Britain was Europe's fattest nation before the coronavirus crisis - does that explain the high death toll?

At 17 and a half stone, with a height of 5 foot nine inches, Boris Johnson was - without doubt -  obese when he was admitted to hospital, suffering from Covid-19.

Since then, the Prime Minister is reported to have lost around a stone, and become convinced that his weight is the reason he ended up in intensive care, fighting for his life.

Mr Johnson has been heard remarking “it’s all right for you thinnies,” when discussing the disease, as well as his renewed vigour to tackle Britains’ war on obesity.

He is not alone. Two thirds of Britons are overweight or obese.

Long before Britain topped European coronavirus death charts, it was already the fat man of the continent, with the highest obesity rates in Western Europe.

Now experts are asking: does one explain the other?

The evidence is mounting. Earlier this month, a study of almost half a million Britons found that being obese doubles the risk of needing hospital treatment for coronavirus. Researchers from Glasgow University found that as body mass index (BMI) increased, so did the risk of having a severe case of the disease.

Now a UK audit of more than 28,000 hospitalised cases shows just how deadly those consequences can be. The latest evidence, released by the Government’s Scientific Advisory Group on Emergencies (Sage), shows that obese patients are 43 per cent more likely to die from the virus.

Meanwhile, research has found that one third of all hospital deaths from coronavirus in England have been among diabetics - the vast majority of cases “type 2” disease, which is fuelled by obesity.

Public Health England has launched a review examining how obesity, along with gender, and ethnicity, can impact on health outcomes. Evidence has consistently shown that men are at far greater risk from Covid-19, with statistics suggesting they are twice as likely to die from it.

In this country, men aged 45 to 64 - Mr Johnson’s age group - are the most likely to be obese, with 36 per cent classed this way, loading the odds against them.

Overall, 29 per cent of adults of all ages are obese, compared with an average of 19.5 in the latest international audit by the Organisation for Economic Co-operation and Development.

Analysis in 2017 revealed the UK as the fattest nation in Western Europe, with obesity rates twice those of countries like Sweden and Norway.

When it comes to Britain’s handling of coronavirus, comparisons are often made with Germany.

Both countries entered lockdown on March 23 - yet Britain’s death toll is now more than 36,000 - more than four times the 8,320 seen in Germany.

Differences between the two countries’ approaches are significant. Germany entered lockdown when just 86 fatalities had been recorded, compared with the 359 seen in the UK. It also embarked on mass testing, carrying out 50,000 tests a day when Britain could not manage this weekly.

But there are also notable differences in the health of the respective populations, with latest records showing obesity rates of less than 24 per cent in Germany, compared with the 29 per cent seen in this country.

And British disclosed this week by SAGE shows just how dramatic an impact obesity has on different age groups. While the mortality risks of Covid-19 rise sharply with age, the impact of obesity actually falls greatest on younger groups, research on those hospitalised shows.

Among under-60s, those who are obese have seen mortality rates of 35.2 per cent, compared to those of 15.9 per cent among those who are slimmer.

Unsurprisingly, the mortality rates among the over-70s the mortality rates are far higher - but the differential on weight grounds is smaller.  Those who are obese have seen mortality rates of 55.7 per cent, while those who are not have seen rates of 52.9 per cent.

The sharpest differences are seen in the younger groups, where total numbers are far lower.

Among those who are hospitalised with coronavirus obese under-40s have seen death rates of 11.7 per cent - more than three times the rates of just 3.2 per cent among those who are slimmer.

It remains unclear why weight carries such a deadly burden, when it comes to Covid-19. One theory is that severe excess weight increases the risk of breathing problems with lack of oxygen one of the main reasons for hospital admission.

Another is that the virus  is linked to increased inflammation, with obese people likely to have a stronger inflammatory response. All of this is complicated by the fact that those with weight problems are far more likely to suffer from a host of other underlying illnesses such as heart and kidney disease, asthma and dementia.

Earlier this week the National Obesity Forum pointed out that around three in four Covid deaths have involved those suffering from such conditions. Obesity is also more likely to lead to complications, such as blood clots.

While scientists attempt to untangle the risk factors, charities suggest desperate - and deeply controversial - measures may be needed to protect those whose waistlines have added to their risks.

This week, charity Diabetes UK said those with the condition may need to be furloughed, if it is not possible for them to work from home, or for workplaces to ensure stringent social distancing rules can be applied, as the lockdown eases.

For years, health officials have warned that Britain’s terrible place in international obesity tables will cut lives short.

Only last year, the head of the NHS warned that obesity had become “the new smoking” and could set back medical advances by decades. Few would have foreseen then that Britain’s obesity crisis could take such a devastating turn.