The coronavirus has shaken the world like nothing else. But beyond the terrible toll of death, economic devastation and fear, the virus is likely to leave another lasting mark.

It is going to make us all fatter.

"I don't know if we are going to come out of this experience stronger, but we will have gotten fatter," warned nutritionist Beatrice de Reynal, who said that was only one thing to do -- eat less.

"It is going to happen to us all, even if we try to exercise," said the similarly fatalistic Julian Mercier, a French sports, health and cooking coach.

With more than a quarter of humanity shut up at home or under lockdown, and with many worried they will get the virus next, the temptation to comfort eat was hard to resist.

"I am the first to turn to chocolate rather than to an apple," Mercier admitted. "And that is what risks being our undoing."

The arithmetic of the situation is hard to argue with. By doing little or none of the physical activity we normally do, an adult is likely to burn off up to 400 fewer calories a day, said dietician Jennifer Aubert.

Which is why we have to reduce our portions and move as much as we can -- as long as it is not to the fridge and back. Other experts point to people who have panic-bought a cupboard full of fresh food, finding themselves duty-bound to eat their way through it.

Slipping into over-eating

Being alone and coping with the stress of the situation, as well as worries about whether they will have a job to go back to, can tip people into over-eating, the British Nutrition Foundation warned. "With concerns about the availability of food, eating well and staying healthy alongside all the other stresses of the coronavirus outbreak is a challenge," it admitted.

"Food can be a comfort and it's easy to overeat when spending so much time at home, especially if you like to cook in order to pass the time."

But it is advising people to embrace the lockdown to learn to "put together healthy meals" which "can be a source of enjoyment and help your well-being". "Canned or frozen ingredients can be just as nutritious as fresh," it added.

Not everyone cooks, however, as Pascale Hebel, of the French CREDOC research institute said, and some may not have the wherewithal to cook. Which can lead to a heavy reliance on fatty and salty ready-meals and tinned food.

Others warned against using food as a way of soothing children forbidden from going outside to play with their friends. "To avoid problems it is easy to make spaghetti bolognese that everyone likes rather than to fight to make them eat spinach," Mercier said. But that would be a mistake.

Experts were unanimous that cooking for yourself and structuring your day with regular meals and physical activity, were vital if we are to come out of this in decent shape.

Stay calm and cook

It can even be possible to lose weight, said Aubert, because "we actually have more time to do sport at home".

And with hashtags like #homemadefood proliferating on social media as users show off dishes and compare recipes, it could also be the chance to teach a whole new generation how to cook.

British celebrity chef Jamie Oliver certainly thinks so and has been doing his bit with a nightly show based on "store cupboard and freezer faves" called "Keep Cooking And Carry On".

It includes dishes fast but healthy dishes such as "Cornershop Curry" and "Quick green pasta"."I understand that it is easy to fall into watching the television, or lying around reading and snacking. I am the first to do it," his French opposite number Cyril Lignac told AFP.

"But this period is a great chance to teach children and teenagers how to cook simple dishes. And when I am at home I tend to cook with less fat and sugar."