Eli5: Why does anxiety take appetite away and causes stomach to hurt ?


Eli5: Why does anxiety take appetite away and causes stomach to hurt ?

In: Biology


As you become stressed your body prepares to defend itself from physical attack. This means it turns off all the things that aren’t designed to fight or run away. That includes your stomach and digestion. No point wasting energy digesting food if you are going to get attacked by a tiger in the next 5 minutes.

Stress is a survival response.

Stress has not evolved with our growing types and colors of stress.

Your boss is a passive aggressive asshole? Stressful final? Interview that could make your break your career? Your body thinks it’s in actual danger. For all it knows, you need to figure out how to escape an enemy camp so you’re not eaten alive tomorrow.

Your body thinks it needs to focus on you escaping this problem, not on digestion, to save your life.

On top of that, your body is pumping all these chemicals into your blood stream to help you escape a real threat. You will probably feel awful if you’re just sitting around, freaking out, and not out running the bear your body has so kindly prepared you for.

You have two major parts of your nervous system. One of them is the sympathetic system — nicknamed “fight or flight” — which gets all different parts of your body ready for action. It gets activated when your body senses that there could be a danger present, which is often what’s happening when you feel anxious. This activates things like dilating your pupils (to make your vision better!), or making your breathing and heartbeat quicker (getting ready for physical activity!).

The other half of your central nervous system is the parasympathetic — nicknamed the “rest and digest” system. It takes care of all the other stuff your body needs when it’s NOT super active. As the name suggests, it’s for resting your body and digesting your meals! When you’re getting ready to respond to danger — i.e. in fight or flight mode — your body moves its resources AWAY from the rest and digest system. Which is why you lose your appetite. Can’t have you sluggish and digesting a big meal when you need to run away from a tiger! (or a speech in front of 100 people, maybe the modern equivalent of a tiger).

Your digestive system actually also has its OWN nervous system, which is pretty cool but also makes our digestive systems kinda wacky when it comes to stress. Your body releases a special hormone called cortisol when it’s in “fight or flight” mode than can affect your stomach and intestines, which can also sometimes cause them to hurt. It’s probably different for everyone too, because our bodies all react differently to stress and the hormones that we produce!

I would also like to add about the Vagus nerve. It passes from the brain through the neck all the way to the gut. Anxiety affects the Vagus nerve and it in turn affects all the important systems that it controls, such as your throat, stomach, gut, liver, kidneys etc and vice versa.