When most people think of the gut, they picture it as a simple digestive machine. Something that breaks down food and keeps things moving.

But science is now showing us that your gut isn’t just about digestion. It’s a hidden command centre, quietly coordinating key functions across your entire body.

It’s where your energy, mood, metabolism, and even your long-term health are shaped.

Over the last decade, researchers have begun to call the gut the 'second brain' or 'control centre' of the body. And once you understand how it works, you’ll start to realise why so many modern health issues actually start in the gut.

Here’s how your gut pulls the strings behind the scenes:

1) Your gut controls your energy levels

Inside your gut live over a trillion microorganisms (tiny little things) like bacteria, fungi, viruses, and more. Collectively, these are known as your gut microbiota.

That’s completely normal, and they don’t just sit there passively. These microbes actively break down nutrients you wouldn’t be able to digest on your own, particularly complex carbohydrates and dietary fibres.

When they do this, they produce short-chain fatty acids (SCFAs), things like butyrate, acetate, and propionate. These SCFAs aren’t simply waste; they are absorbed into the bloodstream and used as a direct energy source by your cells, playing a crucial role in how efficiently your body produces and uses energy.

If your gut microbiota is imbalanced (what scientists call dysbiosis), your body may struggle to produce enough SCFAs. Over time, this can mean lower energy availability, poor nutrient absorption, and even contribute to issues like chronic fatigue.

2) Your gut shapes your mood

The phrase 'gut feeling' is more literal than you might think.

Your gut and brain are constantly talking to each other through a complex network called the gut-brain axis. This isn’t just metaphorical, it’s a real, physical connection made up of nerve pathways, hormones, and chemical messengers between the two.

The vagus nerve is the main connection between the gut and brain, and interestingly, around 80% of the information flows from the gut to the brain, not the other way around. That means what’s happening in your gut can heavily influence how your brain feels.

On top of that, your gut is a major production site for key neurotransmitters (chemical messengers):

- 90–95% of your serotonin (the 'feel-good' hormone) is made in your gut.

- It also helps regulate dopamine (motivation & reward) and GABA (calm & relaxation)

When your microbiome is balanced, these chemicals help you feel positive, motivated, and resilient to stress. But when your gut is inflamed or imbalanced, neurotransmitter production can dip, contributing to low mood, anxiety, irritability, and brain fog.

‍3) Your gut regulates your metabolism

One of the lesser-known roles of your gut is how it impacts your metabolism, meaning how efficiently you burn calories, store fat, and regulate your weight.

Different types of gut bacteria extract energy from food in different ways. For example:‍

- Firmicutes bacteria are more efficient at extracting calories from complex carbohydrates.‍

- Bacteroidetes bacteria are less efficient at energy extraction.

People with a higher ratio of Firmicutes to Bacteroidetes tend to absorb more calories from the same amount of food. Over time, this imbalance has been linked to weight gain and fat storage.

But it doesn’t stop there. Your gut microbiota also affects hormones and molecules that control your appetite and fat-burning:

SCFAs produced by gut bacteria stimulate the release of GLP-1 and PYY, hormones that signal fullness and reduce appetite. They also improve insulin sensitivity, helping your body control blood sugar and reduce fat storage.

If your gut is out of balance and SCFA production drops, you may feel hungrier, store more fat, and struggle with a sluggish metabolism, no matter how healthy your diet is.

So what does this all mean?

Your gut isn’t just a digestive tube, it’s the hidden control centre of your body.

Your gut microbiome could be the real key driver behind your energy, mood, metabolism, and even long-term weight management.

When your gut microbiome is thriving, you’re more likely to feel:

- Energised

- Positive and resilient

- Lean and metabolically healthy

But when it’s damaged, everything from fatigue and anxiety to weight gain and chronic inflammation can start to creep in, no matter how 'healthy' your lifestyle looks on paper.

Sources:

Microbial Degradation of Complex Carbohydrates in the Gut (Gut Microbes)

The Microbiota-Gut-Brain Axis (Physiological Reviews)

An Obesity-Associated Gut Microbiome with Increased Capacity for Energy Harvest (Nature)

Short-Chain Fatty Acids in Control of Body Weight and Insulin Sensitivity (Nature Reviews Endocrinology)