The case for action on obesity has “never been stronger”, according to Public Health England , who today publish a review of evidence which shows that being overweight remains one of the biggest risk factors in the battle against Covid-19.

The health agency’s review of evidence relating to weight and the effects of the virus, published on Saturday, found that the risks of hospitalisation, intensive care treatment and death all “seem to increase progressively with increasing BMI (body mass index) above the healthy weight range”.

As other risk factors, such as age, ethnicity and sex cannot be changed, PHE says interventions to help people lose weight or prevent weight gain “may be one of the few modifiable risk factors for Covid-19”.

Coming as Boris Johnson, inspired by his personal coronavirus health scare, prepares to launch his war on obesity, Prof Susan Jebb, professor of diet and population health, University of Oxford, and a peer-reviewer of the PHE report, said it highlighted the need to tackle “the single most important modifiable risk factor” for Covid-19.

“I will be really pleased if we’ll see the prime minister stepping up and acknowledging that obesity is one of the biggest public health problems this country faces, that’s been brought to the fore by Covid,” she said. “Actually, it’s something that we’ve kind of known all along, but it’s just never got to the top of government’s to do list.”

Jebb called for a clampdown on advertising and in-store promotions as well as support for individuals who need it, including referrals to weight loss programmes, warning that “either one of those without the other is going to be inadequate”.

Almost two-thirds (63%) of adults in England are overweight or obese and concerns have been raised that this may have contributed to the high number of coronavirus deaths in the UK.

PHE said the link is “currently unclear” and the data does not suggest that having excess weight increases people’s chances of contracting Covid-19. However, Dr Alison Tedstone, chief nutritionist at PHE, said: “The current evidence is clear that being overweight or obese puts you at greater risk of serious illness or death from Covid-19, as well as from many other life-threatening diseases. The case for action on obesity has never been stronger.”

While there has been much focus on people taking up jogging during lockdown, PHE says evidence indicates that the nation’s exercise levels have not increased overall since before the pandemic. It also highlights a survey which found 42% of people asked in early May about their changes in their eating habits over the previous month said they had snacked more on cakes, biscuits, confectionery and savoury snacks. Sales of snack food and alcohol have also increased from high street shops.

The report does not attempt to quantify the increased risk of severe outcomes from Covid-19 from carrying excess weight but Jebb said the association is “almost linear”. She added: “Every kilo you lose is going to reduce your risk of Covid hospitalisation, and also of diabetes, let’s not forget that.”

The report stresses there is no direct research into the effects of weight loss on Covid-19 risks but PHE says: “It is reasonable to conclude that reducing excess weight could help reduce the risk of severe Covid-19 illness. Moreover, there is good evidence these interventions will bring wider health benefits to individuals and reduce pressures on the NHS due to overweight and obesity”.