 There is evidence that our subjective experience of the world is strongly influenced by our metabolic state, the status of our bodys energy reserves and level of hunger. Hormones that regulate appetite, food ingestion and body weight apparently also exert their action on neuroanatomical circuits involved in the generation of psychological states. Previous research indicates that an individuals metabolic state may influence their susceptibility to and experience of anxiety. Conversely, stress can also modulate appetite and body weight regulation. There are many clinical implications of the bidirectional relationship between stressanxiety and metabolic stateenergy regulation but two of the most important ones are obesity and eating disorders. In terms of obesity, the high recidivism after successful weight loss underscores the limited use of caloric restriction to treat obesity. It is unknown whether dieting fasting increases anxiety, which eventually may undermine an individuals motivation to restrict food intake. Research shows that anxiety can increase appetite and exacerbate the physical and psychological manifestations associated with hunger. However, there is a paucity of experimental data establishing whether the metabolic changes associated with fasting influence the experience of stress and possibly, an individuals ability to continue dieting for an extended period of time. In the setting of both obesity and anorexia nervosa, the levels of metabolic hormones are different to those found in people of normal body weight. It is therefore likely that the activation of brain regions associated with energy and body weight regulation is abnormal. Many of these brain regions are also involved in the control of anxiety responses. The fact that there is a high comorbidity between anorexia nervosa and anxiety disorders indicates the potential contribution of metabolic states to the perception of stress. 