Your gut and metabolism are linked – here’s what to eat to help both

The question is: can a healthier gut make your metabolism healthier too? To better understand this vital relationship and how diet can support it, we spoke to Claire Barnes, a nutritionist and founder of The Happy Nutrition Co., and Dr Megan Rossi, a gut health specialist and founder of The Gut Health Doctor and Smart Strains.

Next, discover 10 ways to speed up your metabolism ad find out if you can lose weight just by exercising.

Bowl of colourful healthy salad with avocado

Why is our gut important?

The gut is where the many processes of digestion take place. This includes the breakdown of easily digested foods in the small intestine, metabolism of more complex foods in the large intestine, and filtration of toxins by the liver, which is one of the gut’s ‘solid organs’ along with the pancreas and gallbladder.

What you might not know is that the gut does lots of other things too.

“It is so much more than a digestive organ – it’s the central hub for your overall health,” says gut expert, Dr Rossi.

“Often referred to as the ‘second brain’, your gut is around nine metres long and houses trillions of bacteria (collectively known as your gut microbiota), which influence everything from digestion and immunity to mood.”

“Around 70% of your immune system lives in your gut, and each strongly influences the other through the gut-immune connection. So, if your gut is in good shape, your immune system tends to be more resilient, too,” she adds.

“Research has shown that gut health and mental wellbeing are strongly linked. Diets rich in diverse plants, fermented foods and extra virgin olive oil – like that of the Mediterranean diet – have been shown to support better mood and cognitive health.”

To get to know your gut and its many roles, try reading Gut by Giula Enders.

What is metabolism?

Metabolism is everything the body does to break down food and convert its molecules into useful forms – notably including digestion in the gut.

The process can be divided into two parts; catabolism comes first, as foods such as carbohydrates and proteins are broken down to produce things we need like glycogen and amino acids. Later, anabolism uses that good stuff to build and repair the body.

Not all of the food we eat is metabolised. Much of what our bodies don’t use in this way is formed into faeces in the lower intestine and eventually exits the body.

Some people naturally metabolise food faster than others. Those whose bodies do this quickly can be said to have a fast metabolism, while the opposite is true of those with a slow metabolism.

How much energy we use in our daily activities affects the speed of metabolism, but it is also strongly influenced by our basal metabolic rate (BMR). This is the rate at which our bodies burn calories while at rest. BMR is determined by some factors we can’t control, like age and genetics, and others that we might be able to influence such as muscle mass and general activity levels.

Metabolism uses up our stores of glycogen and fat to give us energy, so it has an effect on weight and body composition.

Which foods help the gut and metabolism?

Plentiful plants

“Eating 30+ different plant foods a week (including fruit, veg, herbs, wholegrains, nuts and seeds) supports a more diverse gut microbiome, which is associated with better metabolic health, immunity and mood,” says nutritionist, Claire Barnes.

“The fibre from plants feeds your beneficial bacteria and helps keep blood sugar stable.”

Fermented foods

Not only do good bacteria cause fermentation and contribute flavour, they also ramp up the nutritional benefits. As Barnes puts it:

“Live cultures found in yoghurt, kefir, sauerkraut, kimchi and kombucha can help restore and maintain a healthy balance of gut bacteria. These beneficial microbes play a role in nutrient synthesis, inflammation control and even fat storage.”

Prebiotics

A prebiotic is something that we can’t digest but which feeds gut bacteria and helps them flourish. “They’re found in foods like onions, garlic, leeks, asparagus and slightly-green bananas,” says Barnes.

“Prebiotics encourage the production of short-chain fatty acids (SCFAs) which play a role in energy metabolism and inflammation reduction.”

Whole foods

“While processed foods – which are high in sugar and refined flour – get absorbed quickly and leave little work for your gut bacteria, whole foods require more breakdown by the microbiome,” says Barnes.

“This leads to a more active and beneficial microbial population and less over-absorption of calories.”

There’s plenty of inspiration to be found in our whole food recipes.

Consistent protein, fat and fibre

It's important to avoid foods that impair the metabolism, such as bingeing on sugar and ultra-processed foods (UPFs).

“Instead, regularly eating a combination of protein, fat and fibre supports blood sugar stability, energy levels and satiety,” says Barnes.

“It prevents the crash-and-crave cycle that leads to poor food choices and metabolic disruption.”

How does the gut affect metabolism?

If you’re aiming to lose weight healthily, it could be helpful to consider the relationship between your gut and metabolism.

According to Dr Rossi, the interaction between the two can be broken down into three main mechanisms:

Energy extraction: “Microbes in the gut hunt for undigested food and turn it into energy – which can be stored as fat. The thing is, certain microbes are better at this than others, and too many of the wrong types may lead to excess calorie absorption.”
Energy regulation: “Your microbes are linked with genes in your body that are related to energy distribution. Plus, they can affect fat and glucose production, which can be stored in your liver.”
Appetite and cravings: “Gut microbes might influence your taste preferences and therefore the calorie density of your food, as well as impacting your mood, which ultimately can influence your food choices. For example, if you’re experiencing low mood you might be more likely to reach for the chocolate bar for a dopamine hit.”

Clearly, microbes are key to the relationship between gut and metabolism – but how can we ensure these tiny lifeforms are working to our benefit?

Will taking probiotics help you lose weight?

Many of our gut microbiota – the bacteria in the gut – do helpful things. For example, bacteria in the bacteroides family are useful for breaking down complex carbs and sugars. We call good bacteria like these ‘probiotics’.

“Those with more diverse gut microbes have been shown to have healthier body weights, but it’s important to note that our understanding of probiotics and how they work has evolved over the past decade,” says Dr Rossi.

“When it comes to probiotics, more does not always equal better (different strains can even compete with each other, disrupting their efficacy), and much like you wouldn’t take a vitamin D supplement to treat an iron deficiency, you need the right probiotic strain for the specific issue you’re targeting.”

Barnes emphasises the importance of pairing gut-healthy foods with a metabolism-healthy lifestyle – especially around meal times.

“Eating at consistent times supports your circadian rhythm, helps your digestive system prepare in advance and can reduce unnecessary snacking,” she says.

“Post-meal, a simple 10-15 minute walk improves blood sugar response, supports digestion and can help reduce inflammation.”

According to Barnes, taking a moment to relax before you eat can also assist the metabolic process.

“Eating in a calm state supports optimal release of digestive enzymes and stomach acid,” she says.

“Just 1-2 minutes of deep breathing before a meal, and chewing slowly and thoroughly, can significantly improve digestion and nutrient absorption.”

So, does your gut impact your metabolism?

In short, yes, it's correct to say that your gut does impact your metabolism.

“You can’t separate gut health from metabolic health – they’re deeply intertwined, and supporting one inherently supports the other,” says Barnes.

“In clinic, I usually begin by supporting the gut because this often improves everything else, including energy, digestion, mood and cravings.”

As we’ve seen, there are plenty of ways to support the gut and the metabolism, from eating whole foods, prebiotics and fermented foods to taking on healthy bacteria called probiotics and tweaking your habits around mealtime.

If you’re interested in your metabolism because you want to lose weight in a sustainable way, remember that it’s often best to avoid extreme or restrictive diets. Our gut feeling is that it’s better to make positive tweaks to diet and lifestyle that you can stick to long-term.

Your gut and metabolism are linked – here’s what to eat to help both

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