GLP-1 supplements: do berberine, fiber and probiotics work? What the trials found

Do GLP-1 supplements contain GLP-1?

No. GLP-1 is a gut hormone your body releases after you eat. It tells your brain you are full and helps your pancreas release insulin. Your own GLP-1 is broken down fast: the US Victoza label puts its half-life at 1.5 to 2 minutes.¹⁷ Half-life is the time it takes for half of it to clear from the blood.

The medicines, such as semaglutide (Ozempic, Wegovy) and tirzepatide (Zepbound, Mounjaro), are man-made molecules built to resist that breakdown. In the US they are prescription drugs, as is liraglutide (Victoza, Saxenda), so there is no over-the-counter Ozempic.¹⁷ Products sold as "GLP-1 supplements" contain plant extracts, fiber or bacteria that are claimed to nudge your own GLP-1 up. That is a very different thing, as the numbers below show. For the basics, see what GLP-1 is.

Do GLP-1 supplements work? What the trials found

We looked for the strongest human evidence for each common ingredient: meta-analyses of randomized controlled trials (RCTs), which pool many trials where people were assigned by chance to the supplement or a control. Where none existed, we used the best single trial.

Tirzepatide goes further than semaglutide. In SURMOUNT-1, adults with obesity and without diabetes lost 20.9% of their body weight on the highest dose over 72 weeks, vs 3.1% on placebo.¹² The supplement trials were also much shorter, often weeks rather than more than a year, so the comparison is rough. But the gap is more than tenfold. See how much weight people lose on GLP-1 medication.

Is berberine "nature's Ozempic"?

Berberine is a bitter compound from plants such as goldenseal and barberry. The "nature's Ozempic" label comes from social media, not from studies. The largest meta-analysis, published in 2026, pooled 23 randomized trials in adults. Berberine lowered body weight by 0.88 kg, BMI by 0.48 points and waist size slightly, compared with control.¹ An earlier 2020 meta-analysis of 10 studies found no significant change in weight, though BMI and waist size dropped a little.²

The 2026 authors noted that many trials did not report the purity or strength of the berberine used and had problems such as a lack of blinding.¹ We found no trial comparing berberine with a GLP-1 medicine head to head.

Fiber, psyllium and glucomannan

Viscous fiber is the kind that forms a gel in water, like psyllium, glucomannan and guar gum. In 15 trials of 1,347 adults who were also on a calorie-cut diet, adding viscous fiber led to 0.81 kg more weight loss and a 1.39-point drop in body fat percentage; the authors rated the evidence as moderate certainty.³ Psyllium on its own did not significantly lower weight across 22 trials.⁴ Glucomannan lowered weight by 0.79 kg across 14 studies, and it also lowered LDL cholesterol.⁵

Fiber does have real benefits for gut health and cholesterol. It just is not a substitute for a GLP-1 medicine on weight. A 2026 review in Advances in Nutrition says fiber does engage the same gut-brain pathway by stimulating your own GLP-1, but that weight loss with fiber alone is typically more modest than with GLP-1 drugs, and that bloating or gas can be a problem if intake rises too quickly.¹⁴

Akkermansia and "GLP-1 probiotics"

Some probiotic products are marketed around GLP-1 because they contain Akkermansia muciniphila, a gut bacterium linked in studies to leaner body weight. In the first human trial, 32 adults with overweight or obesity and insulin resistance completed three months of placebo or Akkermansia. The pasteurized form improved insulin sensitivity by about 29% vs placebo. Weight fell 2.27 kg more than placebo, but that difference was not statistically significant.⁸ Several authors held patents on Akkermansia.

A company-run trial of a five-strain formula that includes Akkermansia enrolled 76 adults with type 2 diabetes. Over 12 weeks, A1C, a measure of average blood sugar, fell 0.6 points more than with placebo. All authors were employees of the maker.⁹ That trial measured blood sugar, not weight.

For probiotics in general, a 2018 meta-analysis found 0.60 kg more weight loss than placebo over 3 to 12 weeks, which the authors called small.⁶ A 2026 meta-analysis of 10 trials found no significant effect on weight.⁷

Yerba mate and other ingredients

In a 12-week trial in 30 Korean adults with obesity, 3 g a day of yerba mate reduced body fat mass, body fat percentage and waist-to-hip ratio compared with placebo.¹⁰ It was a small single trial. Many "GLP-1" blends also add green tea, chromium, cinnamon or other extracts. We did not find good evidence that any of them comes close to the weight loss seen with the medicines.

Can food raise your own GLP-1?

Yes, a little. In a crossover study, 25 men ate three meals with the same calories on different days. A meal with 50% of calories from protein raised the GLP-1 response 20% more than a normal meal with 14% protein, and people felt fuller and less hungry. But they did not eat less at lunch four hours later.¹³ Fiber raises your own GLP-1 too, mostly through fermentation in the gut.¹⁴

Those are real effects, but they are natural-sized. Your own GLP-1 still lasts minutes, not days. Protein and fiber matter more for people on a GLP-1 for other reasons: eating enough protein helps protect muscle, and fiber helps with constipation. See how much protein you need on a GLP-1 and what to eat on a GLP-1.

What the FDA and FTC say

• Supplements are not approved before sale. The FDA says it has no authority to approve dietary supplements before they are marketed. A product that claims to treat, cure or prevent a disease counts as a drug, and only a drug can legally make that claim.¹⁵
• Unapproved "GLP-1" drops. In a December 10, 2024 warning letter, the FDA told the seller of "Veronvy Metabolic Boost Drops" that its products were unapproved new drugs and misbranded. The website had claimed under a GLP-1 heading that the drops suppress appetite and slow stomach emptying, and had falsely said they were FDA-approved.¹⁵
• "Research use" semaglutide. The FDA says it has warned companies selling GLP-1 products falsely labeled "for research purposes" or "not for human consumption" that were in fact sold for people to inject, with dosing instructions. It also warns about counterfeit products that may contain the wrong ingredients.¹⁵
• Hidden drugs in weight-loss "supplements". The FDA keeps a list of weight-loss products found to contain hidden drug ingredients, some falsely sold as dietary supplements or all-natural, and says the list covers only a small fraction of such products. As of November 2026, none of the notices on that list named semaglutide or tirzepatide.¹⁵
• Deceptive GLP-1 marketing. In July 2025 the Federal Trade Commission (FTC), which polices advertising, charged a GLP-1 telehealth company, NextMed, with fake reviews, before-and-after photos of people who were not customers and unsupported claims that members lose 53 pounds on average. The company agreed to pay $150,000, and the order became final in December 2025.¹⁶