On Sunday 19 April, the Mayor of London, Sadiq Khan, wrote an article for The Observer highlighting the disproportionate number of black, Asian and minority ethnic (BAME) persons who are critically ill coronavirus patients in our hospitals – around a third of the total.

Although he conceded that a large number of BAME people work in frontline roles, either in the NHS or social care or as bus drivers, he also made the charge that poverty and deprivation were to blame.

“Even though it can be uncomfortable for some to acknowledge,” he wrote, “we cannot ignore the barriers of discrimination and structural racism that exist in our society, which contribute to ethnic minorities being more likely to suffer from poverty, have underlying health conditions and work in insecure, low-paid jobs.” For Khan, “one of the unexpected consequences of this crisis is that the depth of these inequalities is being laid bare in such a stark fashion.” Thus, the crisis is “a wake-up call for our country and a catalyst for far-reaching and fundamental change.”

Taking a different tack in his column for The Times the following day, Trevor Phillips a former chairman of the Equality and Human Rights Commission, suggested the fact that deaths from coronavirus are lower in London boroughs with a high density of Muslims might have something to do with the fact that Muslims wash their hands more frequently for ritual purposes. He also took issue with Khan’s claim that BAME people living in overcrowded accommodation might be the cause, since Tower Hamlets, where a third of the population is Muslim, is a borough with a high level of overcrowded accommodation, and yet it is in the bottom third of London’s infection list.

Yet in all the recent articles about the correlation between deaths from coronavirus and ethnicity, the elephant in the room that no commentator has dared to mention is obesity, even though we had already been told by Public Health England that obese people are more likely to die from the virus.

Nobody wants to be accused of fat-shaming BAME people, thus touching the nerves of two vocal proponents of grievance culture, but it is important that, we should all follow the science, as the oft-repeated credo of these times dictates. And what the science tells us is that the causes of obesity are many and varied.

A July 2019 government study, Overweight adults, found that, “72.8% of Black adults were overweight or obese, the highest percentage out of all ethnic groups,” while the percentage of adults in the Asian ethnic groups who were overweight or obese was “lower than the national average” – partly because their bodies tend to be “Tofi” (thin outside and fat inside).

According to retired GP Dr Christine Dewbury, in a letter to The Times, obesity is “strongly associated” with “insulin resistance and other metabolic changes that harm the cardiovascular system” and this in turn “seems to be associated with the dangerous cytokine storms in Covid-19”.

72.8% of Black adults were overweight or obese, the highest percentage out of all ethnic groups

We knew from early on in the current crisis that type 2 diabetes was a frequent co-morbidity in deaths from coronavirus. And, according to the National Obesity Observatory’s January 2011 study, Obesity and ethnicity, “women of Pakistani ethnicity are over five times more likely, and those of Bangladeshi or Black Caribbean ethnicity over three times more likely, than women in the general population to be diagnosed with diabetes. Bangladeshi men are almost four times more likely, and Pakistani and Indian men almost three times more likely, to have doctor-diagnosed diabetes compared to men in the general population.”

There are also genetic factors to consider. Certain genes have been found to predispose adults of South Asian origin to type 2 diabetes, while nobody can be sure why adults of African descent are more likely to die from strokes but less likely to die from heart disease than other ethnic groups. And there are particular peculiarities that remain unexplained. Why is there a higher level of obesity among Bangladeshi boys, for example?

The moment you drill down into the available data, you discover that the evidence is more complex and less reductive than Sadiq Khan would have us believe. For example, South Asian populations show lower levels of physical activity than the White population, with the Bangladeshi population showing the least physical activity.

These behaviours start in childhood, with Asian girls in particular adopting a more sedentary lifestyle in adolescence than their peers in other ethnic groups. Some Asian parents tell their daughters that sport is incompatible with femininity, while dress codes are another factor. Yes, if you were a burqa you are less likely to engage in exercise. Something as simple as a lack of spaces where an adolescent Asian girl might feel safe to walk – safe from lustful Asian males or racists alike – can make a difference. At the same time, Black Caribbean and Black African adolescents are “the most likely of all groups to skip breakfast and engage in other poor dietary practices”.

Yet another factor is recent migration. Migrants tend to change their dietary habits and some of them will start eating processed foods for the first time. This is likely to lead to an increased prevalence of type 2 diabetes and heart attacks.

Few would argue that poverty and deprivation are not associated with increased obesity, but the effects vary. Contradicting the expectations of racial justice campaigners, London Health Observatory “has found that the increased risk associated with deprivation is greatest for White children, followed by Asian, Other, and Mixed children, whereas it appears to have little effect for Black children.”

The National Obesity Observatory’s Obesity and ethnicity study concluded that it is “unclear how much of the difference in the prevalence of obesity and associated health risks across ethnic groups is caused by biological differences, health behaviours, culture, lifestyle, lower socioeconomic status or differential access to health services”.

If that is the case, and given the strong correlation between obesity and coronavirus deaths, then it follows that the reason for the disproportionate level of coronavirus deaths among the BAME population may be the result of myriad causal factors and not simply a matter of socioeconomic deprivation.