The boss of Unilever, one of the world’s biggest food manufacturers, has warned that a sugar tax will not solve Britain’s obesity crisis and said it is “too simple” as a proposal.

Amid a growing clamour from politicians and campaign groups for a sugar tax, Paul Polman said there was little evidence that introducing a levy on food and drink with a high sugar content would help tackle obesity.

Unilever makes some of Britain’s most popular snacks, including Magnum, Ben & Jerry’s, and Cornetto ice-creams.

The government is considering a sugar tax – particularly on fizzy drinks – as part of a national strategy to tackle childhood obesity, which is scheduled to be unveiled next month.

The NHS already plans to impose its own sugar tax in hospitals by charging extra for high-sugar snacks and drinks sold in its cafes and vending machines.

An estimated two-thirds of adults in Britain are now overweight and bad diet has overtaken smoking as the biggest single cause of lifestyle-linked avoidable illnesses. There are 4 million diabetic patients in Britain.

However, the chief executive said a sugar tax was not the “holy grail” and insisted that the countries that have introduced it, such as Mexico, are not seeing obvious benefits.

Instead, Unilever has said it is tackling the problem by reworking its own products. The company has pledged that all its single-serve ice-creams will contain 250 calories or fewer by this spring in Britain as part of its “sustainable living plan”. To achieve this, Unilever is cutting the size of its ice-creams, including Magnum, Ben & Jerry’s and Cornetto, some by up to a third.

Polman said: “A simple sugar tax would to me be too simple a solution. It would be an easy political solution in the short term, but it would be too simple a solution.

“You need to attack this holistically with a lot of things. Just doing sugar alone has not proven to be the holy grail. It goes way beyond just putting a tax on sugar. Countries like Mexico and others that have done that are actually starting to see that as well.”

It is understood that a sugar tax is not in David Cameron’s current plans to tackle obesity, although, in the face of growing pressure, the prime minister has not ruled it out. Instead, he is considering forcing fizzy drinkmakers to reduce the sugar content of their products by 20%, banning the advertising of sugary products to children, and stopping 2-for-1 promotions on unhealthy goods

The food and drink industry has been in talks with the government about a national obesity strategy, but it is against demands for an arbitrary reduction in sugar content across the board. Companies such as Coca-Cola have suggested they aim to cut 20% of the sugar in the existing diet of a consumer by a combination of reformulating their products and promoting low-sugar alternatives such as Diet Coke.

Polman said the situation in Mexico proved the UK government needed a multi-faceted approach.

“There have been some improvements, but they have had many other things going on as well,” he said. “It is difficult to isolate but it’s not the improvement yet that they are looking for either. It’s not the holy grail.

“In essence, there is nothing wrong with [sugar], it depends on how your diet is. In some products it makes more sense, in others not. I personally am very mindful of my sugar intake. But I don’t need a tax for that, nor do poor people need a tax for that. Poor people need to be helped not being poor, that’s probably a bigger thing than anything else.

“There is a clear divide in society as where obesity occurs – so we have to work on the inequality, we have attack the issues on food security.

“Look at the US now – 80% of the growth in food is in healthier products. There is no tax on that, it’s totally driven by change in consumer habits. You are now starting to see the same here in the UK.”

However, Sarah Wollaston, chair of the House of Commons health committee, said that not introducing a tax on sugary drinks would “miss an important opportunity”.

Wollaston, a Tory MP and a former GP, said: “The childhood obesity strategy needs to tackle the problem from every angle, but to leave out a sugary drinks tax would miss an important opportunity to tackle the single biggest contributor of the sugar in teenagers’ diets. There is compelling evidence it would work and do so quickly.

“We also need to include reformulation, too, but, as we have seen with reducing salt levels in our food, that can take years. It could happen in parallel with a sugary drinks tax.

“As with the successful plastic bag levy, the whole point of a sugary drinks tax is that no one needs to pay it at all. Any proceeds could and should go towards children’s health projects like sport or teaching cookery skills, for example.

“We cannot keep ignoring the harm, widening health inequality and cost of childhood obesity both to individuals and wider society.”

David Haslam, chairman of the National Obesity Forum (NOF), said: “Currently NOF are calling for a sugar tax on sugar sweetened beverages [SSBs], but a call for a tax for sugary foods is just around the corner.

“The Mexican example is interesting and revolutionary, and despite cultural, economical and political pressures, it seems to be promising. But the UK is not Mexico - the UK has drinkable tap water as an alternative to SSBs, and is not under the monopoly of certain drinks companies, and is at the clinical forefront of sugar reduction policies. Taxing ice-cream is a logical next step, not a random leap into the darkness.”