When it comes to our dining habits, there is a giant mismatch between thought and deed; between knowledge and behaviour. ‘Eat food. Not too much. Mostly plants,’ says influential food writer Michael Pollan.15 A wise and simple mantra, much repeated; yet for many it seems anything but simple to follow in daily life. To adhere to it you need to: ‘Like real food. Not enjoy feeling overstuffed. And appreciate vegetables.’ These are skills that many people have not yet acquired, however intelligent or advanced in years they may be. There’s another complication, too. The ‘not too much’ part of Pollan’s dictum needs modifying to take account of those who have learned to eat too little, or at least not enough of the right foods. I am not just talking about the underweight. The term ‘malnutrition’ now covers obesity as well as starvation; there is evidence that obese populations across the world suffer disproportionately from micronutrient deficiencies, notably vitamins A and D, plus zinc and iron.16 Learning how to eat better is not about reducing consumption across the board. While we undoubtedly need to eat less of many foods – sugar springs to mind – we need more of others. Among other lost eating skills – see also not ‘spoiling your appetite’ and not ‘wolfing down your dinner’ – we seem to have lost the old-fashioned concept of ‘nourishing’ ourselves.
A tone of judgemental impatience often creeps into discussions of obesity. ‘It’s not exactly rocket science, is it?’ is a frequent observation on newspaper comment boards, from some of those lucky ones who have never struggled to change their eating, followed by the quip that all that needs to be done to fix the situation is to ‘eat less and move more’. The implication is that those who do not eat less and move more are somehow lacking in moral fibre or brains. But consider this. American firefighters, who are not people notably lacking in courage or quick-wittedness, have higher rates of obesity and overweight – at 70 per cent – than the general population.17 The way we eat is not a question of worthiness but of routine and preference, built over a lifespan. As the philosopher Caspar Hare has said: ‘It is not so easy to acquire or drop preferences, at will.’18
Once we accept that eating is a learned behaviour, we see that the challenge is not to grasp information but to learn new habits. Governments keep trying to fix the obesity crisis with well-intentioned recommendations. But advice alone never taught a child to eat better (‘I strongly advise you to finish that cabbage and follow it with a glass of milk!’), so it’s strange that we think it will work on adults. The way you teach a child to eat well is through example, enthusiasm and patient exposure to good food. And when that fails, you lie. In Hungary, children are taught to enjoy eating carrots by being told that they bestow the ability to whistle. The point is that before you can become a carrot eater, the carrots have to be desirable.
When this book started taking shape in my head, I thought that my subject was childhood food. Bit by bit, I started to see that many of the joys and pitfalls of children’s eating were still there for adults. As grown-ups, we may still reward ourselves with treats, just as our parents did, and continue to ‘clean our plates’, though they are no longer there to watch us. We still avoid what disgusts us, though we probably know better than to throw it under the table when no one is looking. Put a lit-up birthday cake in front of anyone and they are young again.
One of the questions I wanted to explore was the extent to which children are born with hard-wired preferences. As I trawled through endless academic papers in the library, I predicted fierce disagreement among contemporary scientists. On one side, I would find those who argued that food likes and dislikes were innate; and on the other, those who insisted they were acquired: nature versus nurture. To my astonishment, I found that this was not the case. Far from controversy, there was a near-universal consensus – from psychologists, from neuroscientists, from anthropologists and biologists – that our appetite for specific foods is learned.19 Within this broad agreement, there are, as you might expect, still plenty of scholarly disputes, such as the brouhaha over whether our love–hate relationship with bitter vegetables such as Brussels sprouts has a genetic underpinning. There are also competing theories on the extent to which our food learning is mediated by particular genes, hormones and neurotransmitters. But the fundamental insight that human food habits are a learned behaviour is not the subject of scientific debate.
This scientific consensus is remarkable, given that it is the opposite of how we usually discuss eating habits in everyday conversation. There’s a common assumption – shared, curiously enough, by those who are struggling to eat healthily and many of the nutritionists who are trying to get them to eat better – that we are doomed by our biology to be hooked on junk food. The usual story goes something like this: our brains evolved over thousands of years to seek out sweetness, because in the wild we would have needed a way to distinguish wholesome sweet fruits from bad bitter toxins. In today’s world, where sugary food is abundant, or so the thinking goes, our biology makes us powerless to turn down these ‘irresistible’ foods. We know that tasting something sweet activates the pleasure-generating parts of the brain and even acts as an analgesic, comparable to drugs or alcohol. Palaeolithic brain + modern food = disaster.
What’s missing from this account is the fact that, while the taste for sweetness is innate to all human beings and common to all cultures, when it comes to actual sweet foods – and other unhealthy processed foods – we show profoundly varied responses. As one 2012 study of food preferences states, our attitudes to sweetness vary ‘in terms of perception, liking, wanting and intake’.20 Different people enjoy sweetness in very different forms. Sweetness could mean a whole cob of corn at the height of summer; or a plate of milky-fresh mozzarella; or fennel cooked long and slow until it is toffee-brown. Our love of sweetness may be universal but there are vast individual differences in how we learn to ingest it. Put another way: not everyone wants to get their sweet hit in the form of Froot Loops.
Nutritionists use the word ‘palatable’ to describe foods high in sugar, salt and fat, as if it were impossible to prefer a platter of crunchy greens dressed with tahini sauce to a family-sized bar of chocolate. Yet around a third of the population – Palaeolithic brain or not – manage to navigate the modern food world just fine and select a balanced diet for themselves from what’s available.
I’m not saying that to be thin is necessarily healthy. Some of the non-overweight may be anorexic or bulimic. Others avoid food through cigarettes and drugs or burn off a junk-food habit with manic exercise. When we speak of an ‘obesity epidemic’, as well as making those trying to lose weight feel worse than they already do, we miss the fact that the situation is more complex than thin = good and fat = bad. Professor Robert Lustig, a leading specialist on the effects of sugar on the human body, points out that up to 40 per cent of normal-weight people have exactly the same metabolic dysfunctions associated with obesity – ‘diabetes, hypertension, lipid problems, cardiovascular disease … cancer and dementia’ while around 20 per cent of obese people get none of these diseases and have a normal lifespan.21
So we cannot assume that everyone who is ‘normal weight’ has a healthy relationship with food. (Incidentally, given that these people are in a minority, isn’t it time we stopped calling them ‘normal’? How about ‘exceptional’ instead?) The situation is more complicated than the numbers suggest. But I’d still hazard that this exceptional third of the population has something important to tell us. There are hundreds of millions of individuals who somehow swim against the tide of the dysfunctional modern food supply and feed themselves pretty well. There are those who can eat an ice-cream cone on a hot day without needing to punish themselves for being ‘naughty’; who automatically refuse a sandwich because it isn’t lunchtime yet; who usually eat when they are hungry and stop when they are full; who feel that an evening meal without vegetables isn’t really a meal. These individuals have learned the eating skills that can protect them in this environment of plenty.
Viewed through the lens of behavioural psychology, eating is a classic form of learned behaviour. There is a stimulus – an apple tart, let’s say, glazed with apricot jam. And there is a response – your appetite for it. Finally, there is reinforcement – the sensory pleasure and feeling of fullness