Families should eat as they did in the 1950s to avoid obesity, according to report on modern diets.

Portion sizes have ballooned in the last few decades - with people filling their plates to the brim and cleaning them of every last morsel.

British retailers are selling food in bigger and bigger packages - with the average supermarket pizza increasing from 200g to more than 250g in the last two decades alone.

Leading health scientists at Cambridge and Oxford universities warned today that this trend needs to be urgently reversed in order to tackle Britain’s obesity crisis.

And they advise that people eat off smaller plates to help moderate their diets.

Portion sizes have ballooned in the last few decades and we should revert to those served in the 1950s to combat the obesity crisis, experts claim

The authors of a new report in the British Medical Journal have cited figures which show that a range of everyday supermarket products have increased in size over the last 20 years. Pies, muffins, bagels, pizzas and packets of crisps are sold in larger packets than they were in the 1990s

The report's authors also advise a series of anti-obesity measures, such as eating off smaller plates. ‘Reducing portion sizes across the whole diet to realise large reductions in consumption may mean reverting to sizes of portions and tableware similar to those in the 1950s,’ they wrote

The authors, writing in the British Medical Journal, cited figures which show that a range of everyday supermarket products have increased in size over the last 20 years.

Pies, muffins, bagels, pizzas and packets of crisps are sold in larger packets than they were in the 1990s.

But the authors, led by Professor Theresa Marteau of Cambridge University, warned that people need to go back even further - to the 1950s when some food was still rationed - to really see their health improve.

‘Reducing portion sizes across the whole diet to realise large reductions in consumption may mean reverting to sizes of portions and tableware similar to those in the 1950s,’ they wrote.

Little data exists for average diets and portion sizes in post-war Britain - but the experts predict that consumption of energy-dense foods has more than doubled since then.

The Government voluntary agreement with food manufacturers - the so-called ‘Responsibility Deal’ - involves a mere 5 per cent reduction in calories, nowhere near the 50 per cent needed to get back to 1950s diets.

It research was published last night after Simon Stevens, chief executive of NHS England, warned that childhood obesity was a real ‘threat’ to the country’s long-term health.

Addressing the Chief Nursing Officer for England’s annual conference, Mr Stevens said the NHS had a ‘crucial’ role in helping lead a national debate on the issue.

He said: ‘We can help change the tide of opinion in this country.

‘We have to take a more assertive stance particularly on junk food, advertising and marketing of food aimed at children and sugar.’

Little data exists for average diets and portion sizes in the 1950s - but the experts predict that consumption of energy-dense foods has more than doubled since then

PORTION SIZES BY NUMBERS 1,233 Percentage increase of size of a chocolate bar since early 1900s 223 Percentage increase of size of a burger since the 1950s 500 Percentage increase of size of a fountain soda since the 1950s 4.56 Increase in size of restaurant portion compared to the 1950s 28 Increase in number of pounds of average weight of a man since the 1960s 24.5 Increase in number of pounds of average weight of a woman since the 1960s Advertisement

The new BMJ report summarises the most conclusive evidence to date on portion sizes, packaging, and tableware.

The authors calculated that simply reducing the size of a plate or bowl reduces food intake by 159 calories a day - a 10 per cent change for a British adult.

If the same approach is applied to all food and drink consumption - with smaller food packaging in supermarkets and sandwich shops, smaller bottles or glasses in bars and smaller portions in restaurants - overall calorie intake could be reduced by up to 16 per cent, they said.

People tend to fill their plate when they sit down for a meal - and do not stop eating until their plate is clean.

By using smaller tableware, they will put less food on their plate in the first place.

The team, who analysed 61 separate studies involving 6,711 participants, also called for retailers to stop discounting food sold in larger quantities.

Professor John Ashton, president of the Faculty of Public Health, last night said that if every family reduced their intake just slightly it would have a dramatic impact on the population’s health.

‘A 10 per cent reduction in food intake may not seem like much - but multiplied by 60million people it would have a really big impact on diabetes and obesity.’

But he admitted it would not be easy to make such changes.

‘People now eat confectionary, for example, all the time,’ he said. ‘How do we get back to the situation where confectionary is a treat rather than an everyday item?’

THE GRAPHIC THAT REVEALS JUST HOW MUCH PORTIONS HAVE INCREASED A startling infographic produced by the US Government in 2012 highlighted just how out of control the country's meal servings are - with the average restaurant portion more than four times as big as it was in the 1950s. The image, created by the Centers for Disease Control and Prevention, shows a cup of fountain soda is now six times as large, while burgers and a portion of fries have both tripled in size. Also horrifying is how a chocolate bar is now a staggering 1,233 per cent larger than it was in the early 1900s, according to the CDC's its The New (Ab)normal campaign. It is unsurprising then, that US adults are 26 pounds heavier today than they were in the 1950s; women have on average increased by 24.5 pounds while men have expanded by 28 pounds. Out of control: The Centers for Disease Control and Prevention (CDC) released this graphic in 2012 as part of its The New (Ab)normal campaign. It shows just how meal sizes have increased in the past 60 years The CDC released the graphic to raise awareness of how portion sizes are growing - and how they could unknowingly be posing a health hazard to families dining out. Its research also suggests the trend has also reached grocery stores and vending machines, 'where an individual bag of chips can easily feed more than one'. The CDC's resources suggest that research shows people unintentionally consumer more calories when faced with larger portions, leading to an overdose of calories. It suggests: 'If we want to eat healthy, there are a few things we can do for ourselves. 'Order the smaller meals on the menu, split a meal with a friend, or, eat half and take the rest home. We can also ask the managers at our favorite restaurants to offer smaller meals.' The graphic shows how the average cup of soda has jumped from seven ounces to 42 ounces over the past 60 years - a staggering 783 per cent increase. A hamburger has grown from 3.9 ounces to 12 ounces, while a basket of fries was 2.4 ounces but now told 6.7 ounces. The campaign comes as the extent of the impact of obesity on the nation is becoming apparent after reports of how businesses, governments and individuals are coming to grips with the costs of the extra pounds. Advertisement