The 'Robin Hood' generation did not go in for refined sugar

Their low-fat, vegetable-rich diet - washed down by weak ale - was far better for the heart than today's starchy, processed foods, one GP says.

And while they consumed more they burnt off calories in a workout of 12 hours' labour, Dr Roger Henderson concludes.

But the Shropshire GP accepts that life for even prosperous peasants was tough.

But after examining the available records, Dr Henderson suggests that medieval meals were perhaps even better than the much touted "Mediterranean" diet enjoyed by the Romans.

While this would have involved fish, fruit, whole grains and olive oil - as well as red wine - the rich often overindulged, while the poor may not always have been able to obtain them.

The average medieval peasant however would have eaten nearly two loaves of bread each day, and 8oz of meat or fish, the size of an average steak.

MEDIEVAL LIFESTYLE Calories: 3,500 - 4,000 Nearly two loaves of bread Three pints of ale Up to 12 hours labour each day

This would have been accompanied by liberal quantities of vegetables, including beans, turnips and parsnips, and washed down by three pints of ale.

Crucially, there was little refined sugar in their food, while modern eating habits are dominated by biscuits, cake and sweets.

"If you put this together with the incredible work load, medieval man was at much less risk of coronary heart disease and diabetes than we are today," said Dr Henderson.

MODERN LIFESTYLE Calories: 2,700 Fat intake exceeds recommendations Less than 20 minutes exercise each day Greater risk of heart disease and diabetes

However, he did acknowledge that people today did have one advantage over their ancestors when it came to staying alive.

"If you got to 30 in those days you were doing well, past 40 and you were distinctly long in the tooth," he concedes.

Anna Denny of the British Nutrition Foundation said: "This research highlights how much lifestyles have changed over the centuries.

"Today, the majority of adults in the UK are overweight or obese, but energy intakes have actually been decreasing for several decades."