Role of Gut Health in Weight Management

What if the old adage ‘you are what you eat’ is true in a way that you haven’t even thought of yet? Most of us know that balanced nutrition, along with regular physical activity, adequate sleep, and stress management, are all important factors in achieving and maintaining a healthy weight. But did you know that your gut microbiome can play a role in weight management and overall health, too? Yes, the microbes that eat your food have some influence on the way your body processes calories, stores fat, and more.

What is the gut microbiome?

You have an entire ecosystem of living organisms in your gastrointestinal system. This complex system of roughly 38 trillion microorganisms, known as the gut microbiome, includes bacteria, viruses, fungi, and parasites, and every person’s gut microbiome is totally unique.

The gut microbiome is maintained according to a symbiotic (mutually beneficial) relationship: we provide food and shelter for these organisms in the large intestine, and in turn, the microbiota provide essential services for our bodies, but it doesn’t end with digestion. In fact, gut bacteria are considered essential to your health because they also assist with regulating your immune system, producing vitamins K and B12, and much more.¹

The specifics of how the gut microbiome influences body weight is not clear, but researchers are uncovering more details about how it works all the time.²

What are some of the signs of an imbalanced gut microbiome?

An abundance of “bad” bacteria (called dysbiosis) can have a range of symptoms that may mimic other gastrointestinal ailments, including:

Lower abdominal pain
Poor digestion
Diarrhea
Bloated stomach
Gas pain
Frequent constipation

There is no specific test to screen for gut dysbiosis, but your doctor could order blood tests, stool tests, or breath tests to screen for certain conditions and byproducts of bacterial overgrowth if the results were considered to be of value to diagnosis or treatment choice. If you are found to have a condition that is disrupting your gut microbiome, there are some medical treatments your doctor might recommend, like an elimination diet, round of antibiotics, or for severely diminished microbiomes, even a fecal transplant (where a sample of healthy gut microbiota is transferred to help the damaged bacteria flourish). If you have questions or concerns about the health of your gut microbiome, talk to your Rexall pharmacist.¹

How is my gut microbiome connected to my weight?

There are several ways that your gut health can influence your body size. Here are the main gut-weight connections.

Appetite control
If you think you are hungry more often than the average person, you may have an imbalance of gut bacteria. Certain hormones, such as GLP-1, are produced in the gut and signal fullness to the brain. That is how the GLP-1 receptor agonist weight-reducing drugs we’ve heard so much about recently work. These “satiety” (creating a feeling of fullness) hormones are produced after we eat and rely on bacteria to function normally. Researchers have found that a lack of “good” bacteria can throw off these satiety signals and contribute to overeating, which can lead to weight gain.³
Blood sugar maintenance
The colonies of bacteria interact with the endocrine cells in the lining of your gut too, secreting hormones that regulate blood sugar as well as other functions. Researchers have found that an abundance of certain beneficial types of bacteria can increase insulin sensitivity, which supports reduced blood sugar and a healthier weight. Meanwhile, an overgrowth of less beneficial types of bacteria can trigger insulin resistance, increasing the risk of type 2 diabetes and weight gain.⁴
The side effects of GLP-1 medications are unbearable.
Most people are not too bothered by side effects of these medications. However, some people may experience nausea, vomiting, constipation, and diarrhea.⁶ Usually, these effects occur early in treatment and when the dose is being increased. Often, slower dose increases or reducing the dose can help reduce side effects.⁹
Metabolism
The gut microbiome plays an important role in regulating your metabolism, affecting how your body extracts energy from the food you eat, as well as how it stores fat. Gut microbes work to break down indigestible dietary fibre, creating metabolites that influence energy output and how your body weight is regulated.⁵

Researchers continue to examine how the gut microbiome is connected to weight management, but we have not yet reached a point where we can determine how to influence or change the gut microbiome to help us shed pounds. For now, doctors and scientists recommend people focus on foods and behaviours that contribute to overall gut health, like eating well and moving our bodies, which will in turn support weight loss when it’s needed.²

What factors affect my gut microbiome?

The gut microbiome is often compared to a garden, with different plants that have changing life cycles that can be nurtured by the right nutrients and environment, and harmed by pollutants, weeds, and pests. The bacteria in your gut are influenced by what you eat, the chemicals it’s exposed to, like alcohol and tobacco, as well as certain medications you may take. Other factors, like regularity of bowel movements, play a role too. And a range of conditions including chronic infections, allergies, irritable bowel syndrome (IBS), fatty liver disease, and even chronic fatigue may be indirectly related to gut dysbiosis.¹

If you are trying to shed extra pounds or just trying to improve your digestive health, try these tips to improve and maintain the health of your gut, which may in turn support your weight-loss journey and improve your overall health and well-being:

Eat fibre-rich foods
Healthy gut bacteria need prebiotics in order to thrive. Prebiotics come from the soluble fibre you eat that passes into your large colon where it is fermented. Soluble fibre, also called inulin, is found in many vegetables, nuts, seeds, and grain products. Think apples, onions, lentils and beans. Health Canada recommends that women consume 25 grams of fibre daily and that men get 28 grams per day. Not sure if you’re getting enough? Ask your Rexall pharmacist or your family doctor if a fibre supplement might be right for you.⁶
Cut back on processed meals
While you’re loading up on prebiotic-loaded, fiber-rich foods, it’s important to eat fewer processed, fast foods because these are typically high in simple carbohydrates that are quickly and easily broken down in the small bowel. In short, they don’t feed the good bacteria of your gut microbiome, which supports weight maintenance. What’s worse, some research has shown that a diet high in ultra-processed foods such as sausage, mass-produced bread, and instant noodles, can disrupt and alter the microbes in your gut.
Exercise regularly
Going for bike rides, hitting the gym, and attending yoga classes are all good for your gut and general health. Regular, moderate-intensity exercise increases blood flow to the digestive system, reduces inflammation, and enhances microbial diversity. And researchers have found that how long you move your body for, not how hard you work out, is most important for improving gut bacteria. Aiming for the Health Canada movement guidelines of 150 minutes per week will do your whole body good, including your gut microbiome.⁷
Try fermented foods more often
Fermented products are made when good bacteria are added or found naturally in the food. These live bacteria are a source of probiotics, which nourish your gut. According to the Dietitians of Canada, some of the best fermented foods for gut health include kefir (a fermented milk drink), sauerkraut (a fermented cabbage condiment), kombucha (a fermented drink traditionally made with tea), miso (a Japanese fermented soybean paste), and yogurt. When shopping for fermented foods, look for phrases like “live and active cultures” and “fermented” on the packaging. Although there is no recommendation for how much fermented food you should eat or drink each day, incorporating them into your meals and snacks more often will help strengthen your gut microbiota and boost digestive health.⁸
Add a probiotic and/or prebiotic supplement
If you are unsure of whether you are getting enough from your meals and snacks, a supplement is another way to support the health of your gut microbiome. Probiotic and prebiotic supplements come in pills or powders that can be stirred into drinks or smoothies.¹ If you are taking an antibiotic, talk to your Rexall pharmacist about whether it may be beneficial to start a probiotic supplement once your course of this medication is finished. They can also offer advice on which products might be right for you.

If you have any questions about the health of your gut microbiome, what you can do to support it, or how it might be related to your weight management, talk to your Rexall pharmacist.

1. Cleveland Clinic. Gut Microbiome. 2023. https://my.clevelandclinic.org/health/body/25201-gut-microbiome. Accessed March 3, 2026.
2. Koutoukidis DA, Jebb SA, Zimmerman M, et al. The association of weight loss with changes in the gut microbiota diversity, composition, and intestinal permeability: a systematic review and meta-analysis. https://pmc.ncbi.nlm.nih.gov/articles/PMC8796717/. Accessed March 10, 2026.
3. Han H, Yi B, Zhong R, et al. From gut microbiota to host appetite. Microbiome. 2021;9(1). https://pmc.ncbi.nlm.nih.gov/articles/PMC8293578/. Accessed March 4, 2026.
4. Sadagopan A, Mahmoud A, Begg M, et al. Understanding the role of the gut microbiome in diabetes and therapeutics targeting leaky gut. Cureus. 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10405753/#:~:text=We%20know%20that%20diet%20can,7%2C11%2C12%5D. Accessed March 4, 2026.
5. Fujisaka S, Watanabe Y, Tobe K. The gut microbiome: a core regulator of metabolism. Journal of Endocrinology. 2023;256(3). https://joe.bioscientifica.com/view/journals/joe/256/3/JOE-22-0111.xml. Accessed March 5, 2026.
6. Canadian Digestive Health Foundation. Gut Health and Prebiotics. 2022. https://cdhf.ca/en/gut-health-and-prebiotics/. Accessed March 3, 2026.
7. University of Calgary. How fit is your gut microbiome? 2023. https://ucalgary.ca/news/how-fit-your-gut-microbiome#:~:text=Jane%20Shearer%2C%20PhD%2C%20a%20professor,exercise%20on%20the%20gut%20microbes. Accessed March 3, 2026.
8. Dietitians of Canada: Unlock food. Are Fermented Foods Good for Me? 2023. https://www.unlockfood.ca/en/Articles/Cooking-And-Food/Vegetables-and-Fruit/Are-Fermented-Foods-Good-For-Me#:~:text=Kombucha%20–%20is%20a%20fermented%20drink,bread%20made%20from%20fermented%20flour. Accessed March 3, 2026.

Shop Essentials for Better Gut Health

Your Health Matters

Enroll in our Weight Management Program

Get a comprehensive assessment and create a personalized weight management plan. Book a free consultation to learn more.

Book Now Learn More