Boris Johnso, who is the favourite to succeed Theresa May as Prime Minister in three weeks, has vowed to challenge the ‘nanny state’ by pledging a review of evidence around ‘sin taxes’ on unhealthy foods and beverages.

The affected items would include the current sugar levy on the soft drinks industry, which has been proposed to be extended to sugary milk-based drinks, such as milkshakes.

Defending his position, Mr Johnson said: “The recent proposal for a tax on milkshakes seems to me to clobber those who can least afford it.

“If we want people to lose weight and live healthier lifestyles, we should encourage people to walk, cycle and generally do more exercise.

“Rather than just taxing people more, we should look at how effective the so-called ‘sin taxes’ really are, and if they actually change behaviour.

“Once we leave the EU on 31 October, we will have a historic opportunity to change the way politics is done in this country. A good way to start would be basing tax policy on clear evidence.”

Health Secretary Matt Hancock, who is now a key supporter of Mr Johnson�s leadership bid, had previously pledged an extension to the sugar tax. However, he has also welcomed the plans to review the effectiveness of the current sugar tax as well as any “future levies in this area”.

Former Health Secretary, Jeremy Hunt, who is also running for PM with his own leadership bid, has criticised Mr Johnson�s position, saying: “I’m totally confused about what Boris’s policy is on this because he’s saying he doesn’t want these ‘sin taxes’.

“But he’s got Matt Hancock, the health secretary, on his team who strongly supports them. So I think consistency really does matter.

“We have an obesity epidemic, we have the second highest number of obese young people anywhere in Europe and we do need to have a solution to this.

“So the people who want to scrap these taxes need to say what is their plan.”

The sugar tax has at least been effective in convincing soft drink manufacturers to reformulate some of their products. Chief Executive Officer of Cancer Research UK, Michelle Mitchell, notes that: “the Treasury’s own analysis showed the tax on sugary drinks took 90 million kg of sugar out of the nation’s diet on day one.

“Physical activity is one way to lose weight but the government also has a big role to play if we are to significantly reduce obesity levels.”

Issues with taxing sugary soft drinks have been raised by some people with type 1 diabetes, as reformulations may in some cases make it harder to get a quick dose of sugar and treat hypoglycemia.

The concept of a sugar tax has previously received backing from the World Health Organisation (WHO), who published a supportive report back in 2016, two years before the introduction of the UK sugar tax.

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