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,