Our experience of being human starts with food. It’s central to the journey that our species took to get here. As we evolved, we began to use tools that were associated with food; either the killing of it, or the cutting it up of it in order to eat it. Then we discovered fire, and started cooking on it, beginning a process that saw our brains treble in size. Eating like this also brought us together as a group around a fire, and our lower jaw shrank, as we no longer had to tear through raw cartilage.

To eat cooked food, then, is to be human – it determines who we are. So it’s no wonder that changing what we eat has proved so problematic for public health experts. Altering our relationship with food requires us to re-engineer our most fundamental behaviour patterns. It’s possible, but not easy and it’s why so many New Year’s dietary resolutions are destined to fail by February.

We think we understand eating as a functional process that moves from flavour perception to swallowing, from digestion to nutrition. But it is more than that. Diet influences not only our physical health, but also our mental state, our intelligence, our character and confidence.

We are only beginning to understand this journey. But we do know it starts before birth. A huge amount is learnt in the womb. The flavours of the foods a mother eats, for example, find their way to the unborn child through the amniotic fluid, and after birth those flavours are preferred.

Many experiments have been carried out to assess flavour learning and in one, a set of mothers regularly drank carrot juice when pregnant, while another set drank water. Six months later, all the babies were offered cereal flavoured with carrots, and the children of the carrot-juice-drinking mothers noticeably preferred it. In another version, French babies whose mothers had consumed anis during pregnancy liked the taste immediately after birth, while other babies actively disliked it. Even in the womb, a child is being introduced to the culture and environment into which it will be born.

Similarly, a mother’s poor diet while pregnant can have an effect on the child later in life – but a deleterious one. These children are more likely to become obese, for example. Scientists now believe that the foetus adjusts its metabolism for the world it thinks it will have to face. So if it prepares for a world of scarcity, only to grow up with plenty, then obesity is inevitable.

After birth, the journey continues. Children soon discover that their most effective tool for controlling adults around them is by refusing or accepting different foods. And the food we are exposed to during the first two years of life determines what we want to eat into adulthood. It’s also the case that although it’s vital to serve good food in schools, there simply aren’t enough hours in the school day to counter a regular evening diet of chicken and fries and ketchup.

So what can we do? As parents, both before and after the birth of our children, we can expose them to as many and varied foods as possible. We shouldn’t cut them off from sweet things, but humans were not designed to eat too much sugar. Equally, some fats are fine, as long as they aren’t excessive. Above all, we need protein.

But for those already hard-wired to expect too much sugar or salt, a more intelligent approach is needed to change those habits. There is a role for labelling, but when it comes to food, few of us are truly rational, so giving us perfect information won’t necessarily lead to perfect decisions. There might be a role for taxation, but money has only so much impact in changing our emotional relationship with hot chocolate.

We need to be smarter. We need to fool the brain into thinking it is getting more of a particular taste than it really is. Imagine making a cup of coffee with one coffee bean; it would taste pretty insipid. But consider drinking a cup of hot water and then eating a whole coffee bean; it would have far more impact. You can do the same with food, packaging the release of certain flavours to maximise impact.

There are, in fact, many sensory inputs which affect how we taste something. If you want to accentuate the sweetness of a food item, imagine that you pick up the packet and it’s all soft and smooth, and then there’s a satisfying squidgy noise when you open the lid. It will make a difference.

As strange as it might sound, the whetting of any of our senses can dramatically increase the impact of a small amount of flavour. The weight of the glass you drink something in can change how it tastes, the smell of what you’re eating, the shape of the bowl and feel of the cutlery you use. All of these will have a major impact. Even the language we use has power to alter perception.

So instead of regulating and taxing and dictating, the way to change our eating habits is to fool our brain into thinking it is getting more of what we want than is actually the case.

This isn’t a rational approach, it’s an emotional one, precisely because eating is an instinctive and not a rational activity. Setting aside the rational is a real challenge for policy makers, but if they want us to become less obese as a world, they must realise that laws are often the worst way to change human behaviour.