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Is there a link between gut health and weight loss?
Written byH&B editorial team
Reviewed byMadalena Vieira Costa
Could making pals with friendly bacteria help you lose weight? And how does your body make weight loss hormones? Digest it all with help from our nutritionist
Summary
1What does gut bacteria do for you?
It helps you digest food, supports your immune system, manages your metabolism and more...
2Is gut health linked to weight?
Microbes may alter the way we store fat, how we balance our blood glucose levels...
3How can you support natural GLP-1 levels?
Improving gut health and fibre intake can help increase your body's natural GLP-1 activity...
Fun fact: there are just as many bacteria in your body as there are your own cells.1 That might make you feel a bit weird, but it shows just how important it is to take care of your friendly microbes. From the gut-brain axis to weight management, we're learning more about the benefits of a healthy gut every day. With help from H&B nutritionist Madalena Vieira Costa, learn how our body produces GLP-1 and how your friendly bacteria may play a part in reaching your weight goals...
What does gut bacteria do for you?
Deep down in your large intestine, there are around 39 trillion microbes – mostly bacteria.2 Collectively, they’re known as your microbiota and help you:3
- digest food
- maintain a normal immune system
- produce enzymes
- manage your metabolism
But they can only do this if your microbiome (the ‘community’ of microbes, their genes and the chemicals they produce) is in balance. If it’s not, you might notice signs like digestive issues, low energy or weight gain.3,4 The best way to do this is by getting friendly bacteria into your diet, so they can join the community and get to work! More on this later.
Is gut health linked to weight?
One study on obese and lean sets of twins showed that lean twins have a more vibrant and diverse microbe community, while twins with obesity have less diverse microbes.5 Microbes may alter the way we store fat, how we balance our blood glucose levels and how we respond to hormones that signal hunger and satiety.6 All of these can affect our body composition.
How does GLP-1 play a part?
You might have heard of GLP-1 (short for glucagon-like peptide-1) when talking about medications like Mounjaro or Ozempic. It's a hormone that’s produced in our gut, which plays a role in appetite and regulating blood sugar levels.7
When we eat, our body turns the food into glucose – the body’s main source of energy. Our body can produce two hormones in response: glucagon to raise blood sugar or insulin to lower it.8 GLP-1 plays a role in this process.7 According to Madalena, “it also slows stomach emptying and promotes satiety”.9
In some cases, like in type 2 diabetes, this process is disrupted. People might be prescribed a GLP-1 agonist (a medication that affects GLP-1 levels) to ‘kickstart’ it. These are a kind of prescription-only medication which works by affecting appetite.
How can you support natural GLP-1 levels?
If you’re on a journey to support your gut health, it might be useful to try and increase your natural GLP-1 levels.
Improving gut health and fibre intake can modestly increase your body’s natural GLP-1 activity.10
These diet and lifestyle changes won’t replicate the effects of GLP-1 agonists on a medicinal level – so make sure you’re combining them with GLP-1 agonists if recommended by your doctor. Let’s dive into the details...
Biotics and the gut microbiome
Fermentable dietary fibres are a major source of short-chain fatty acids (SCFAs), which are produced by gut bacteria. Previous reports have demonstrated that SCFAs like acetate and propionate help stimulate GLP-1 secretion.11 So, how can we get more of these good bacteria and fibres into our gut? Great news: many of them can come from your diet.
Fermented foods
Fermented foods contain biotics and eating them is an easy way to get some good microbes into your gut. Just be sure to check for ‘live’ versions on the packaging. Look out for foods like:
- sauerkraut: a German pickled cabbage dish. Buy this fresh from the fridge section
- miso: a Japanese paste made from fermented soybeans. Add to ramen, make miso soup or our high-protein miso beans
- tempeh: a plant-based protein made from fermented soybeans
- apple cider vinegar: ideal for salad dressings
- kefir: a sour, yoghurty drink made from fermented milk
- kombucha: a tangy, naturally fizzy drink made from fermented tea
- yoghurt: look for natural yoghurt or Greek yoghurt
Can biotics help with weight loss?
It’s hard to say for sure. Certain probiotic interventions (particularly combinations of strains within Lactobacillus and Bifidobacterium) have been associated with outcomes related to weight management, but more research is needed.12 There’s emerging evidence suggesting they:
Some probiotic blends may affect the gut by boosting beneficial compounds made by gut bacteria, known as short chain fatty acids (SCFAs). These molecules can play a role in keeping the gut barrier strong and encourage a healthy inflammatory response.12,13
Research suggests that an increase in SCFA production may encourage cells called L-cells to release GLP-1.14 This is a promising area of science, but more robust studies are needed before the benefits are fully confirmed.14
More research is needed here, but “probiotics may enhance bile acid metabolism”.14 What’s so important about that? Well, it can encourage GLP-1 production.14
Fibre and the gut microbiome
Fibre might feel like something your parents go on about. But it helps maintain a happy environment where friendly bacteria can thrive – and 96% of us aren’t getting enough of it.15,16
“When you eat fibre-rich foods, your gut bacteria breaks down the fibre in the colon, producing short-chain fatty acids. These short-chain fatty acids activate specific receptors on L-cells and trigger the release of GLP-1,” says Madalena.
“An imbalanced microbiome (dysbiosis) increases gut inflammation, which can damage L-cells and therefore reduce GLP-1 secretion. By contrast, a healthy microbiome helps maintain gut lining integrity and supports hormone release.”12,14
You can add extra fibre to your diet by:
- swapping white bread, pasta and rice for wholegrain
- leaving the skin on fruit and veg (think potatoes, carrots and even kiwis)
- sprinkling nuts and seeds into your cereal, onto porridge or through your usual bakes
- adding beans, chickpeas or lentils to curries and stews
For a full run-down and extra tips, check out our ultimate guide to fibre.
The final say
GLP may not be as easy as one, two, three... but hopefully you’re a little more clued up on how it works. Why not take five minutes to do something good for your friendly bacteria? That could be grabbing a fibre-packed snack or learning about probiotics from a gut health doctor.
Disclaimer - This article provides informational advice and is not a substitute for medical care. Working with experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.
1. Sender R, Fuchs S, Milo R. Are We Really Vastly Outnumbered? Revisiting the Ratio of Bacterial to Host Cells in Humans. Cell [Internet]. 2016 Jan 28 [cited 2025 Oct 10]; 164(3): 337-40. Available from: https://www.sciencedirect.com/science/article/pii/S0092867416000532
2. Koh A, Bäckhed F. From Association to Causality: the Role of the Gut Microbiota and Its Functional Products on Host Metabolism. Mollecular Cell [Internet]. 2020 May 21 [cited 2025 Oct 10]; 78(4): 584-96. Available from: From Association to Causality: the Role of the Gut Microbiota and Its Functional Products on Host Metabolism - ScienceDirect
3. Valdes AM et al. Role of the gut microbiota in nutrition and health. BMJ [Internet]. 2018 Jun 13 [cited 2025 Oct 10]; 361. Available from: https://www.bmj.com/content/361/bmj.k2179
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5. Turnbaugh PJ et al. A core gut microbiome in obese and lean twins. Nature [Internet]. 2009 Jul 22 [cited 2025 Oct 10]; 457(7228): 480-84. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC2677729/
6. Han H et al. From gut microbiota to host appetite: gut microbiota-derived metabolites as key regulators. Microbiome [Internet]. 2021 Jul 20 [cited 2025 Oct 10]; 162. Available from: https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-021-01093-y
7. Collins L, Costello RA. Glucagon-Like Peptide-1 Receptor Agonists. StatPearls [Internet]. 2024 Feb 29 [cited 2025 Oct 10]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551568/
8. Endocrine Society. Pancreas Hormones [Internet]. Endocrine Society [reviewed 2022 Jan 24; cited 2025 Oct 10]. Available from: https://www.endocrine.org/patient-engagement/endocrine-library/hormones-and-endocrine-function/pancreas-hormones
9. Drucker DJ. GLP-1 physiology informs the pharmacotherapy of obesity. Molecular Metabolism [Internet]. 2022 Mar [cited 2025 Oct 10]; 101351. Available from: https://www.sciencedirect.com/science/article/pii/S2212877821001988
10. Wu S et al. A New Dietary Fiber Can Enhance Satiety and Reduce Postprandial Blood Glucose in Healthy Adults: A Randomized Cross-Over Trial. Nutrients [Internet]. 2023 Oct 27 [cited 2025 Oct 10]; 15(21): 4569. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10648557/
11. Hira T, Trakooncharoenvit A, Taguchi H, Hara H. Improvement of Glucose Tolerance by Food Factors Having Glucagon-Like Peptide-1 Releasing Activity. Int J Mol Sci [Internet]. 2021 Jun 21 [cited 2025 Oct 10]; 22(12): 6623. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC8235588/
12. Torres B et al. Use of probiotics in preventing and treating excess weight and obesity. A systematic review. Obes Sci Pract [Internet]. 2024 Jun 19 [cited 2025 Oct 10]; 10(3): e759. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11187407/
13. Cao N, Zhao F, Kwok LY, Wang H, Sun Z. Impact of probiotics on weight loss, glucose and lipid metabolism in overweight or obese women: A meta-analysis of randomized controlled trials. Current Research in Food Science [Internet]. 2024 [cited 2025 Oct 10]; 100810. Available from: https://www.sciencedirect.com/science/article/pii/S2665927124001369?via%3Dihub
14. Zeng Y, Wu Y, Zhang Q, Xiao X. Crosstalk between glucagon-like peptide 1 and gut microbiota in metabolic diseases. mBio [Internet]. 2023 Dec 6 [cited 2025 Oct 10]; 15(1): e02032-23. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10790698/
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