A fat lot of notice we British take of the food experts, says Rose Prince, and, when times are tough, there's less point than ever in telling us to cut out treats

Tell the credit-crunched to watch their diet? It's a waste of time. The board of nutrition experts who this week begged celebrity chefs to leave the cream and butter out of their recipes picked a bad moment. There is evidence that we are changing our habits – cooking more rather than eating convenience food – but we will not necessarily do it in a way that is healthier. Time and again self-styled health experts, such as this Fat Panel, show their ignorance of the way people really eat.

As D J Taylor observes, in The Road to Wigan Pier, George Orwell's survey of 1930s working-class life in Britain, there is a revealing piece lamenting the eating habits of the unemployed. He says the weekly family spend of a jobless miner set aside nothing for fruit and less than 0.3 per cent for green vegetables. "The basis of their diet ... is white bread and margarine, corned beef, sugared tea and potatoes – an appalling diet," Orwell complains, adding that it would be better to spend more on "wholesome things" like oranges and wholemeal bread.

But human nature doesn't work like that. Orwell knew then what the Fat Panel still will not admit: such advice is pointless: "The ordinary human being would rather starve than live on brown bread and raw carrots. And the peculiar evil is this, that the less money you have, the less inclined you feel to spend it on wholesome food."

The richer we are, however, the more minimal our diets. You could define the past decade by the shrinking of portion sizes and the pursuit of thinness by the upwardly mobile and financially successful. Gossip magazines and the women's pages of the Daily Mail have kept a constant eye on the contours of Victoria Beckham and Keira Knightley, making regular checks on protruding hip, collar and cheek bones.

Even curve icon Kate Winslet has finally been brought into line and lost every ounce of her celebrated (though still relatively small amounts) of fat. Holiday times are a study of wealthy bodies on the beaches of luxury hotels. The paparazzi lenses were not invited, but every girl on her way to stardom now knows she could not do it without a low calorie score.

Celebrity restaurants are there to help. You could wolf the entire menu at Nobu and still only consume a few hundred calories. Other popular hang-outs deal with temptation by serving tiny helpings. At Gordon Ramsay's Maze there are approximately three mouthfuls per dish. You can order several and share, but this style of dishing-up is perfect for discreet dieting in chic surroundings. This is what you hear in Maze: "You must have the last one – please." "Oh no, really, you must have it. I am so full, I can hardly move." Weakened by starvation, more like.

The other side of the coin is now the obesity epidemic. The rich-poor divide is also the thin-fat divide. Obesity is a disease of adults and their children in lower-income groups, few of whom buy cookery books, for heaven's sake. They do watch an awful lot of television, however. It's the time-filler – the sugary tea of life – especially for those without jobs. And if you watch a lot of TV, you do not have to buy cookery books with all their inherent naughty ingredients, because the schedules are full of cookery programmes.

So that should solve the problem, no? No. Celebrity chef programmes should be the healthy counterculture, contradicting everything that I have said so far. But food TV does not change the dietary habits of those who really need to change. Obesity is still on the increase. The latest statistics from the NHS, published on 25 February, show a 30 per cent increase in diagnosis of obesity in adults and children between 2007 and 2008, a 16 per cent increase in prescriptions issued in the same period and a 40 per cent increase in surgery to treat obesity-related illness. Between one-fifth and one-quarter of children and adults consume five portions of fruit and vegetables a day, meaning at least three-quarters of the nation are still eating the diet Orwell called "appalling" over 70 years ago.

It seems that the beneficial influence of TV cookery is an illusion. Generally viewers watch others cook so they do not have to do it, proof that the British have the most dysfunctional eating customs in the West.

Jamie Oliver, praised by the Fat Panel for the way in which he uses olive oil in place of butter, has campaigned for better eating habits, but it seems to have had little impact on low-income groups. Yet he has real God-like status, appearing on chat shows, giving evidence to parliamentary committees, receiving awards; he is even married to a very slim, former model.

Audiences watch Nigella Lawson because she behaves rather disgustingly around food, raiding the fridge after a party for leftovers, running a finger around a bowl of chocolaty mixture and putting lots of cream into everything. It is pure entertainment. None of it is meant to be taken seriously. She sells a lot of books on the back of the programmes, but do people change their eating habits because of it? Not really, at least not until now.

For there finally does appear to be a real change towards more home cooking. Gill Holcombe, a housewife who wrote an impassioned book about feeding a family on very little money and no proper equipment, has sold 30,000 copies in paperback. Supermarkets report that sales of ready-made cottage pie are down while potatoes, onions and beef are up. Marks & Spencer launched an "ingredients" range to complement the ready-made foods that have been their trademark, and have seen extraordinary sales figures for items like plain flour, yeast, chicken stock, pulses (beans, grains etc.)

A return to cooking means at least something is good about the recession. But then the self-styled health experts blunder in with advice, deterring new cooks from using the recipes of their favourite celebrity chefs. The Fat Panel suggests that cooks substitute margarine or spreads for the butter in celebrity recipes to reduce the content of saturated fat. Margarine and spreads are less nutritious or wholesome than butter, containing various degrees of unhealthy transfats.

But then the Fat Panel receives grants from the Margarine and Spreads Association. Instead of targeting the fledgling cooks or the books from which they are tentatively cooking, the panel would be better employed attacking the food industry that makes the processed junk that is also a cause of obesity – junk like margarine, which is added to a lot of other processed snack foods.

If at last there is a trend towards buying more ingredients and cooking them at home, and a move against takeaway or convenience food, self-styled advisers like the Fat Panel should not confuse the issue, opportunistically pleasing those that fund them – but just let everyone get on with it.

We are going to be poorer over the next few years, so we are going to cheer ourselves up with buttery food and get a little fatter. With cookery books on the kitchen counter, there is a chance to balance the butter intake with plenty of green vegetables and other wholesome ingredients.

If cookery is back because consumers of every income group are finding it a cheaper way to eat, and if the TV chefs can be useful and not just there for our entertainment, leave them to it. And keep the butter in. Our food culture should be sublime, not ridiculous.