Matt Ridley from the UK: Nobody knows how best to tackle obesity

Even optimists admit that some things are undoubtedly getting worse: things like traffic jams, apostrophe use — and obesity. The fattening of the human race, even in middle-income countries, is undeniable. “Despite sustained efforts to tackle childhood obesity, one in three adolescents is still estimated to be overweight or obese in Europe,” said a report last week to the World Health Organisation. That means more diabetes and possibly a reversal of the recent slow fall in age-adjusted cancer and heart disease death rates.

Perhaps we should remind ourselves first that it is a good problem to have, a symptom of abundance. 

In Britain a century ago and in much of Africa today, the poorest people were or are the thinnest people. For hundreds of thousands of years it was very difficult to get fat, and very easy to starve or be stunted by hunger and malnutrition. Let’s be thankful that, despite quadrupling the global population in less than a century, we now have a problem of obesity, because of a global cornucopia of fine food unimaginable to past generations.

In western countries, obesity is worst among the poor, so it cannot be a matter of affluence alone. Urban areas of England with the highest levels of income deprivation are also the places with the highest obesity rates among young children. By contrast, among the most affluent people, anorexia is a more lethal disorder, and is increasing fast.

At the weekend Tam Fry of the National Obesity Forum claimed implausibly that obesity now costs the state £24 billion a year. The Institute of Economic Affairs puts the cost at less than £2.5 billion, and argues that “while claims of a crippling cost are a good way to get media attention . . . they irresponsibly incite resentment of a vulnerable group”. Also, if you die younger, you cost the state less, so the financial perspective is the wrong way to look at it.

Recognising that something is a problem is not the same as knowing what to do about it. Obesity is one of those cases where “demands for urgent action” go unheeded, not because of the callousness of our leaders but because there’s no agreement on what action to take. The range of suggestions for dealing with obesity — sugar taxes, bans on junk food on public transport, bans on junk food advertising before 9pm, health warnings on fast food, mock-up pictures of what kids will look like as fat adults, gastric balloons — only serves to remind us that nobody knows how best to reverse the obesity trend. Jamie Oliver, the TV chef, argues that the proposed Conservative policy of means-testing free hot school lunches for infants would worsen obesity.

Advising, hectoring and bribing people to eat less and exercise more appears to be ineffective. We have just about tested that idea to destruction. It isn’t working, and it probably will only work if it becomes fully totalitarian, with police raids on home kitchens to seek out and destroy secret stashes of biscuits.

The one thing we do know is that the simple equation so beloved of the medical profession is not the answer. It is not as simple as an in-out calorie balance sheet: eat less than you burn and lose weight. This fails to take into account a thing called appetite, and the way some people lay down fat while eating not very much, while others burn it easily while eating quite a lot.

As Gary Taubes, the heretical science writer who has made a career out of this issue, put it in the British Medical Journal a few years ago, “efforts to cure the problem by inducing under-eating or a negative energy balance, either by counselling patients to eat less or exercise more, are remarkably ineffective”. Even The Handbook of Obesity, the doctors’ textbook, admits that the result of such dietary therapy is “poor and not long-lasting”.

We all know friends who have shed the pounds through superhuman efforts of self-denial, and then gradually put them back on again afterwards. The public health lobby hardly helps by censoriously attacking all “fat and sugar”, or all “processed food”, and often “red meat” too. Which leaves a diet as depressing as it is unrealistic: steamed cod and boiled kale. The public health lobby must make up its mind whether it thinks carbs are bad or fat is bad: attacking both is silly.

Having spent decades urging people to adopt low-fat diets and watched obesity explode, the nannies cannot bring themselves to admit that this was terrible advice which almost certainly made the problem worse. Why? Because fat is satiating in a way that carbohydrates are not, and the body generally synthesises fat from dietary carbs, not from dietary fat. In the Stone Age, eating fat probably signalled a time of plenty, when laying down stores around the midriff was not urgent.

Logically, the heredity of obesity is almost certainly rising. In a world of food shortages, the only way to get fat was to be rich, so obesity was mainly an environmentally determined trait. In a world where so many can afford lots of cheap food, the ones to get fat will often be the ones who inherit some tendency to eat more or lay down more of their food as fat. Given ad-lib food, a greyhound will stay slim while a labrador balloons — it’s in their genes. Not all the variation in obesity between individuals will be explained by genetics but, statistically speaking, there will be greyhound tendencies and labrador tendencies.

Frankly, we just do not know why some people lay down fat more easily than others. Is it because they burn fewer calories even when not exercising? Is their digestion more efficient? Is their appetite greater, so they do eat more? Do they seek out carbs? Is the difference genetic, with some people having variants of genes that encourage fat deposition? Is it because fat people’s gut bacteria are different — a real possibility supported by increasingly persuasive experiments and transplants? All of these theories have something going for them. But not enough to justify the moralising tone and adamantine certainty that so often accompanies medical professionals’ pronouncements on the topic of obesity. We do not know enough.

What should a government do when there’s great uncertainty about both causes and the right course of action? Experiment, of course. Come up with five policies, ask for volunteers in five different parts of the country, and carefully measure the waistlines of people affected.

Matt Ridley, a member of the British House of Lords, is an acclaimed author who blogs at www.rationaloptimist.com.