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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 that eating the tart gives you. This reinforcement encourages you to seek out more apple tarts whenever you have the chance and – depending on just how great you feel after eating them – to choose them over other foods in the future. In lab conditions, rats can be trained to prefer a less sweet diet over a sweeter one when it is packed with more energy and therefore leaves them more satisfied: this is called post-ingestive conditioning.22
We know that a lot of this food-seeking learning is driven by dopamine, a neurotransmitter connected in the brain with motivation.23 This is a hormone that is stimulated in the brain when your body does something rewarding, such as eating, kissing or sipping brandy. Dopamine is one of the chemical signals that passes information between neurons to tell your brain that you are having fun. Dopamine release is one of the mechanisms that ‘stamps in’ our flavour preferences and turns them into habits. Once animals have been trained to love certain foods, the dopamine response can be fired up in the brain just by the sight of them: monkeys have a dopamine response when they see the yellow skin of bananas as they anticipate the reward.24 Anticipating dopamine release is the incentive that makes lab rats work hard for another treat by pressing a lever.
Humans, needless to say, are not lab rats.fn2 In our lives, the stimulus–response behaviour around food is as infinitely complex as the social world in which we learn to eat. It’s been calculated that by the time we reach our eighteenth birthday, we will have had 33,000 learning experiences with food (based on five meals or snacks a day).25 Human behaviour is not just a clear-cut matter of cue and consequence, because human beings are not passive objects, but deeply social beings. Our conditioning is often indirect or vicarious. We do not just learn from the foods we put in our own mouths, but from what we see others eat, whether in our own families, at school or on TV.
As children watch and learn, they pick up many things about food besides how it will taste. A rodent can press a lever to get a sweet reward, but it takes an animal as strange and twisted as a human being to inject such emotions as guilt and shame into the business of eating. Before we take our first bite of a certain food, we may have rehearsed eating it in our minds many times. Our cues about when to eat and what to eat and how much extend beyond such drives as hunger and hormones into the territory of ritual (eggs for breakfast), culture (hotdogs at a baseball match) and religion (turkey at Christmas, lamb at Eid).
It soon became clear to me that I could not get the answers I sought about how we learn to eat without exploring our wider food environment, which is a matter of mealtimes and cuisine, parenting and gender as well as neuroscience.
Our modern food environment is fraught with contradictions. The burden of religious guilt that has been progressively lifted from our private lives has become ever more intense in the realm of eating. Like hypocritical temperance preachers, we demonize many of the things we consume most avidly, leaving us at odds with our own appetites. Numerous foods that were once reserved for celebrations – from meat to sweets – have become everyday commodities, meaning not only that we over-consume them but that they have lost much of their former sense of festal joy.26 The idea that you don’t eat between meals now seems as outdated as thinking you must wear a hat when you step out of the house.
Yet while the nutritional content of our food supply has changed hugely over the past fifty or so years, other aspects of eating have not changed fast enough to keep pace with modern life. Parents are still using a range of traditional feeding methods – such as urging children to finish what’s on their plate – that were devised for a situation where famine was always round the corner. As we’ll see, such feeding techniques are directly contributing to child obesity, in cultures as diverse as China and Kuwait.
The theme I returned to more than any other was families. Most of what we learn about food happens as children, sitting at the kitchen table (if your family is lucky enough to have one), being fed. Every bite is a memory and the most powerful memories are the first ones. At this table, we are given both food and love, and we could be forgiven if, later in life, we have trouble distinguishing the two. It is here that we develop our passions and our disgusts and get a sense of whether it is more of a waste to leave something on the side of the plate or to eat it up when we are not hungry.
Our parents – like governments – hope we will learn about food from the things they tell us, but what we see and taste matters more than what we hear. In many ways, children are powerless at the table. They cannot control what is put in front of them, or where they sit, or whether they are spoken to kindly or harshly as they eat. Their one great power is the ability to reject or accept. One of the biggest things many children learn at that table is that our choice to eat or not eat unleashes deep emotions in the grown-ups close to us. We find that we can please our parents or drive them to rage, just by refusing dessert. And then the adults complain that we are difficult at mealtimes!
After a certain point in our lives, it is us and not our parents spooning food into our mouths. We discover the glorious liberation of being able to choose whatever we want to eat – budget permitting. But our tastes and our food choices are still formed by those early childhood experiences. Rather alarmingly, it seems that our food habits when we were two – whether we played with our food, how picky we were, the amount of fruit we ate – are a pretty accurate gauge of how we will eat when we are twenty.27
The acquisition of eating habits is a far more mysterious skill than other things we learn in childhood, such as tying our shoelaces, counting or riding a bike. We learn how to eat largely without noticing that this is what we are doing. Equally, we don’t always notice when we have learned ways of eating that are dysfunctional, because they become such a familiar part of ourselves. Having particular tastes is one of the ways that we signal to other people that we are unusual and special. We become known as the person in the family who adores munching on bitter lemon rind or the one who eats apples right down to the pips.
You might say that food dislikes do not matter much: each to their own. I won’t give you a hard time for hating the fuzzy skin of peaches if you will excuse my squeamishness about the gooey whites of soft-boiled eggs. The danger is when you grow up disliking entire food groups, leaving you unable to get the nutrition you need from your diet. Doctors working at the front line of child obesity say it has become common in the past couple of decades for many toddlers to eat no fruit and vegetables at all. This is one of the reasons constipation is now such a huge – though little mentioned – problem in Western countries, giving rise to 2.5 million doctor visits a year in the US.28
Some hold the view that it doesn’t really matter if children have unhealthy tastes, because once they grow up they will effortlessly acquire a penchant for salad, along with a deeper voice and mature political opinions. Sometimes it does work out this way. Love and travel are both powerful spurs to change. In the 1970s it was a common rite of passage to reject the conventional bland watery foods of a 1950s childhood and embrace mung beans and spice. Many tastes – for green tea, say, or vodka – are acquired, if at all, in adulthood. When we learn to love these bitter but lovely substances, we undergo what psychologists call a ‘hedonic shift’ from pain to pleasure.29 You may overcome your childish revulsion at the bitterness of espresso when you discover the wonderful after-effects, how it wakes up your whole body and infuses you with a desire for work. The great question is what it takes for us to undergo a similar ‘hedonic shift’ to enjoying a moderate diet of healthy food.
The process will be different for each of us, because all of us have learned our own particular way of eating. But wherever you start, the first step to eating better is to recognize that our tastes and habits are not fixed but changeable.
There’s a danger here that I’m making the process of changing how you eat for the better sound easy. It isn’t. In particular, it isn’t easy for those who feed themselves on a tight budget. Many have observed that – in developed countries – obesity disproportionately affects those on low incomes. Poverty makes eating a healthy diet harder in numerous ways. It’s not just because it is far more expensive, gram for gram, to buy fresh vegetables than it is to buy heavily processed carbohydrates. Maybe you live in a ‘food desert’ where nutritious ingredients are hard to come by; or in housing without an adequate kitchen. Growing up poor can engender a lifetime of unhealthy food habits, because a narrow diet in childhood is likely to narrow your food choices as an adult, even if your income later rises. When the flavour of white bread and processed meat are linked in your memory with the warmth and authority of a parent and the camaraderie of siblings, it can feel like a betrayal to stop eating them.
Yet it’s striking that some children from low-income households eat much better than others, and sometimes better than children from more affluent families. The problems with how we eat now cut across boundaries of class and income. It is feasible to create decent, wholesome meals – bean goulash, spaghetti puttanesca – on a shoestring budget. Equally, one can have the funds to buy chanterelle mushrooms and turbot but no inclination to do so. According to feeding therapists with whom I have spoken, there are successful business people who will – literally – pass out from hunger at their desks rather than allow an unfamiliar meal to pass their lips when their preferred junk food is not available. Assuming you are not living in a state of famine, the greatest determinant of how well you eat is the way you have learned to behave around food.
This behaviour is often immensely complex. As we grow up, we become capable of second order preferences as well as first order preferences. A first order preference is basic: you love crispy roast potatoes, smothered in butter and salt. A second order preference is more convoluted: you want to like eating carrots instead of the potatoes because you think they would be less fattening and healthier. Indeed, you probably can, at least sometimes, limit yourself to eating raw vegetables instead of the carb-laden potatoes. But the real question is what happens next. In 1998 the social psychologist Roy Baumeister did a famous experiment. Baumeister, who is known for his work on self-defeating behaviours, found that the struggle of will required when a group of people were asked to eat ‘virtuous’ foods such as radishes instead of the foods that they really wanted, such as chocolate and cookies, led to diminishing returns.30 They were so depleted by the effort of the task that when faced with another difficult task – solving a tricky puzzle – they would give up more quickly. The emotional effort of not eating the cookies had a ‘psychic cost’.
Changing our food habits is one of the hardest things anyone can do, because the impulses governing our preferences are often hidden, even from ourselves. And yet adjusting what you eat is entirely possible. We do it all the time. Were this not the case, the food companies who launch new products each year would be wasting their money. After the fall of the Berlin Wall, housewives from East and West Germany tried each other’s food products for the first time in decades. It didn’t take long for those from the East to realize that they preferred Western yoghurt to their own.31 Equally, those from the West discovered a liking for the honey and vanilla wafer biscuits of the East. From both sides of the wall, these German housewives showed a remarkable flexibility in their food preferences.
There is hope as well as concern in the fact that we remain like children in our eating patterns. We are like children in our fussiness and love of junk. But we also remain like children in that we have a capacity to learn new tricks, one that we seldom credit ourselves with. Even though most of us have tastes acquired very young, we can still change.
When I was a teenager I could eat whole pint-sized tubs of ice cream, and second and third helpings of everything. Everywhere I went, food screamed at me. Maybe it was a response to living with my older sister, who was anorexic, though this was never mentioned, because in our family we did not speak of such things. Or it could have been a consequence of growing up in a house where emotional talk was taboo. It definitely got worse when I was fourteen and my parents separated. Overeaters often say they are swallowing their feelings.
Around the age of twenty, something changed. I fell in love, got happier and my meals became more structured. I shrank from large to medium, without ever particularly dieting. I ate lots of vegetables, not because I had to, but because they were delicious, and they made me feel good. Then I had children. I could now bake a whole chocolate cake, eat a small slice and leave the rest. Recently I discovered yoga. My teenage self would have found my current self intensely annoying.
The strange thing, however, is that my behaviour changed without me ever particularly noticing that this was what was happening. Unlike the adolescent diets that I imposed on myself in a conscious, self-correcting way, this new healthier life crept up on me unawares. It’s not that I never carry on eating crisps long after I am full, especially when there’s a glass of wine in my hand. I may be safe around chocolate cake, but I wouldn’t fancy my chances with a Vacherin Mont d’Or cheese in the kitchen. But I have definitely reached the point where my second order food preferences – I want to like greens – and my first order food preferences – I do like greens – are fairly in sync. Food no longer screams but speaks to me. It helps that our concept of healthy eating has enlarged in recent years to take in satisfying meals such as chicken and chickpea soup, buckwheat pancakes, avocado toast or buttery scrambled eggs with herbs. I’m in the groove now of eating smaller lunches and larger dinners, but small or large, meals are occasions for pleasure, not angst. This feels good. I must have relearned how to feed myself somewhere along the way, treating myself with some of the solicitude I bestow on my children.
E.P. Köster, a behavioural psychologist who has spent decades studying why we make the food choices we do, says that food habits ‘can almost exclusively be changed by relearning through experience’.32 That is, if we want to relearn how to eat, we need to become like children again. Bad food habits can only change by making ‘healthy food’ something pleasure-giving. If we experience healthy food as a coercion – as something requiring willpower – it can never taste delicious.
It’s seldom easy to change habits, particularly those so bound up with memories of family and childhood, but, whatever our age, it looks as if eating well is a surprisingly teachable skill. This is not to say that everyone should end up with the same tastes. Life would be dull if everyone preferred satsumas to clementines. But there are certain broad aspects of eating that can be learned and then tailored to your own specific passions and needs. There are three big things we would all benefit from learning to do: to follow structured mealtimes; to respond to our own internal cues for hunger and fullness rather than relying on external cues such as portion size; and to make ourselves open to trying a variety of foods. All these three can be taught to children, which suggests that adults could learn them too.
For our diets to change, as well as educating ourselves about nutrition – and yes, teaching ourselves to cook – we need to relearn the food experiences that first shaped us. The change doesn’t happen through rational argument. It is a form of reconditioning, meal by meal. You get to the point where not eating when you are not hungry – most of the time – is so instinctive and habitual it would feel odd to behave differently. Governments could do a great deal more to help us modify our eating habits. In place of all that advice, they could reshape the food environment in ways that would help us to learn better habits of our own accord. A few decades from now, the current laissez-faire attitudes to sugar – now present in 80 per cent of supermarket foods – may seem as reckless and strange as permitting cars without seatbelts or smoking on aeroplanes.33 Given that our food choices are strongly determined by what’s readily available, regulating the sale of unhealthy food would automatically make many people eat differently. Banishing fast-food outlets from hospitals and the streets surrounding schools would be a start. One study shows that you can reduce chocolate consumption almost to zero in a student cafeteria by requiring people to line up for it separately from their main course.34
