It’s a curious paradox that as the Western world becomes more prosperous and its population lives longer, some of the most preventable health crises are rapidly escalating. One of the first and foremost among them: childhood obesity.

The stats make for alarming reading: one in three UK children are overweight or obese before they finish primary school. Of these, 40% will become obese adolescents. The vast majority of whom – 75-80% – will become obese adults at severely heightened risk of developing Type 2 diabetes and other health issues.

The causes of child obesity aren’t homogenous; hereditary, physiological, social and environmental factors can all play a role. But there’s no doubt that ever since the end of WWII in the West, and more recently in developing countries, there’s been a surplus of calories in the food we consume. As Susan Jebb, professor of Diet and Population Health at the University of Oxford put it this week, the situation in which food is readily available for most people has arrived in the blink of an eye in evolutionary terms.

Industry appears indifferent. Take Starbucks, for example, which pledged to slash added sugar in its drinks in alignment with the Government’s Childhood Obesity Plan. That didn’t stop them marketing a “short-sized” hot chocolate for kids with a whopping 20.1g of added sugar – more than the entire recommended daily limit for 4-6 year olds. Starbucks is by no means alone.

So how can we address the problem? If the corporate world is unable or unwilling to step up to the task, we’re left with two options: ‘hard’ measures (regulation), or ‘soft’ measures (promoting, assisting and allowing healthier choices).

There’s a strong case for the latter. By applying psychological insights, or ‘nudge theory’, we can encourage or guide behaviour without mandating or instructing. “’Nudging’ has been used by advertisers for decades,” says Dr Leah Avery, Head of Health Psychology at Changing Health. “That has contributed to an over-consuming society, and in turn, the obesity epidemic. In a sense, we need ‘counter-nudges’ to combat those used by advertisers.”

Even the subtlest of nudges can be highly effective in facilitating positive behaviour change. In New Mexico, USA, a simple change in the design of a shopping trolley was shown to help people make better decisions about the food they buy. Researchers marked a line with yellow duct tape across the width of the trolley, and added a sign asking shoppers to place fruit and vegetables in front of the line and everything else behind it. The result was a 102% increase in sales of fruit & vegetables (at no loss of profitability to the retailer).

In Iceland, LazyTown, a popular childrens’ TV show, features a healthy superhero motivating children to eat healthily and be active. In partnership with the Icelandic Government, children aged 4-7 were sent a LazyTown “energy contract”, signed with their parents, in which they were rewarded for eating healthily, going to bed early and being active. One supermarket chain rebranded all its fruit and vegetables “Sports Candy” – LazyTown’s name for healthy food – and saw a consequent 22% increase in sales. Since LazyTown hit the airwaves in 1996, Iceland has become one of the only countries in the world in which child obesity levels have fallen.

There’s promise closer to home too. A partnership between LazyTown and the UK Nudge Unit led to the launch of the Change4Life programme, Public Health England’s flagship initiative for preventing childhood obesity. This year’s Change4Life campaign, encouraging parents to look for ‘100 calorie snacks, 2 a day max’ provides parents with money-off vouchers for healthier snack options including malt loaf, lower-sugar fromage frais, and drinks with no added sugar. A survey of 1001 mums who used the Change4Life Sugar Smart app found 96% of those with children aged 5-11 had reduced their families’ sugar intake.

Tesco, the chain which first embraced the behavioural insights approach by removing sweets and chocolate from its checkout aisles, has this month devised another way to nudge people into making healthier choices. Its ‘little swaps’ basket comparison will be displayed at the front of stores to highlight lower sat fat, salt and sugar alternatives to the most popular childrens’ products. The comparison busts the myth that healthier choices cost more too.

Image: Tesco PLC

Nudges alone, however, will not suffice. Government policy must also play a role. “Regulation is a powerful influence on behaviour,” says Stephen Greene, Past President International Society of Pediatric and Adolescent Diabetes. “Just as Government was central to the banning of smoking indoors in public places, the supply of food to children in schools, labelling, the use of unhealthy products – they should all be looked at both locally and centrally to influence what’s going on.”

“Legislation, nudges and group and individualised interventions are all needed to tackle the public health challenges we’re facing,” agrees Dr Avery. “Efforts on these fronts should be co-ordinated and robustly evaluated.”

Professor Greene adds that we need to see some real cultural shifts in how industry produces and distributes food, and how consumers eat it. Perhaps that’s not too far out of sight. “In the same way one dinner lady inspired Jamie Oliver to change attitudes to food in schools across the country, we’ll see a shift in attitudes to sugar over a generation. The understanding is dawning that sugar has played such a big role in childhood obesity.”

In a world in which the next generation is set, for the first time, to be less healthy than the last, that understanding can’t come soon enough.