Tom Sutcliffe: Consumer choice is what's making kids fat

Social Studies: The PR company promoting Change4Life also has Kentucky Fried Chicken, PepsiCo, Mars and Pizza Hut on its client list

The Government wants under-fives to "huff and puff" for at least three hours a day, according to new guidelines on exercise for children. In my own experience, advice on getting children under five to sit still for more than five minutes would have been more useful – but there's no mystery as to why this faintly ludicrous directive has been issued. NHS figures show that nearly a quarter of four and five year olds are now overweight or obese and the graph is pointing ominously upwards.

Even allowing for a certain bureaucratic neurosis, there's a serious public health problem here – and a recent report on obesity in America offers a clue as to why neurosis might count as a rational response. F as in Fat: How Obesity Threatens America's Future 2011 records the astonishing speed at which America continues to bulk up. Twenty years ago no state had an obesity rate above 15 per cent. Today two out of three states have obesity rates over 25 per cent. With an adult obesity rate of 19.8 per cent, Colorado can now proudly claim to be the trimmest in the Union; a mere 15 years ago the same figure would have made it the fattest.

No great mystery, either, as to the source of this epidemic bloat. It's consumer choice, the sacred principle hymned by industrial food producers in their attempts to resist government regulation and then exploited – through the application of food technology to innate human craving – to make cheap food irresistibly palatable. And yes – consumers do have a choice as to whether they stuff themselves with corn syrup and hydrogenated fats – but that choice is constrained by availability and information, and bent further out of truth by the billions spent on advertising junk-food.

Any attempt to regulate or constrain these blandishments tends to provoke a positively aerobic level of indignation from those whose profits depend on them. The Federal Trade Commission has just tried to introduce voluntary guidelines on advertising unhealthy food to children in the United States – voluntary, I repeat – a move immediately rejected as "reckless" in the light of current economic difficulties. Far more sensible, of course, to encourage the country to eat itself towards cardiac arrest.

Things aren't much better here. One of the Coalition's early moves in government was to side with manufacturers in opposing Traffic Light nutrition labels (despite the fact that consumers find them more useful than Guideline Daily Allowances). They also agreed that, in return for their adoption of a non-regulatory approach, the food industry would fund and develop the Change4Life campaign introduced by the Labour government.

It's perhaps a little early to say how effective this will be in the long run – but there are surely grounds for scepticism. The PR company paid to promote Change4Life, Freud Communications (run by Matthew Freud, Rupert Murdoch's son-in-law), also has Kentucky Fried Chicken, PepsiCo, Mars and Pizza Hut on its current client list. Exactly how eager is PepsiCo going to be to promote tap water or Mars to suggest that you replace a chocolate bar with an apple? The truth is that if the government really wants to prevent this country going the way America already has, it's really not five-year-olds that it needs to make huff and puff a bit more. It's food industry lobbyists and the companies who pay them.

The unisex cloak of invisibility

I read over the weekend of the plight of women of a certain age – "I am", writes a protesting female blogger, "plankton on the food chain of sexuality". I'm not sure her metaphor entirely works (doesn't plankton get snapped up indiscriminately, rather than ignored?) but her sense of social exclusion is confirmed by a recent survey which found that eight out of ten women over 50 think they have become invisible to men.

It's even echoed in my own house: "Thinking of organising a pride parade for all of us 45-plus women to flaunt our Spanx, reading glasses and Fit Flops and be loud and proud", my wife tweeted the other day, after finding herself in central London on Gay Pride day. I am, of course, deeply sympathetic, but I can't help wondering at the suggestion that it's any different for men. I haven't noticed that my own badges of maturity draw interested glances from women in the street. In fact I've got inured to precisely the same experience of ghostly transparency that women complain of. Above a certain age you're about as visible to the young as a bollard or a bus stop; that is, you're there in the peripheral vision because no one actually wants to bump into you, but if you expect a gaze to linger, you're a fool. It's no consolation, I guess, but in this, ladies, you really aren't alone.

No fairytale ending to the Murdoch saga

The gratified tone of some liberal commentators over the weekend – announcing that Mr Murdoch's sinister power had finally been broken – was understandable, but still a little worrying. Have none of them ever seen a Hollywood thriller, in which the panting relief of a victim is the invariable prelude to a renewed assault?

And have they never played a video game – in which climactic Boss Battles play out as alternating bouts of vulnerability and renewed aggression? I guess the answer to that last question is no – but I'm willing to bet that the current narrative will fit modern models a lot more closely than the tale of magically broken enchantment that some pundits have already started writing.

t.sutcliffe@independent.co.uk