Why taxing 'junk food' to tackle obesity isn't as simple as it seems

Former prime minister Tony Blair has called for more taxes on junk food to tackle the UK’s obesity crisis. This includes extending sugar taxes beyond just soft drinks, as well as taxing food that is high in salt and fat. Blair also called for restrictions on advertising unhealthy food.

The former PM believes this is the only way to save the NHS. “We’ve got to shift from a service that’s treating people when they’re ill to a service that is focused on wellbeing, on prevention, on how people live more healthy lives,” he told The Times Health Commission.

But is it as simple as that? A levy on sugary drinks was introduced in the UK in 2018 which led to drinks makers reformulating their products so they contained less sugar. A year later, the British public was consuming less sugar. However, sugar consumption had been falling in Britain before the levy was introduced. Once this was factored into the analysis, there was no significant fall in sugar consumption.

Denmark experimented with a fat tax and it had similar underwhelming results. It was hailed as a world-leading public health policy when it was introduced in October 2011 but was abandoned 15 months later.

According to one survey, only 7% of Danes reduced the amount of butter, cream and cheese they bought. A different survey found that 80% did not change their food shopping habits at all.

However, whether or not levies on unhealthy food work is difficult to determine. Advocates for these programmes tend to highlight positive effects based on data modelling rather than actual changes in people’s weight and health. Detractors, on the other hand, quickly challenge such policies as being the enactment of the “nanny state”.

Where and what to tax?

Although the UK’s sugar tax led to drinks being reformulated to have less sugar, it also had some unintended consequences. For example, sugary drinks called slushies needed to have glycerol (E422) added to them to maintain their slush (artificial sweeteners failed to produce the required “slush”).

While this is safe for most older children and adults, the Food Standards Agency identified a possible risk of glycerol intoxication in smaller children and suggested sales should be restricted to children five years old and older.

Another unintended consequence is making the poor poorer by raising the price of food. If taxes or levies are extended beyond drinks and sugar to include all food high in fat, salt and sugar, the cost of this reformulation is likely to be passed on to the consumer.

With the current cost of living crisis, this is simply not acceptable to politicians or many of the public. If such levies are introduced, they need to be a smarter version of the soft drinks industry levy. It should drive food producers to change the food they produce, making less healthy ingredients cost more while making it more profitable to grow and supply healthier food.

What is ‘junk’ food?

The next challenge is to identify which food to tax.

Blair suggested “junk food”, which he defined as high in fat, salt and sugar - often called HFSS foods. It is these foods that can no longer be advertised on Transport for London sites.

This has been hailed as a success. These restrictions on advertising are estimated to have significantly decreased the average amount of HFSS foods households buy each week.

This data was then used to claim that this change reduced the number of people with obesity by 100,000. This claim has been heavily criticised. It is an estimate, and the change in the number of people who are overweight or obese linked to the advertising ban is unknown.

So, although there may be some merit in tackling advertising, it perhaps needs to be smarter and respond to modern and emerging trends in advertising strategies. The focus on out-of-home advertising, which is the Transport for London approach, does not look at how social media and online advertising linked to cookies and trackers can build a message for potential consumers. Challenging how advertisers link campaigns across media is probably more effective.

An alternative is to focus where advertising is permitted. For example, regulating billboards near schools so that they only show healthy messages may be a more effective solution.

This is before considering the potentially stigmatising language in calling food “junk” food, especially given the message is focused on helping poorer people. Perhaps this is why there has been a move to use terms such as “ultra-processed food”.

Both, however, are slightly subjective. The HFSS definition could include cheese and Greek yoghurt and therefore might suggest that these foods receive an advertising ban. Whereas a fast-food meal with water and carrot sticks – although these may be the least popular meal option – can still be advertised.

When promoting healthier dietary choices, we need to make options like vegetables attractive. This can be difficult for people on low incomes, who might avoid trying new food that might be rejected and wasted. Instead, go for family favourites which might be less healthy but will make sure everyone is full within their budget.

So what are the answers? Perhaps not top-down approaches, such as those proposed by Blair. An example of how our food system can be changed has been set out in the Birmingham Food System Strategy. This sets out how small local food businesses make healthier food widely available across the city, as well as provide employment in the city. This sets out a community-led approach that encourages a city-wide food supply that is healthy for people and the planet.

To solve a complex problem you need subtle and connected changes in many areas that are designed with and are acceptable to those with the most to gain, but who are struggling on low incomes.