Is berberine really “nature’s metformin and Ozempic”? What research actually shows

Claim 1: “Berberine gets similar results to metformin. […] It addresses insulin resistance and can help you lower blood sugar, and insulin resistance and blood sugar are behind people gaining weight.”

What is berberine and why is it compared to metformin?

Berberine is a plant alkaloid that has been used in traditional Chinese medicine for centuries, historically to treat diarrhoea (source). In China, it's still sold as an over-the-counter treatment for gastrointestinal infections. In the United States, it's marketed as a dietary supplement for its blood sugar- and cholesterol-lowering effects (source).

Meanwhile, metformin is one of the most widely prescribed antidiabetic drugs in the world (source). Like berberine, it also has herbal origins, as it was originally derived from French lilac and used to treat symptoms of diabetes in medieval Europe before being approved as a pharmaceutical in the 1950s (source).

The comparison isn't a total stretch: both compounds appear to activate AMPK, an enzyme often described as the body's cellular "energy switch." When AMPK is activated, muscles take up more glucose, fat tissue burns more fatty acids, and the liver produces less glucose – a combination that can improve insulin sensitivity (source; source). Metformin and berberine may also affect the gut. Both can change the gut microbiome, which may contribute to their effects on metabolism (source; source). Berberine is poorly absorbed, so the gut may be an especially important site of its action (source).

Does berberine actually lower blood sugar like metformin?

A 2024 umbrella meta-analysis, which pooled results across eleven prior meta-analyses of randomised controlled trials published between 2012 and 2022, concluded that berberine supplementation could be effective in improving glycaemic control, including improvements in fasting glucose, HbA1c, fasting insulin, and insulin resistance (measured by HOMA-IR). 

There's also an important caveat: this research was conducted in people who already have a metabolic disorder, such as type 2 diabetes, obesity, or polycystic ovary syndrome, and not in metabolically healthy adults. People with existing blood sugar or cholesterol problems may have more room to improve, so these results shouldn't be assumed to carry over to someone with normal metabolic health.

More importantly, improvements in biomarkers do not necessarily reflect improvements in clinical outcomes. HbA1c is currently the gold standard for monitoring long-term glycaemic control, reflecting the average blood glucose over the past 2-3 months (source). However, HbA1c is only a surrogate marker, meaning that it is a quick, measurable laboratory shortcut used to predict a long-term health outcome, but it doesn’t measure health directly (source). This means an improvement in HbA1c after taking berberine doesn’t prove that berberine improves long-term diabetes complications, safety, or overall outcomes, and these findings should therefore be interpreted with caution. They do not mean that berberine is a substitute for metformin or other prescribed medication. 

How does berberine stack up directly against metformin?

A 2021 meta-analysis found that berberine alone was not superior to metformin for lowering blood sugar, and that the reported rates of adverse events between the two were not significantly different. Where the evidence gets more interesting is in combination therapy: that same meta-analysis found that adding berberine to metformin improved fasting glucose, post-meal glucose, HbA1c, and insulin resistance more than metformin alone. A broader 2024 meta-analysis reached a similar conclusion, describing a "synergistic effect" for the berberine-plus-metformin combination. One proposed mechanism is that berberine alters gut bacteria in ways that affect how the body processes metformin, though this remains a hypothesis rather than confirmed via human data (source).

Does insulin resistance even cause weight gain?

Insulin resistance may play a role in weight regulation, but the direction of the relationship is not clear. Insulin is a hormone that regulates how the body uses and stores energy. After a meal, it promotes glucose uptake and storage while suppressing the breakdown of stored fat. When tissues become less responsive to insulin, referred to as insulin resistance, the pancreas can compensate by producing more insulin (source).

Because insulin promotes energy storage and suppresses the breakdown of stored fat, it has been proposed that elevated insulin levels associated with insulin resistance could contribute to weight gain (source). Supporting this theory, a 2020 meta-analysis of seven randomized controlled trials found that interventions that suppressed insulin secretion resulted in modest reductions in body weight and fat mass.

However, the relationship between insulin resistance and body fat may also work in the opposite direction: excess adipose tissue can contribute to insulin resistance. A 2024 longitudinal study followed participants for four years and found that those who subsequently gained 5 kg or more did not initially differ in insulin levels or insulin resistance from participants whose weight remained stable. Insulin resistance increased only after the weight gain occurred. Increased food intake and a genetic factor related to fat metabolism were instead associated with subsequent weight gain. This suggests that insulin resistance may, in some cases, be a downstream consequence of weight gain rather than its primary cause.

Together, these findings suggest that insulin resistance and body weight may influence each other, rather than there being a simple one-way relationship in which insulin resistance causes weight gain.

So, does berberine help with weight loss?

Based on the research so far, the results appear to be inconsistent, and when weight changes are observed, they seem modest. A 2020 meta-analysis including ten randomised controlled trials (RCTs) found moderate improvements in BMI and waist circumference, and no change in body weight. They reported that longer treatment duration was associated with larger reductions in BMI and waist circumference. Another meta-analysis from 2025 included 23 RCTs, and also found moderate improvements in BMI and waist circumference, and an average reduction in body weight of -0.88 kg.

The most recent double-blind RCT is from 2026, and included 337 participants with obesity taking either 1 gram of berberine per day for 6 months or a placebo. The results did not show any differences in body weight, BMI, waist circumference or visceral fat between the group taking berberine and the group taking a placebo.

Is berberine a natural alternative to Ozempic?

Berberine and semaglutide, the active ingredient in weight-loss medications such as Ozempic and Wegovy, work through very different mechanisms – and much of berberine’s proposed mechanism has not been fully established in humans (source). 

As discussed earlier, berberine is thought to act on several metabolic pathways, including AMPK signalling and its effects on the gut (source). Its evidence for weight loss is inconsistent, where one meta-analysis from 2020 found no meaningful change in body weight, while another larger and more recent meta-analysis from 2025 reported a small average weight reduction of 0.88kg. 

On the other hand, semaglutide works as a GLP-1 receptor agonist. It mimics the gut hormone GLP-1, reducing appetite and food intake and helping regulate blood sugar (source). Studies consistently report significant reductions in body weight. A 2024 meta-analysis of randomised controlled trials reported average weight reductions of around 12kg in adults with overweight or obesity. That said, results likely vary by treatment dosage and duration, and diabetes status. 

While berberine and semaglutide may influence some of the same biological processes, there are no published human head-to-head trials comparing the two compounds – direct comparisons appear to be limited to preclinical research. Research on berberine's role in weight loss is also inconsistent and limited overall, and much of its proposed mechanism has not been fully established in humans. For these reasons, berberine cannot be considered a natural alternative to semaglutide. 

Claim 2: “It has very minimal side effects, if any, if you’re taking it in a normal amount, like maybe 1 gram per day or 1.5 grams per day.”

Is berberine safe?

In short term trials berberine is generally well tolerated. A 2023 meta-analysis included 17 RCTs of which most had a duration of 12 weeks, with some extending to 16-24 weeks. It found that overall side effects were similar between berberine and placebo, with gastrointestinal symptoms, such as diarrhea, constipation, nausea, and abdominal discomfort being the most common. Side effects were shown to alleviate or disappear when the dose was lowered or the intervention time was prolonged. A recent trial, lasting 6 months, also found no significant difference in side effects between berberine and placebo. However, these durations are still relatively short, so we still don't know enough about the safety of taking berberine for years.

Nevertheless, the claim that it has “very minimal side effects” is too broad. In animal studies, high doses of berberine have been linked to possible effects on the liver, kidneys, nervous system, and reproductive system (source). These are high-dose animal findings, not evidence of harm at normal human doses, but they are a reminder that berberine shouldn’t be assumed to be completely harmless. Additionally, berberine could interact with some medications by affecting how the body processes drugs (source). 

This ties into a bigger pattern: people often assume "natural" automatically means safer or better than medicine. This is called the appeal to nature fallacy, and it doesn't hold up here. Berberine hasn't been tested nearly as much as metformin or Ozempic, and we still don't fully understand its long-term safety or how it interacts with other drugs. So calling it "nature's Ozempic" or "nature's metformin" is misleading. Decisions about starting, stopping, or combining treatments should be made with a health professional, not based on a supplement's marketing. 

Final take-away

Berberine may have some benefits for metabolic health, but the evidence is far less impressive than the claims surrounding it. It modestly improves blood sugar and insulin-resistance markers, mainly in people who already have metabolic problems, but it is not superior to metformin and no human trials have directly compared it with semaglutide. Its effect on body weight is small and inconsistent, and a recent six-month placebo-controlled recent trial found no meaningful difference from placebo. It appears generally safe in the short term, but its long-term safety and interactions with other medications are still not well understood. 

Claims like "nature's metformin” and “nature’s Ozempic” make comparisons the evidence doesn't support: berberine and Ozempic have never been directly compared, berberine does not outperform metformin, and it has not been established as an effective replacement for metformin. These claims tend to highlight only the positives, without mentioning the potential health harms, such as unclear long-term safety or possible interactions with other medications. This one-sided framing feeds the impression that natural is always better and safer, which is not the case. Anyone considering berberine, especially alongside prescription medication, should discuss it with a qualified healthcare professional rather than basing that decision on a social media claim. 

‍

We have contacted Eric Berg and are awaiting a response.

Disclaimer

This fact-check is intended to provide information based on available scientific evidence. It should not be considered as medical advice. For personalised health guidance, consult with a qualified healthcare professional.