It is only natural on these cold, dark winter nights to eschew salad in favour of comfort food and curl up on the sofa in front of the television rather than head for the gym.

Imagine, then, how indignant you would feel if Gordon Brown decided to slap a heavy tax on potato chips or chocolate bars and offered cash incentives only to those willing to weigh in with a healthy body mass index or check into a gym several times a week. You can hear the cries now: Gordon's nanny state!

However, Peter Ubel, believes that government intervention may be the only way to combat a variety of society's ills, including obesity. The American physician is causing quite a stir across the Atlantic with his book Free Market Madness, which will be published in the UK next week. In the book — subtitled Why human nature is at odds with economics and why it matters — he argues that we are irrational beings who need saving from ourselves.

Dr Ubel says that governments must intervene because we do not tend to make rational choices, we don't generally assess risk accurately (we “feel” rather than calculate risk), few of us have learnt self-control and most of us are hopelessly optimistic. He is particularly angered by those who argue that obese people, drug abusers, alcoholics or even those who are in dire debt have simply made some poor life choices that they can easily reverse with a little willpower.

“Using heroin is not simply a [rational] choice someone made, by weighing up the costs and benefits of life with heroin versus life without heroin; it is a physiological addiction that gets woven into the social fabric of their lives and it is really hard for them to quit.”

Although Dr Ubel believes that government intervention should always be considered, he is not an advocate of it in every case. He told The Times: “When a problem is going to occur in a free market, then you have to say: ‘Is this problem big enough that the Government should step in and do something about it?'. The answer is going to depend on what the Government has to do and how onerous it is. There is no simple answer and regulation is not always the answer.” Too much regulation, for instance, “would stop us growing up and thinking for ourselves”. He says: “It is about achieving a fine balance between regulation and self-governance.”

However, Dr Ubel is quite definite that when it comes to our eating habits, governments need to act fast. He says: “The question isn't whether the Government should fix the [obesity] problem but how it should fix the problem. If we want to combat obesity, we will ultimately be forced to make some difficult decisions about whether to restrict some valuable liberties to achieve important goals.”

Ways in which he suggests governments might intervene include tax rebates for people with appropriate body weight, subsidies for healthy food and taxes on unhealthy food, subsidies for membership and travel to gyms, regulation of restaurants and restrictions on advertisements for unhealthy food. All of this could be combined with school programmes to promote healthy eating and exercise.

And in case you believe that those multicoloured symbols and calorie counts on food packets are enough, Dr Ubel is adamant that information alone rarely has an impact on our behaviour. He says: “Freedom is a wonderful thing, but not so wonderful that it should exist, unrestrained, at the expense of people's wellbeing.”

There are flaws in his argument. Aside from the inability to measure outcomes, there is our innate resistance to being controlled, the difficulties of changing cultures and the simple fact that we might actually be happy with our unhealthy choices.

And if taxpayers are going to foot the bill for subsidies and interventions, we will want solid proof that they work. However, as Dr Ubel says: “You cannot measure the ultimate outcome, which is happier, healthier, more productive adults.”

Despite all this, he says: “I am deeply disturbed that political debates about the issues I discuss are too often hijacked by free-market extremists who squeal 'nanny state' whenever we propose setting limits on people's freedom. But when freedom and wellbeing collide, we should be open-minded enough to recognise that carefully planned, calibrated restrictions on our freedom are a small price to pay for a healthier, happier populace.”

Rational though his arguments may sound, his ideas are unlikely to be vote-winners for Mr Brown or David Cameron. So for that reason alone, those of us who remain irrational — and proud of it — are safe to curl up on the sofa with a large box of chocolates.

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