Apples or ice cream - who, or what, determines what we eat?

Why, when presented with an apple or an ice cream, do we often go for the unhealthy option when our rational mind is telling us that the apple is the better choice? And how can we overcome the underlying automatic and habitual processes that often undermine healthy behaviours and drive the spread of illnesses such as diabetes and heart disease?

For Professor Paul Fletcher, Bernard Wolfe Professor of Health Neuroscience at the University of Cambridge, the answer lies in understanding that our decision-making processes are not entirely rational, or even conscious, and so approaches that appeal only to logic may well not be successful.

Professor Fletcher will be speaking about the neuroscience of human behaviour as part of this year’s Cambridge Series at the Hay Festival on 31st May. His talk, Apples or ice-cream? Who - or what - determines what we eat?, will discuss the external stimuli - availability and promotion of cheap sweet, salty and fatty food - and internal processes - including stress and anxiety - that act against rational decision-making.

“The idea that the brain is a puppet master is often wrong,” says Fletcher, who is based at the Cambridge University Department of Psychiatry. “We face a lot of other influences, from our bodies, from the environment, many of which are often below the conscious level. Time and again we act in ways that go against our long-term goals, going for more immediate rewards. But most attempts to mitigate this tendency are largely based on education and information which play to the rational mind.”

He says that those environmental stimuli include brands, which often become conflated with rewards. “Brands send out intrinsically powerful stimuli that generate pleasure in themselves,” he says. He mentions experiments in the US on young children which show that the mere presence of a McDonald’s logo on healthier food “seems to shift the value of those foods”, increasing liking for them.

In the past Professor Fletcher’s research has focused on psychosis, but to understand psychosis and psychotic symptoms such as delusions and hallucinations, he says we need to understand the brain basis for how associations are made and how we come to think of particular environmental stimuli as important.

Mitigating health-harming decisions

In his Hay talk he will outline the complexity of the problems faced by those seeking to tackle the problems associated with unhealthy eating. “The challenge is that we are living in a world that is populated by stimuli that can subtly but powerfully shape our behaviours. Given a lot of our drives towards consumption act at a very immediate, unreflective level it is likely that the best approaches to mitigating health-harming decisions and behaviours have to work on that level,” he says.

Some examples are research on plate and glass sizes, moves to replace sweets at checkouts with healthier foods and research on the impact of hormone levels on the brain’s reward system.

Another crucial factor in determining what and how much we eat comes from signals we are receiving from our bodies, says Professor Fletcher. These can be metabolic, hormonal and neural. Exploring how these signals interact with stimuli in the world is going to be an important part of a comprehensive understanding what drives behaviours, he states.

For Professor Fletcher there is no one panacea to tackling the problem of unhealthy eating, but he says it is clear that it cannot be left to individuals or food and drink manufacturers. Moralising and naming and shaming won’t work either and education alone is not enough. He says “strenuous legislation” is likely to be needed which is linked to a long term plan to tackle behaviour-related disease.  

That means developing a deeper understanding of the neurobiological and psychological underpinnings of decision-making and behaviour. Professor Fletcher adds: “A great deal of psychological understanding and skill has gone into encouraging us to consume unhealthy foods. We need to apply the same levels of skill to help people resist these powerful factors.”