The one thing that can undermine your best intentions

We all know the importance of making healthy food choices, especially at this stage of our lives. But even those who set out at the beginning of the day with the best of intentions can find themselves reaching for junk food by lunchtime – and scientists think they now know why.

In a study appearing in Neuron, researchers used human volunteers to explore how stress changes the brain, impairing our self-control when confronted with a choice.

They selected two groups of people who made a conscious effort to maintain a healthy lifestyle and presented them with the option of eating a very tasty but unhealthy item or one that was healthy but less tasty.

Prior to being offered the food, one group was subjected to a test known to induce stress – immersing a hand in an ice water bath for three minutes.

When it came time to choose their snack, the group who had received the ice-bath test were more likely to choose the unhealthy food than those who weren’t stressed.

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“Our findings provide an important step towards understanding the interactions between stress and self-control in the human brain, with the effects of stress operating through multiple neural pathways,” says lead author Silvia Maier, of the University of Zurich’s Laboratory for Social and Neural Systems Research. “Self-control abilities are sensitive to perturbations at several points within this network, and optimal self-control requires a precise balance of input from multiple brain regions rather than a simple on/off switch.”

In other words, stress undermines our ability to maintain self-control by changing the way our brains work.

The researchers found that the effects of stress were also visible in the brain. The stressed participants’ brains exhibited altered patterns of connectivity between regions including the amygdala, striatum, and the dorsolateral and ventromedial prefrontal cortex, which is what reduced individuals’ ability to exercise self-control over food choices. Only some of these changes were associated with cortisol, a hormone commonly linked to stress.

The investigators say that their study indicates that even moderate levels of stress can impair self-control.

They also observed a good deal of variation in the degree to which stress affected individuals in the study, so it will be important for ongoing research to investigate why some people are more resilient than others.

Do you think stress affects you ability to make good choices? What do you do to banish stress from your life?