Summary This paper examines the effects of stress on the neuroendocrine production of cortisol and links this to potential changes in food choice, mood and bodyweight. Animal and human studies suggest that stressful conditions can result in low mood, increased energy intake, particularly from fatty acids and non-milk extrinsic sugars (NMES), and potential changes in bodyweight. With current unsustainable rises in obesity in the Western world, tackling predictors of weight increase remains a primary target for intervention. In a longitudinal naturalistic study of 71 healthy women, we found an increase in cortisol secretion during a period of chronic stress to be strongly correlated with changes in food choice and increased energy consumption, as well as an increase in intake of saturated fatty acids and NMES. This resulted in an increase in bodyweight. We also found that anxiety and depression increased significantly during the stress period; however, we could find no correlation with mood, food choice or energy intake. Furthermore, we found that women with a body mass index (BMI) on the higher side of ‘healthy’, who experienced a significant increase in cortisol secretion under chronic stress, were more vulnerable to increases in bodyweight than women with lower BMIs and a smaller increase in cortisol secretion. Further research is needed to investigate whether cognitive behavioural/remedial therapies to reduce the impact of stress can help to minimise changes in diet, bodyweight and mental health.