Do sin taxes work?

Boris Johnson has pledged to review the UK’s sugar tax – a “sin tax” – and focus more on encouraging people to exercise.

– What are sin taxes?

Sin taxes include levies on unhealthy food, drink, alcohol and cigarettes. Mr Johnson’s team said on Wednesday that he is referring to taxes on unhealthy food and drink, such as the proposed tax on milkshakes.

– How are my drinks affected?

The levy is applied to manufacturers. Whether they pass it on to consumers or not is up to them.

Drinks with more than 8g of sugar per 100ml have a tax rate equivalent to 24p per litre.

Those containing 5g-8g per 100ml have a tax rate of 18p per litre.

Pure fruit juices are exempt, as are those with a high milk content, as they contain calcium.

– Is the UK alone on this?

No. Hungary, France, Mexico, Chile, Barbados and parts of California also have a sugar tax for sugary drinks. Some also have a tax on foods that are high in sugar and salt.

– Are such taxes effective?

Evidence is mixed depending on which item of food or drink is looked at, but, generally, health experts believe they lead to a change in habits.

The UK tax on sugary drinks is said to have taken 90 million kg of sugar out of the nation’s diet on the first day it was introduced.

A UK modelling study estimated that a 40% reduction in added sugars in drinks over five years would cut the number of obese adults by roughly half a million and new cases of Type 2 diabetes by around 300,000.

In Mexico, the sugar tax led to a 6%-12% reduction in the number of sugary beverages bought.

Meanwhile, in Berkeley, California, there was a 21% decrease in the consumption of sugar-sweetened beverages and a 63% increase in the consumption of water in the city’s low-income neighbourhoods.

– What’s next?

England’s Chief Medical Officer is looking at taxing all unhealthy foods in a bid to tackle childhood obesity.

A report by Professor Dame Sally Davies is due in September, commissioned by Health Secretary Matt Hancock.