secretary of state for health

Times Recommends

• Fantasy world fuelled by sex, drink and drugs
• In short, the story is growing on us again
• A literary feast that I can’t wolf down