A snack tax of 20% on biscuits, cakes and sweets would have “a huge impact” on obesity levels in the UK and be more effective than the current levy on colas and other sugary drinks, say experts.

But the idea may struggle to get past the current government. Boris Johnson took a stand against “sin stealth taxes” in July, ordering a review and opposing plans to extend the sugary drinks tax to milkshakes, which he said “seems to me to clobber those who can least afford it”.

Researchers writing in the British Medical Journal say the UK’s love of sweet snacks means it should consider taxing food as well as drinks, which would lead to a drop in sales especially among families where obesity is a problem and incomes are low.

Dr Pauline Scheelbeek from the London School of Hygiene and Tropical Medicine, the lead author of the study, said a snack tax could cut obesity in the UK population from about 28% to about 25%. “That is, on a population level, a huge impact,” she said.

Q&A Why is sugar bad for you? Show Hide Eating too much sugar contributes to people having too many calories during the day, which can lead to weight gain. Being overweight increases the risk of health problems such as heart diseases, type 2 diabetes, and some forms of cancer. Sugar is also one of the main causes of tooth decay. The NHS advises that most adults and children in the UK eat too much of a type of sugar called 'free sugars'. These are the sugars added to food and drinks, found in biscuits, chocolate, breakfast cereals and fizzy drinks. But they are also found naturally in honey and unsweetened fruit juices. The UK government’s recommendation is that these 'free sugars' should not make up more than 5% of the calories you have every day. That is still quite a lot of sugar - it equates to seven sugar cubes worth for an adult. But bear in mind that one can of a fizzy drink can include the equivalent of 9 cubes of sugar. Children under 4 should avoid all sugar-sweetened drinks and food with added 'free sugars' in it. Martin Belam



In some countries, sugar intake is mostly from drinks, but the UK is keener on sweets and cakes. The research found that for all income groups combined, increasing the price of biscuits, cakes, chocolates and sweets by 20% would reduce annual average energy intake by about 8,900 calories, leading to an average weight loss of 1.3kg over one year. The effect would be greater among the lowest income families, where obesity levels are highest.

In contrast, a similar price increase on sugary drinks would result in an average weight loss of 203g over one year.

The impact would be greatest on the lowest income groups, leading some critics to call it a regressive tax that would hit the poorest. However, type 2 diabetes, heart attacks and strokes caused by obesity also affect the poorest most, said Scheelbeek.

“The burden of non-communicable diseases by itself is regressive,” she said. “The health impact is therefore progressive for people who consume large amounts of these products.

“We also saw that low income households have the strongest response to price changes. They won’t necessarily pay these taxes – they will cut these products out.”

A subsidy for fruit and vegetables would benefit the most affluent, who eat more of them and would “raise some ethical concerns”, she said.

Co-author Susan Jebb, professor of diet and population health at Oxford University and a former government adviser, argues that we need a more open-minded approach to what might work in the fight against obesity than Johnson’s “instinctive” rejection of sin taxes.

Many drinks companies have cut sugar from their products or use sweeteners instead, but that sort of reformulation is much harder in foods that need sugar for other reasons, such as to raise cakes or provide texture. Low-sugar confectionery is particularly unlikely to be popular.

“The only real option to cut sugar is for people to eat less. Previous efforts to encourage smaller portions have decreased the size of individual bars of chocolate, but coincided with a growth of so-called ‘sharing bags’ with no evidence of any substantive decrease in overall consumption. It’s time for a new approach,” Jebb writes in a commentary with Theresa Marteau from Cambridge University.

Fiona Sing of the World Cancer Research Fund said: “The idea of a ‘snack tax’ is very interesting and could be the start of some exciting developments in nutrition and health policy. There is already clear evidence from around the world that taxes are effective, such as in Mexico and Berkeley. So we welcome further research into other taxes on foods high in fat, salt and sugar.”