GLP-1 Agonists, Ozempic, and the Gut Microbiome: A Nutritional Therapist’s Take

GLP-1 agonists, namely Ozempic and Wegovy, are medications that have generated tremendous interest for their ability to support weight loss and manage blood sugar levels. Today I thought I’d write about it’s efficacy and research and as always, the lens I use to evaluate their effectiveness starts in the gut. Over the years, I have closely followed the research on bariatric surgery and how individuals who have opted for this, resulted in nutritional deficiencies. GLP-1 class of drugs have made weight loss easier and have taken the world by storm, although we are lacking data post two years of using this medication. 

Over the past few years, I’ve been watching the research closely and observing first hand how these medications affect my clients, especially their gut microbiome. While the world talks about appetite suppression, muscle atrophy and weight loss, I’m looking deeper into the ripple effects in the gastrointestinal tract and it’s effects on bone health.

Because here’s the thing: everything we eat first interacts with the gut microbiome before it impacts the rest of the body. And when someone is struggling with obesity or persistent weight gain, I always go back and ask what’s happening in their gut? How does the body get to the point, where someone becomes weight loss resistant. 

In most Western nations, gut health is on the decline. One of the most compelling reasons is a diet dominated by processed foods. Over 40% of the average adult’s diet now comes from processed foods and for children, that number jumps to around 60%. That’s more than half of a child’s daily intake coming from packaged, refined, shelf-stable ingredients often stripped of fiber, color, and nutritional value. Imagine the burden this places on a developing gut and a still-maturing liver. The gut microbiome simply cannot thrive on a diet of emulsifiers, synthetic additives, and ultra-processed oils. Over time, this leads to a damaged gut lining, reduced microbial diversity, and a chronic inflammatory state. And perhaps most concerningly, it contributes to a depletion of natural GLP-1 production the very hormone these medications are now trying to replicate. So it’s not just about hunger or weight. It’s about what happens when the microbiome is starved of diversity, fiber, and the raw materials it needs to do its job.

GLP-1 agonists like semaglutide (the active ingredient in Ozempic) work by mimicking our body’s own incretin hormones, compounds naturally released from the gut to modulate blood sugar and appetite. Wegovy takes it one step further, functioning as both a GLP-1 and GIP agonist. GLP-1 (Glucagon-Like Peptide-1) slows gastric emptying, promotes satiety, and lowers blood glucose. GIP (Gastric Inhibitory Polypeptide) supports insulin sensitivity and may reduce fat accumulation.

But these medications are no longer just for diabetes. Researchers are now exploring their use in Alzheimer’s disease, addiction recovery, and even psychiatric disorders, due to their ability to modulate neuroinflammation. This class of drugs has truly changed the game but even more importantly, it has given the world an insight into what better management of blood sugars can do.

The SUSTAIN-1 Trial: Where It All Began

The journey to today’s GLP-1 buzz began with a landmark trial, SUSTAIN-1 conducted across eight countries including the U.S., Japan, and the U.K. It was a double-blind, placebo-controlled study involving individuals newly diagnosed with type 2 diabetes. Participants managed their blood sugar through diet and exercise and self-administered weekly injections of semaglutide or a placebo over 30 weeks. The results were significant: improved HbA1c levels, noticeable weight loss, and a manageable safety profile. This data led to Ozempic’s FDA approval in 2017 and paved the way for widespread interest in GLP-1-based therapies for both diabetes and obesity. Post this study, we have had numerous other studies, suggesting its efficacy and ability to cause rapid weight gain and lowering of glucose related biomarkers. 

On the flip side, what this trial saw was a massive reduction of muscle mass and about half of the participants who were on the drug, re-gained the weight back within the next consecutive two years. What this drug did fail in, what to teach the participants behaviour change. 

Here’s the good news: we can support natural GLP-1 production by feeding the gut what it actually needs. Certain bacterial strains in the gut like Akkermansia muciniphila are known to play a role in metabolic regulation and may even influence GLP-1 levels. This bacteria responds to dietary diversity, color, polyphenols, and consistent physical activity especially heavy resistance training.

Other species like Roseburia and Faecalibacterium prausnitzii are butyrate-producing bacteria, critical for gut lining integrity, inflammation reduction, and brain health. They thrive on fiber-rich, whole foods, not lab-made shakes or nutrient-devoid packaged snacks. So yes, you can influence GLP-1 through food, movement, and lifestyle—especially if you’re also using medication.

Here’s the uncomfortable truth: many people regain the weight after stopping these medications. Studies confirm it.  The medication does the work, but it doesn’t teach you how to eat, move, or think about health differently. You can lose weight on Ozempic while still drinking your calories, skipping workouts, and relying on processed foods. That’s the trap. Without building foundational habits, you’re left with an empty framework.

I’m not against these medications. In fact, I find their potential fascinating. But I see them as tools not cures. If you’re on Ozempic or Wegovy, or thinking about it, I urge you to think about your gut health, nutrient intake, fiber diversity, and physical activity. That’s what will sustain your results and protect your long-term well-being.