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Meat & microbes: the truth about the carnivore diet

4 August 2025

By The Gut Health Doctor Team

Dr Megan Rossi in a lab looking through a microscope

Social media “meatfluencers” have propelled the #carnivorediet back into the spotlight, claiming benefits which range from weight loss and mental clarity to reduced inflammation and curing gut issues. With solely meat (including fish) and low-lactose dairy products on the menu, this diet is very high in protein, but low in carbohydrates – fibre included (remember fibre is a type of carb). So, with that in mind, is prioritising meat really the answer to better gut health, or overall wellbeing?

We know the gut plays a central role in everything from brain function and immunity to hormone balance. This means the meat vs plant debate extends far beyond digestion, but it can impact almost all other areas of your health too. In fact, research shows that what you eat today can shape your health for years to come…

The appeal of the carnivore diet largely lies in its associated health claims. Many loyal followers will report that they’ve “fixed” their gut by embracing a meat-only approach. While it’s true that some might feel initial relief from gut symptoms in the short term, it can have a detrimental impact on gut health in the longer term. To understand why, we need to unpack what’s really happening in the gut, why carnivore diets can seem effective, and what the science says about restrictive versus inclusive eating for your gut, mind and overall wellbeing.

Quick wins: why carnivore diets can feel great initially

Removing plant triggers in sensitive guts

If you’ve got irritable bowel syndrome (IBS) or another type of functional gut disorder like functional bloating, which can present as a ‘sensitive’ gut, certain plant compounds (including many types of fibre, like FODMAPs) can trigger uncomfortable symptoms. This is because when your gut microbes break down fibre, alongside beneficial chemicals, they also produce gas. While this gas is completely normal and inert, if you have a sensitive gut, the extra pressure from the gas can trigger your gut’s nervous system, producing symptoms.

With this in mind, it’s no surprise that some people might feel better, at least initially, by cutting out a wide range of plant foods. But here is the thing. Removing them completely, as in the case of a carnivore diet, means your gut microbes miss out on being fed some of their favourite foods. Over time, this may also make your gut more sensitive, so even small amounts of plant foods can feel overwhelming. It’s a bit like avoiding exercise. Over time, you lose muscle and cardiovascular fitness, and then when you do try exercise again, it can feel really hard and painful for your muscles, at least to begin with. If this is something you’re experiencing, while reintroducing plants can feel a little uncomfortable at first, with the right guidance, gradual reintroduction can help build up your gut’s tolerance and support your long-term health. Check out the tips at the end of this blog to discover how to train your gut to become fibre fit.

Swapping ultra‑processed foods (UPFs) for clean meat

Some people turn to a carnivore diet after years of relying on ultra-processed foods — think ready meals, protein shakes, packaged snacks and sugary drinks. Stripping out these foods and focusing on minimally processed options (even if exclusively meat-based) can lead to improvements in inflammation, digestion and weight management. But let’s be clear — it’s not the meat itself that’s making the difference. It’s the removal of the heavy reliance on the ultra-processed foods that’s likely behind those early wins.

It’s important to be aware that these benefits associated with a carnivore diet tend to be short-lived. To continue experiencing these benefits (and many more) in the medium to long term, the research highlights that including plants in your diet is crucial.

What the science says about meat and your microbiome

Meat-only diets don’t just remove fibre and plant-based nutrients, but they actively shift the makeup of your microbiome. In a 2020 study, participants following a meat-heavy diet reported an increase in bile-tolerant microbes (which are linked to inflammation) and a reduction in beneficial butyrate-producing species that help maintain gut lining strength and regulate the immune system. Plus, a study published earlier this year of nearly 10,000 people in Sweden found that a higher intake of red, processed meat was linked to lower gut microbial diversity, and it was associated with higher fasting glucose and insulin levels, too.

Over time, this loss of microbial diversity and function can affect more than just digestion; it’s also connected to mood, hormone balance, immunity and metabolic flexibility, just to name a few. Plus, it can affect your cravings, too. Research from the University of Toronto found that people who were told to avoid chocolate for a week ate significantly more when given the chance than those who hadn’t restricted themselves. This psychological response, known as the ‘forbidden fruit effect,’ is a key reason why a restrictive approach often leads to bingeing, with many people explaining they feel out of control around certain foods.

In contrast, dialling down your meat intake to moderate amounts as part of a plant-diverse diet isn’t just a middle-ground approach; it’s evidence-based. One of the largest nutrition studies to date, the PREDIMED trial, found that a Mediterranean-style diet, which includes both plants and moderate meat intake, supports gut, heart and metabolic health.

Plus, Dr Megan Rossi’s own research, published in the journal Nutrition, Metabolism and Cardiovascular Disease, looked at the link between protein and fibre in the digestive process. It found that the more plants you eat with your meat, the lower the risk of your gut microbiome releasing chemicals that are linked to negative health outcomes (such as trimethylamine N-oxide, which is associated with metabolic and heart disease). This is because when you eat a large portion of meat in one sitting (think those big steaks when you’re out for dinner), it’s more likely to overwhelm your upper intestine’s ability to digest it all. This means some of it may travel through to the lower intestine, where the gut bacteria ferment it, and a more ‘aggressive’ inflammatory gut microbiota can develop. However, if you give the gut bacteria plenty of plants to ‘eat’ alongside your meat, they’ll digest the fibre and leave the protein from the meat, avoiding those potentially toxic by-products produced by the bacteria digesting the meat. So it’s not about cutting out meat completely (unless you want to, in which case check out this blog), but about balance. Consider the type, how much you eat, and what else is on your plate, too.

Long‑term well-being demands plant diversity

Quick fixes might bring short-term relief, but lasting gut health is built on resilience, and that starts with plant diversity. Plants are the main fuel source for your gut microbes, which play a crucial role in everything from digestion and immunity to mood and metabolism.

A 10,000-person study found that eating 30 different types of plants each week was linked to richer, more resilient microbiomes – a marker associated with better long-term health.
On the flip side, a reduction in microbial diversity is associated with chronic inflammation, immune dysregulation, and mental health.

The goal isn’t only to focus on plants, but to incorporate 30+ plant points a week, including the Super Six (fruits, vegetables, legumes, whole grains, nuts, seeds, herbs, and spices). This gives you, your gut and your body the broadest support. Need some tasty inspiration? Our free recipe hub is packed with simple, plant-powered recipes to help you hit your target with ease.

Smarter strategies for gut and overall health

You don’t have to give up meat, but focusing on adding variety from plants is essential for sustained well-being. Here’s how:

1. Eat inclusively — aim for a mix of lean meats alongside a diverse variety of plant foods to nourish your microbes and their clever connections. If you’re looking for inspiration, we recommend starting with this gut: immune supporting chicken soup or this plant-powered pad thai fakeaway.

2. Take it slowly — if you’ve previously taken a restrictive approach, reintroduce plants gradually, and make sure you stay hydrated (fibre needs water to work its magic). Check out this blog on becoming fibre fit.

3. Minimise ultra-processed foods — regardless of whether they’re meat or plant-based, early research from Megan and Amy’s team at King’s College London indicates that the emulsifiers found in many UPF have been linked to negative gut side-effects in those with Crohn’s. That doesn’t mean you need to cut them all out, but being mindful of UPF intake could make a difference while still maintaining a balanced, nutritious diet.

4. Log small wins — building new habits takes time, so it’s important to acknowledge your progress along the way. For example, if your goal is to eat 30 different plants each week (although I wouldn’t stop there!), start by adding just one new plant-based food each week and gradually increasing over time. A simple, budget-friendly way to boost your intake is to include mixed plant varieties (bags or cans), such as fruits, vegetables, beans, nuts, and seeds. This makes increasing your diversity hassle-free.

Takeaway

Right now, going meat-only might feel like a fix, especially if it helps you escape plant triggers or ultra-processed foods. But it’s a short-term trick, not a sustainable solution. For true, lasting health, your gut (and your body) thrive on variety — both plant-based and animal foods have their roles.

Feeling unsure or stuck? Consider personalised support. Registered dietitians at The Gut Health Clinic can guide you through tricky symptoms or the reintroduction of plans.

Illustration of gut with micro bacteria and a quiz sheet

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