Why do we get ‘Butterflies in the stomach’?

“Butterflies in the stomach” is the fluttery, nervous sensation many people experience before a job interview, public speech, exam or even at the start of a new romance. As academic Amy Loughman explains, it’s a charming way to describe a physical response that is actually part of the body’s survival system. Reported by 1News. 

But what really causes this sensation? Why do we feel it in our stomach? And can we control it?

The Body’s Threat Response

The feeling of “butterflies” often comes with other symptoms such as a faster heartbeat, sweating and a heightened sense of alertness. These are signs that your body’s fight-or-flight response has been activated.

This reaction involves the autonomic nervous system — the system that regulates automatic bodily functions. When you perceive a threat, whether physical or social, real or imagined, signals are sent to the brain’s amygdala for emotional processing. If the amygdala interprets danger, it alerts the hypothalamus, triggering a chain reaction throughout the body.

The adrenal glands, located above each kidney, release adrenaline and noradrenaline into the bloodstream. These hormones increase heart rate, raise blood sugar levels and direct blood flow toward muscles, preparing the body to either fight or flee.

Why the Stomach Gets Involved

When survival mode kicks in, digestion becomes a lower priority. The body reduces blood flow to the stomach and intestines and temporarily slows the gut’s rhythmic movements, known as peristalsis.

At the same time, the autonomic nervous system communicates with digestive organs through the vagus nerve — a key nerve running from the brainstem down through the body. This nerve constantly sends signals between the brain, heart and digestive system.

Although there is no single confirmed cause of the fluttering sensation, it is likely linked to the temporary pause in gut activity and the signals sent to the brain through the vagus nerve.

A “Gut Feeling”

The sensation of butterflies is technically a “gut feeling,” and it highlights the close connection between the brain and the digestive system. This relationship, known as the gut-brain axis, allows the body to share signals about stress, mood, digestion and appetite.

So the next time you feel those nervous flutters, remember — it’s your body’s ancient survival system responding to a perceived challenge, even if that challenge is just giving a presentation or meeting someone new.

Gut microbes are one part of this complex communication system. It’s tempting to think that the action of microbes is what causes the fluttery, butterfly feeling, but it’s unlikely to be that simple.

Microbes are, well, microscopic, as are the actions and changes they undergo from moment to moment. There would need to be coordinated microbial movements en masse to explain the sudden onset of that anxious feeling, like a flock of geese in formation, and there isn’t any evidence that microbes work like that

However microbes have been shown to impact the stress response, with most research so far conducted in mice.

In humans, there is modest evidence from a small study linking microbes with the stress response. This showed that sticking to a microbiome-targeted diet – a diet, rich in prebiotic fibres, designed to feed fibre-loving members of your gut microbiome – could reduce perceived stress compared to a standard healthy diet.

But this single study isn’t enough on its own to definitively tell us exactly how this would work, or if this diet would work for everyone.

How can we manage those nervous bodily feelings?

The first thing to consider is if you need to manage them at all. If it’s a once in a blue-moon, high-stress situation, you might be able to just say “hi” to those butterflies and keep going about your day until your body’s rest-and-digest response kicks in to bring your body back to baseline.

Self-guided techniques can also help.

Mindfully observing your fluttery butterflies may help you notice subtle cues in your body about how you’re feeling, before you become overwhelmed.

By then moving through any actions in your control – from noticing your breath through to taking the next steps towards the plunge you fear most – you show your brain you can overcome the threat.

Sometimes it can be worth turning to the cause of the anxiety-causing situation itself. Could some extra interview prep (for example) help you feel more in control? Or is it more about reminding yourself of how getting through these situations aligns with your values? Sometimes a shift in perspective makes all the difference.

If anxiety is more frequent or is getting in the way of doing the things that matter to you, try the evidence-based method of “dropping the struggle”.

This means sitting with, instead of trying to fight or resist, anxiety and any other bothersome feelings. You might even thank your mind (and body) for its attempt to help, and for the reminder about what is important to you.

Or you can seek help from a psychologist to ease anxiety (as well as other common mental health struggles) using an evidence-based approach commonly known as ACT or acceptance and commitment therapy. This involves developing skills for living a meaningful life in spite of difficult emotions and situations. It helps people work with, rather than control, tricky thoughts and feelings.