A message from Boris Johnson drops into my Twitter timeline. “Every weekend at home is making a difference” he says, followed by the usual exhortation: Stay home. Protect the NHS. Save lives.

The easy-on-the-eye, middle-aged, presumably childless, couple in the picture, who look straight out of a brochure for ski holidays in Val d’Isère, are having a whale of a time, sharing a laugh as they look into their laptop screen.

They sit on an aspirational settee, in a classy, loft-like apartment, complete with lush plot plants and tasteful glassed-in book cases painted in the latest shade of Farrow and Ball. Who knew that being stuck in a flat for 15-plus months could be such fun? And so stylish?

For every real human being who conforms to this government image I’ll wager there are thousands for whom the Stay Home ordinance is a living hell, serving up platters on loneliness, anger, mental illness, with a generous side order of cognitive and physical decline.

For them, every locked-down day is more aptly summarised thus: Stay home. Get fat. Get drunk. Get down. Lose fitness. Go nuts.

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As the crocuses push up through the ground and spring trumps winter, the UK and Scottish Governments’ Stay Home guidance is the antithesis of public health.

They should be telling us to get outside and exercise as much as our bones and energy permit, enabling our bodies to make as much vitamin D as possible from any precious sunlight.

Immune system-boosting exercise, particularly in green space, with all its well-proven benefits for mental and physical wellbeing, used to be an actionable prescription for a healthy citizenry.

But if you comply with Stay Home guidance, your ability to exercise is reduced to the bare minimum, and only conditional, a prisoner’s privilege that can be withdrawn at any moment “for the greater good”.

And while government public health gurus miss no opportunity to din Stay Home into our heads, they are mute when it comes to what we can do as individuals to boost our immunity and reduce our vulnerability to this virus. Dr Aseem Malhotra, the campaigning cardiologist and author of The 21-day Immunity Plan, sums up the shift in thinking that’s needed with his alternative mantra: “Eat real food. Protect the NHS. Save lives.” His point is that the virus is opportunistic.

Like other viruses it takes advantage of pre-existing weakness; and in this country we have that in spade loads.

The underlying metabolic health of the UK population is poor, the twin hallmarks of this “metabolic syndrome” being insulin resistance and chronic inflammation.

The conditions that tied up so much NHS resource before covid – heart disease, high blood pressure, Type 2 diabetes, stroke, cancer and dementia – are rooted in metabolic disorder.

More than 60% of us are overweight or obese, a marker for metabolic problems; many thin people are also in less than optimal metabolic shape.

If you’re not convinced of the causal connection between metabolic disease and your level of covid risk, have a look at the latest research to come out of the US, a country where seven out of every eight people suffers from a metabolic issue.

The latest evidence just published in the Journal of the American Heart Association finds that 63% of US hospitalisations for covid may have been prevented if the country had a more metabolically healthy population.

The research found that obesity alone was responsible for 30% of hospital admissions.

The link between bad diet, namely an over-reliance on ultra processed food, and obesity and metabolic ill-health is now supported by six well-conducted longitudinal studies, the latest being a new “cohort” (of exceptional data quality) study from Spain.

It shows that increases in ultra-processed food intake lead to higher belly fat and overall fat accumulation.

Alarmingly, over half the calories we eat in the UK come from that ultra-processed category.

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Good health is predicated on two lifestyle habits: a healthy, nutrient-dense, real food diet, and regular exercise.

But when it comes to covid, government advice ignores the former and restricts the latter. This is the logic that allows NHS vending machines to be stuffed with health-rotting drinks and confectionery.

These advisors are the people who recommend Diet Pepsi and popcorn as “healthy choices”. The adage, “physician, heal thyself”, was never more apt.