Yes, it increases cortisol levels. Anxiety is a mental disorder characterized by a person’s fear of certain situations or objects. The anxiety can be generalized or specific to a situation. These feelings may range from minor, such as feeling uneasy, to intense, such as panic attacks. For some people, it can cause them to overeat and gain weight or avoid eating at all in order to stay thin. Overthinking often causes weight gain because the worry leads to an increase in cortisol levels. Cortisol is a stress hormone that can lead to more fat around the stomach area than anywhere else on the body.