When someone starts to feel stressed or anxious, their body begins to release stress hormones. These hormones activate the sympathetic nervous system and trigger the body’s fight-or-flight response.
The fight-or-flight response is an instinctive reaction that attempts to keep people safe from potential threats. It physically prepares the body to either stay and fight a threat or run away to safety.
This sudden surge of stress hormones has several physical effects. For example, research suggests that one of the hormones — corticotropin-releasing factor (CRF) — affects the digestive system and may lead to the suppression of appetite.
Another hormone, cortisol, increases gastric acid secretion to speed the digestion of food so that the person can fight or flee more efficiently.
Other digestive effects of the fight-or-flight response can include:
This response can cause additional physical symptoms, such as an increase in breathing rate, heart rate, and blood pressure. It also causes muscle tension, pale or flushed skin, and shakiness.
Some of these physical symptoms can be so uncomfortable that people have no desire to eat. Feeling constipated, for example, can make the thought of eating seem very unappetizing.