How do we choose what, when and how much to eat? It’s a simple question but a complete answer is currently impossible to give. Of course, we need the energy and nutrients present in food to allow us to live, and this idea of energy balance is familiar - we use a varying number of calories each day and need to replace them. But it is certain that we don’t eat only because we’re hungry. Imagine that eating was driven only by energy balance (homeostatic) mechanisms; that we only ate the calories and nutrients that we needed. If that were the case then neither obesity nor conditions featuring low body weight would exist. If we ate a little too much one day, we would eat less the next and our body weight would remain stable. This does not happen.

We know that it is unhealthy to be over- or underweight, and many of us will have tried to lose weight or tried to avoid putting it on in the first place. But preventing or reversing weight gain is hard. Diets and exercise, alone or together, can work reasonably well in the short-term, but any weight loss is usually regained, with a little extra on top. Medicines to reverse obesity have a very poor history, many have been withdrawn due to side-effects. Currently the only successful treatment for obesity is bariatric surgery but this is expensive, irreversible and its long-term effects are not yet known.

Keeping a healthy body weight is exceptionally hard. It can feel that many influences drive us towards eating. We need to think about how obesity can be avoided, about how we can make better decisions when choosing foods. In Nudge-it we aim to better understand how we make decisions about what to eat. The project takes a multi-disciplinary approach to examine the importance of four influences on food choice: early-life experience, the environment, habit and impulsivity, and emotion.

There is a large amount of experimental evidence suggesting that experiences during early life can “program” behaviour as adults. These early-life experiences do not just encompass those in young childhood, but earlier yet - prior to birth. It’s clear, therefore, that we need to be able to understand and give advice on how pregnant mothers can do their best for their children. In Nudge-it we will look at the effects of early-life exposure to stress or high-energy foods on behaviour in adulthood.

The food environment has a huge influence on food choice. Choices can only be made where they exist, and in the developed world at least, we are lucky to live in a food environment where calories and nutrients are abundant, safe to eat and inexpensive. But how does this abundance affect choice? Is a calorie a calorie independently of its source, or do different foods affect our body weight differently? In Nudge-it we examine these questions to better understand choices around how and when we eat.

Much of our daily behaviour is habitual - it’s fixed, repetitive, and with little thought for its consequences. Eating behaviour is often habitual too, we eat the same things at the same time of day. But how are habits formed? Eating can also be impulsive; some foods seem to attract our attention irresistibly. What drives the momentary choices we make to eat high- or low-energy foods? What underlies this impulsive behaviour? In Nudge-it we will study the influence of metabolism and homeostatic control on habitual eating and impulsivity.

Mood and emotion are very influential in behaviour. Negative mood (sadness, anger, guilt) is known to affect eating behaviour, but little is known about positive effects (happiness, self-confidence and cheerfulness). This is a major omission in our understanding of food choice, with potentially important implications not just on helping us control body weight but on mental well-being in general.