Our bodies and behaviours are products of our genes and our environment (with a bit of randomness thrown in). Our genes are relatively fixed, but the body they build is not, and nor is the environment. This changing environment can change our bodies (obesity is a good example), and penetrate further, even to change gene expression. This is a life-long process but there is a great interest in how early-life experiences, like stress or exposure to high-energy foods in childhood or even before birth via our mother, can have impacts that last long into adult life. In Nudge-it we will study early-life stress as a potential driver of food choice in adulthood.
Stress is an intrinsic part of life. It can be beneficial of course - it is required for learning and memory, protects against immediate physical dangers and can prepare the body for a future lack of resources. But chronic stress can have a detrimental effect, and from the beginning of our life to its end – birth itself, childhood and adolescence, relationships, education, work, illness – stressors can multiply and press.
Paralleling an increase in stress in developed societies, there is most certainly an increase in obesity. In Europe the prevalence of obesity has increased greatly in the past few decades. Much of the work needed to understand obesity is still ahead of us, but we already know of a large number of inter-related factors that drive eating. These include the impact of stress on eating.
Stress can increase or decrease food intake and, consequently, body weight. But during periods of chronic stress, given a choice between high-sugar, high-fat food or blander food, a substantial percentage of us increase our intake of high-energy food and put on weight. This behaviour is commonly called “comfort eating”, where people who feel chronically anxious or stressed seem to be motivated to consume palatable food. Furthermore, a reciprocal effect is seen where eating palatable foods can suppress the normal physiological stress response. In other words, we may use food to self-medicate against stress.
It can be argued that by adulthood our responsiveness to stress is set, and that if we want to reduce stress in adults we need to intervene in childhood. There is a substantial body of scientific evidence to show that exposure to stress in early-life can program an enhanced response in adulthood. However, the brain mechanisms underlying this enhancement are only beginning to be understood. Furthermore, it is not yet clear whether early programming by stress impacts adult food choice. In Nudge-it a cross-disciplinary group of neurobiologists and economists will investigate this important question.