While education remains a crucial factor in ensuring people maintain healthy diets, our latest research shows this alone is not enough: healthy eating is too difficult for typical British families. Too many factors – including an imbalance in the price of healthy and unhealthy food – push our behaviour in the wrong direction. Voluntary industry initiatives have not achieved enough and our food system needs a major overhaul to make healthy eating easier for everyone. The proposed, and often misunderstood, sugar tax has a role to play in this.

First, what would be taxed? After all, sugar appears in many foods, including many that are good for us, like fruit. The calls for a sugar tax are actually very specific: it should be a tax on soft drinks with added sugar – the largest source of sugar in our children’s diets.

The reasons for a tax on sugary drinks stems from solid evidence. Last summer the government’s independent scientific advisory committee on nutrition concluded that sugary drinks should be “minimised” in our diets. It is very rare for this committee to make a recommendation such as this, and they are normally reserved for foods with poisonous effects. The committee drew this conclusion after reviewing thousands of studies and finding that consumption of sugary drinks is directly linked to type 2 diabetes.

Type 2 diabetes now affects more than one in 20 people in the UK. It is a condition that many children are developing, and which causes nerve damage, blindness, kidney failure, strokes and can result in amputations. But it’s not just diabetes, tooth decay now affects one third of five-year-olds in England, and is the most common reason for hospital admissions among children aged between five and nine.

Given the strength of the scientific evidence it would be irresponsible not to find ways to lessen the consumption of sugary drinks among children. We have strict regulations, for example, controlling the safety of toys, or the use of car seats. Why is the food and drink our children consume on daily basis treated differently?

How would a tax work? It would probably be applied as an excise tax on a per volume or unit basis. The more you buy, the more you pay. Where the additional government revenue goes is an important issue. Spending it on a range of measures to tackle diet-related disease could double the impact of the tax. Given that the health consequences of poor diets have a disproportionate affect on those on lower incomes, a sugar tax would be progressive if its revenue were used to close our nation’s stark health inequalities.

There’s no doubt the revenue is urgently needed. Local authorities’ public health budgets were cut by £200m in 2015. The NHS currently spends about 10% of its budget on diabetes treatment (and estimated £10bn a year) and this is expected to rise to 17% in the next 20 years.

But would a sugar tax actually reduce consumption? Research published last month in the British Medical Journal shows that it does. The much-cited study, conducted in 53 cities in Mexico, measured the impact of the introduction of a 10% tax on sugary drinks and recorded an instant result. Purchases fell by 6% initially and by 12% after one year.

The majority of people bought plain bottled water instead, though untaxed non-sugar sweetened soft drinks provide consumers with healthier, cheaper alternatives. In a separate, systematic review of hundreds of academic papers, Public Health England concluded that price increases in the UK of between 10-20% would help lower purchases of sugar sweetened drinks, with higher increases having the greatest effect.

Would this solve the obesity problem, which now affects 20% of our 11-year-olds? Of course not, but it would certainly help. The global obesity crisis is far more complex than sugar alone. Food Foundation research shows that almost half of the diet of a typical primary school child is made up of foods which are high in fat, sugar and/or salt. The research also shows that calorie for calorie, healthy foods in Britain are three times more expensive than unhealthy foods. The balance of prices in our shopping basket is wrong and this is compounded by an environment – of adverts, promotions and ubiquitous fast food outlets – which makes it incredibly difficult to maintain a healthy diet.

A raft of cross-governmental measures designed to make healthy eating easier for people in Britain is desperately needed. Evidence shows that the rebalancing of prices through a sugar tax would be a step in the right direction.

This article was amended on 4 February to correct a subbing error. More than one in 20 people in the UK has type 2 diabetes, not one in 16 as the original stated.