Fat is a public issue - and a private grief when I am looking in the mirror

The other night I dreamt I had a six-pack again. I looked down, and there were these washboard abdominals, as hard and as exaggerated as if they had belonged to an action-man doll. In the dream they were my reward for months of exercise and mild restraint, which I have actually been enduring in the real world.

The other night I dreamt I had a six-pack again. I looked down, and there were these washboard abdominals, as hard and as exaggerated as if they had belonged to an action-man doll. In the dream they were my reward for months of exercise and mild restraint, which I have actually been enduring in the real world.

The origin of the dream is not hard to work out. This September seems, among other things, to be Smash Obesity Month (if such a gelatinous quality as obesity can be smashed). Last week we had scientific audiences in Leicester being told that increased human body weight and mass represents a major evolutionary change, wrought in just a few short years. Over a century or so the agricultural revolution added inches to the heights of Europeans, but in the short 20 years since 1980, a Professor Andrew Prentice revealed, the average man has gone from weighing 74 kilos to 82, and a woman from 62 to 69. In England (as opposed to the UK) the percentage of men aged 16-64 who are obese has risen from 6 per cent to 15 per cent, and women from 8 per cent to 16.5 per cent.

My own personal evolution (horribly visible in a recent programme on University Challenge, showing the author as a young gazelle back in 1975) has been pretty stunning. As of last June I had registered a 40 per cent increase in body weight from early adulthood – 40 bloody per cent! A skinny adolescent, with embarrassing sticky out ribs had, bit by bit, metamorphosed into a walrus with thin legs.

Yesterday yet another obesity expert, Professor Philip James, chairman of the International Obesity Task Force, reminded us of the problems caused by my type of progression. They are listed on his organisation's website: respiratory difficulties (not yet), musculo-skeletal problems (dodgy knees), skin problems (nope), infertility (too late to matter), non-insulin dependant diabetes (no), gallbladder disease (not so far), cardiovascular problems such as hypertension (yes, got that, taking the pills, don't like it), stroke and coronary heart disease, cancers associated with the large bowel (colon polyp discovered last week, prognosis good) and premature death (I just want to say, aaagggghh...).

The knowledge of these dangers has now got me swimming walking and yoga-ing up to six times a week, an inconvenient amount of time to spend pampering myself when life is so busy. And I have sworn off certain favourite but fatal foods yet again. It is the biggest battle I have fought since giving up smoking 10 years ago.

If it's hard for me, how much more difficult must it be for those with less money and less time? Yet the trend line is pretty clear. For all the talk of genetic predisposition limiting the problem, it is quite possible that 75 per cent of Britons could be overweight by 2017, and that half of those will be properly obese. Obesity, and not smoking, will be the nation's top preventable killer. Worse (and here the campaigners aim right for our most vulnerable spot), it is among our children that the obesity epidemic will be most felt. Professor James foresees overflowing junior diabetes wards, thousands of 30-year-olds with diabetes-related blindness, a chronic shortage of dialysis and a country of people waiting – mostly in vain – for kidney donors.

Yesterday a strident Prof confided to a radio interlocutor that he thought that governments in general (and ours specifically) had done far too little to contain the epidemic. This accusation was then raised – with statutory belligerence – with a government medic. What had the Government done to make children thinner? Tell me! I hardly need to add that, had the medic come on to the programme to outline government plans to take action on obesity, the words "nanny state" would have been chucked at him with equal ferocity.

We'll return to who should do what to whom after a little canter through the causes of obesity, which are, of course, all related to a gross excess of physical energy consumption over energy use. Professor Prentice believes that obesity is a fairly natural (if undesirable) consequence of our new circumstances. He calls it a "normal biological response". If frogs were to find that their food piled up on lily-pads without having to be caught, they'd get fat too.

Our lives are far less full of physical effort than once they were, and high-octane (and, to us, delicious) food is far more easily available. Life provides many more sedentary diversions than 40 years ago (when I was a kid there was almost no telly during the day, and we had to go outside for entertainment). And clever old capitalism not only excels at selling me products that I know I want, but is also brilliant at persuading me to buy things that I had no idea I desired until I saw them on the shelves. I never asked for 400g tubs of Haagen-Daz's banoffee ice cream.

None of these things are, in themselves, bad. Who wants to go back to the days when shopping took most of the morning of every weekday, and had to be toted back on the bus, alongside the toddler, the push-chair and a double hernia?

One response to this is to be disgusted with what a dreadful, gluttonous, moronic bunch we all are, and what a bad society we live in. So, a media medic, writing in a weekly periodical this week, remarks that "Inactivity and gross overeating are not just possible for the young, but are unopposed by countervailing cultural pressures".

If only that were true. There would be no weight-watchers. Instead, meetings of Skinnies Anonymous would feature rooms full of aerobic instructors and supermodels discussing how to put on weight. "And Tara," the group leader would say, "is that the first hint of cellulite I see appearing on your bum cheeks! Applause for Tara, everyone!" The extraordinary conundrum is that we simultaneously loathe fat and are getting fatter – as though we were somehow out of control. I can think of no other example of how millions of people – as a consequence of their own actions – become the thing that they least want to be.

So now we return to the question of what, if anything, we should do about it. And recognise that we are talking here about billions of bits of individual behaviours, and not just about nasty food companies and their cunning plans to sell us salty, sweet, deathly titbits.

The obvious proposition is that we need to mount a co-ordinated campaign and do for killer flab what we have already done for fags (but not booze). Except this campaign would be far more problematic, since it would entail doing something (ie exercise) and not just not doing something.

This is about more than schools banning fizzy drinks and crisps, and encouraging fruit-eating. It involves radical changes to the way we look at exercise. We must devise regimes that kids like (and not keep moaning on about competitive sports, which many of them don't). We have to get more people walking and cycling to work, which means paying for them to travel on un-carred routes. How about tax breaks for gym use?

Or, instead, we could die – it's our choice, really.

David.Aaronovitch@btinternet.com