Here’s what Professor Hallux has to say:
It’s an odd expression isn’t it? Don’t worry you don’t really have actual butterflies in your stomach! It’s just the name given to the jittery feeling you can get when you’re a bit nervous.
Here’s what’s going on. When an animal in the wild is in danger, its body releases a burst of a hormone called adrenaline – this causes some of the blood in the body to be diverted to the muscles. This means the muscles can then help the animal to fight or get out of there! It’s known at the ‘fight or flight’ reflex.
Now when something makes you anxious – such as a test or big footy match – the same thing occurs. Your brain prepares you for action by releasing adrenaline which diverts blood to your muscles and away from less essential organs like your stomach, which is why it feels strange!
It’s also the reason why you might not feel hungry when you’re worried. But it’s only temporary and when the excitement has passed your tummy – and appetite – should get back to normal.