The latest edition of medical journal The Lancet features a special series of articles on the problem of obesity. As the front cover declares: 'The conclusions are unambiguous. We need collaborative changes in many aspects of our environment to avoid the morbid consequences of overweight and obesity.'

The figures certainly seem startling. The first special article notes that by 2008, an estimated 1.46 billion adults globally were overweight, of whom 502 million were obese. A further 170 million children under 18 years of age were overweight or obese, too. Yet this problem is not simply associated with wealth. While America has obesity rates among women of well over 30 per cent, Japan and Hong Kong have rates well below 10 per cent. Conversely, some relatively poor countries have seen dramatically expanding waistlines: obesity rates in the Pacific nation of Samoa are over 60 per cent and in neighbouring Tonga, it's 70 per cent - twice the level in the USA.

As the same article notes, the consequences are serious. High body weight is 'an established risk factor for disease such as type-2 diabetes, cardiovascular diseases and many cancers', adding that obesity now accounts for between two and six per cent of healthcare costs in many countries.

Leaving aside questions about whether an association between obesity and disease really means that obesity causes that disease, what is driving this 'pandemic' of obesity? The Lancet concludes that the problem is that governments are not willing to take the necessary action to make us cut down on the amount we eat and increase our physical activity. An editorial declares: 'While business and industry, with their very different aim of making as much money as possible and with an enormous and expensive apparatus of clever advertising, are very effective at nudging people to buy and consume their products, non-regulatory measures to increase consumption of healthy food in isolation are unlikely to be effective.'

In other words, big nasty corporations are seducing us with their products and we are simply too powerless to resist. Instead, government should develop some cojones and start regulating these calorie-pushers immediately.

The trouble is, this is nonsense. It's true that McDonald's and Pizza Hut have big advertising budgets, but it is just advertising. Adverts have nothing like the influential power of the medical profession or even the endless diet of media advice about how and why we should lose weight. While we may like fast food, it is a widely held assumption that it is bad for us. In general, the message that we should eat less - and definitely eat less fatty fast food - while exercising more has been internalised by the whole population. Many women - it is particularly true of women - spend their lives lurching from one diet to another, constantly beating themselves up about every mouthful.

So if we get the message, why don't we act upon it? Maybe because the message is wrong. Forty years of advice to eat less, exercise more and cut out the fat has left Brits and Americans fatter than ever before. Yet the diet experts and our health guardians insist that the problem is that we are either too morally weak to deny ourselves or too mentally weak to resist Ronald McDonald. The result will be ever-greater regulation of what companies can sell and what we can eat.

An interesting riposte to this advice has been provided by the American author Gary Taubes. In two recent books Good Calories, Bad Calories and Why We Get Fat, Taubes argues that it's not how much we eat, but what we eat that makes us - or at least, some of us - pile on the pounds. Instead, the problem is that the obsession with eating a low-fat diet - in the misplaced belief that this will prevent heart disease - has led us to eat more carbohydrates instead. For many people, however, their bodies effectively over-react to carbohydrates, pumping out more and more insulin to deal with the high levels of blood sugar that result from eating carbohydrates, particularly sugar.

What's the effect of insulin? To drive the body to store calories as fat and to keep it locked away when your body is crying out for that energy. The result is that you can eat hearty meals, but those calories get stored. Unable to access that stored energy, your body sends the signal that it needs more food: you get hungry again. It's hunger that drives people who are desperate to lose weight to carry on eating, not clever advertising.

For these people, cutting right down on carbs will prevent that hormonal over-reaction and the process will be reversed, all that stored fat gradually being used up. In other words, the correct health advice is not to eat less but to eat fewer carbs. No need for crash diets or expensive gym membership. I certainly find Taubes's ideas extremely plausible, and I've lost a fair amount of weight in recent months by applying them myself.

At the press conference to launch the special issue of The Lancet on Thursday, there was little indication of self-reflection on the part of the panel of experts calling for greater state intervention to tackle obesity (although one researcher, Dr Kevin Hall, did note there was some evidential backing for low-carb diets). Instead, a major theme was to draw parallels between government responses to 'unhealthy' food and tobacco. As any smoker can confirm, if that route is pursued, the result will be less choice, more nagging, higher taxes and more regulation. Doing for food what has been done to cigarettes is a very unappetising idea.