When you have a global pandemic of disease, telling people to take personal responsibility for it is unlikely to be the answer. Faced with a time bomb of childhood obesity in the United Kingdom capital, London’s Mayor, Sadiq Khan, has proposed banning adverts for junk food and drink from tubes and buses. But for the most part, arguments about obesity remain stuck on a loop. It was MPs’ turn to hear them again this week when the health select committee took evidence from food and advertising lobbyists, academics and health specialists.

Susan Jebb, professor of diet and population health at Oxford University, may have been surprised to see what she billed as a “rather silly little tip”, of the take-personal-responsibility sort — pay for your fuel at the pump to avoid the sugary, fatty snacks at the checkout — elevated to front-page news.

Actually, she was calling for a whole range of mandatory measures to counter the way companies bombard us with food and drink at every opportunity — measures of which a junk food advertising ban could be one. Even petrol stations selling fast food and confectionary are now part of an environment that has become obesogenic, constantly prompting us to do the unhealthy thing.

Recognising that our environment engenders obesity is crucial to understanding why so many people around the world are now dangerously overweight. When populations as a whole are affected, with the lower socioeconomic groups more affected, it is clear that obesity has social determinants. It also becomes clear that it requires the government to reshape the environment. Although we can exercise a thousand rebellions individually, none of us can change the landscape on our own.

Boyd Swinburn, the New Zealand public health expert who coined the phrase obesogenic environment, observed that it was not something wrong within the body that determined the high rates of diabetes and obesity among previously healthy Native American populations corralled into reservations, but their bodies’ normal physiological response to an abnormal environment.

The environment is obesogenic when energy-dense, but nutrient-light foods are cheaper than fresh, healthy ones; when they are promoted with discounts encouraging you to buy three rather than one; when alcohol is sold as a loss leader; when sweets are placed at checkouts not just in grocery stores but many non-food shops too; when junk food outlets dominate your high street; and when advertising insidiously steers your purchasing in the wrong direction.

Obesogenic environment

It’s obesogenic when cars take precedence over safety for pedestrians and cyclists, so parents fear to let their children walk, and when screen time pushes out exercise outdoors.

Food and drink manufacturers and advertising executives don’t like the idea of an obesogenic environment because it throws responsibility back on to policymakers and regulators, and that means restricting their activities.

Last week, we saw them turning cartwheels to do themselves down. Advertising costing billions has only a modest impact on people’s choices, they told MPs — as they will no doubt tell the London mayor in the months ahead as they attempt to water down his plan.

Prof Jebb explained that obesity is often caused by small, incremental excesses of energy intake, and many small interventions will be needed to change the environment. These range from preserving playing fields and parks to planning rules that favour physical activity and restrict fast food outlets. They include tighter controls on the advertising and promotion of junk food, and the closing of loopholes that allow social media to bypass regulations imposed on other media. We may need tax disincentives — such as the sugary drinks levy — on over-processed unhealthy foods, and new incentives to grow healthier produce.

Doing nothing is not an option. The latest figures show that 66 per cent of men and 57 per cent of women in the UK are overweight or obese. Full-blown obesity affects more than a quarter of the population, with one in five children obese by the age of 10. Those in lower socioeconomic groups are twice as likely to suffer from obesity as those in more affluent groups, and that health gap keeps growing.

— Guardian News & Media Ltd

Felicity Lawrence is a special correspondent for the Guardian.