On top of that you were limited to one egg a week and just a handful of sugar.

But that's the diet that was tested by two nutritionists in a unique experiment devised during the early days of the Second World War.

And arguably it was healthier than the average diet today.

In the late 1930s Britain imported 70% of its food from overseas, often relying on shipping routes vulnerable to German U-boat attack.

By January 1940 supplies were so scarce that food rationing was introduced.

But the government was fearful that the country would be completely cut off by the U-boats and would have to keep its population fed and healthy using only food produced in the UK.

Before the war, nutritionists Elsie Widdeson and Robert McCants had developed a set of food tables looking at the nutritional value of meat, fish, fruit, bread, sweets and dairy.

They were no strangers to self-experimentation, even going so far as injecting themselves with iron and strontium lactate to test how they were processed by the body, an act that left them rolling around the floor in misery.

Together they calculated the amount of food that would be available if Germany was able to cut off British ports and then divided it into a weekly allowance.

The rations were meagre to say the least.

As well as that solitary egg and 140 grams of sugar a week, you could only have 450 grams of meat and fish combined, 113 grams of fats, the same of cheese, 170 grams of fruit, that's around two apples, and a quarter of a pint of milk a day.

British grown vegetables and bread weren't restricted, but the rationed foods represented less than half and in some cases less than a third of the average weekly consumption in Britain before the war began.

It was enough to survive, but would it be enough to maintain fitness in the long term?

Widdeson and McCants put their bodies on the line to find out.

In January 1940 they headed to the Lake District where they tested the diet whilst on a rigorous regime of cycling and confirming that health and fitness could be maintained under this severe diet.

They did however note a remarkable increase in flatulence.

The extreme diet Widdeson and McCants tested wasn't actually needed in the end because sufficient imports from the US managed to get to Britain throughout the war.

But it proved that the population would be able to manage on it and their findings were a key influence behind the government's decision to leave bread and The rationing that was introduced delivered around 3,000 calories a person a day with some manual labourers receiving extra.

Nevertheless the diet was often bland.

Thanks to the Ministry of Food, households were inspired to create such culinary delights as a Wilton pie, a mix of swede, turnip and cauliflower covered with shortcrust pastry or mashed potato.

It's fair to say it wasn't much loved.

Blandness wasn't the only issue.

In further studies Widdeson and McCants realised that people wouldn't get as much calcium as they needed if milk and cheese were to be severely rationed.

This might prove disastrous as a lack of calcium can lead to the bone disease rickets.

In 1941 based on their advice the government brought in the fortification of bread with calcium in the form of powdered chalk.

This ensured people got enough of the mineral in their diet despite the restrictions on dairy.

Food rationing lasted until 1954 but even after it ended bread continued to be fortified with calcium.

It's still the case in the UK today if you're wondering who to thank for your healthy bones.

Whilst rationing wasn't easy for Britain it got the nation through a wartime crisis in pretty good shape and arguably even McCants' and Widdeson's extreme diet was healthier than our average diet today so dominated by high and high salt foods.

The pair continued to demonstrate that they were prepared to go the extra mile in the name of science.

Widdeson famously found a dead baby seal on a beach in Scotland which she drove back to Cambridge in the boot of her car in order to further her research into body fat composition.

Widdeson's and McCants' legacies live on and not just in terms of nutrition.

When she died Widdeson left money to enable female scientists to balance their lives.

She was the first generation of pioneering women to help solve our complex scientific problems today.