Cinnamon Supplements and Weight: What Trials and Meta-Analyses Show

Cinnamon supplements appear to lower body weight by roughly 1 kg or less on average, a difference most people would not notice on a scale. The largest weight-focused meta-analysis, covering 21 randomized trials and 1,480 participants, found a pooled change of −0.92 kg (95% CI −1.51 to −0.33), and the trials disagreed with one another far more than chance would explain (I² = 84.2%)^[1]. The signal weakens further in people with type 2 diabetes, and a recent triple-blind trial did not reach significance^[4][8].

What the meta-analyses found

Three reviews carry most of the positive claim. Yazdanpanah 2020 reported reductions in weight and BMI (−0.40 kg/m²; 95% CI −0.57 to −0.22), while waist circumference and body fat fell short of significance^[1]. Mousavi 2020, working from a smaller pool of 12 trials and 786 people, reported −1.02 kg (95% CI −1.66 to −0.38) and said cinnamon “could be recommended” for weight reduction^[2]. Keramati 2022 then pooled 7 meta-analyses in an umbrella review and got −0.67 kg (95% CI −0.99 to −0.35), with no significant change in waist circumference^[3].

Those three results are not three independent confirmations. Reviews of the same small literature tend to share trials, and an umbrella review pools the reviews themselves, so agreement among them says less than it seems to. The recommendation also outruns the size of the effect. For scale, semaglutide 2.4 mg produced a mean change of −14.9% at 68 weeks against −2.4% on placebo in STEP 1^[23]. That comparison crosses trials and populations, so treat it as an order of magnitude, nothing finer. On a 100 kg starting weight, the cinnamon estimate is under 1% of body weight.

Type 2 diabetes: mostly no weight effect

Cinnamon has been studied most in diabetes, and the weight data there are thinner. Jamali 2020 pooled 9 articles and found no significant effect on weight (SMD −0.309; 95% CI −0.793 to 0.175) or BMI^[4]. Namazi 2019, with 18 studies, found no significant BMI change (−0.05 kg/m²; 95% CI −0.52 to 0.42)^[5]. A later review of 28 trials and 3,054 patients found a BMI reduction only in the subgroup taking 2 g/day or less (−1.18 kg/m²; 95% CI −1.97 to −0.39)^[6]. A subgroup finding like that generates a question, and it does not settle one.

PCOS: a small effect with consistent results

The tidiest number comes from polycystic ovary syndrome. A 12-trial review reported −0.47 kg (95% CI −0.80 to −0.15) with an I² of 0%^[7]. The estimate is consistent and also very small. One double-blind PCOS trial, using 1.5 g/day for 12 weeks, found lower fasting insulin, HOMA-IR and LDL, but its other outcome measures, anthropometrics included, did not differ significantly from placebo^[10].

What individual trials show

The trial results below split in ways the pooled figures hide. The Lira Neto trial^[8] was triple-blind and used Ceylon cinnamon, the Gupta Jain trial^[9] produced the largest effect and was registered only after recruitment, and the PCOS trial^[10] found metabolic changes without an anthropometric difference. The two exercise trials^[11][12] are the most instructive: when exercise was the shared background, cinnamon added little that was clearly attributable to it.

Two details deserve a second look. The Lira Neto abstract describes within-group paired comparisons, so its −0.8 kg cannot be read as a clean drug-versus-placebo difference^[8]. The cadet trial concludes that combining Tabata with cinnamon had an advantage, yet its own abstract reports the lowest body fat percentage in the Tabata-only group^[12]. Neither trial settles the question for adults with obesity using a supplement alone.

Dose: the signal points in different directions

Supplement labels often present dosing as settled. The reviews do not agree. Keramati 2022 reported better results at 3 g/day or more^[3]. Mousavi 2020 tied fat-mass reduction to 2 g/day or more for at least 12 weeks^[2]. In type 2 diabetes, the BMI reduction appeared at 2 g/day or less^[6]. Subgroup analyses from a heterogeneous literature can easily produce contradictions like these, and the National Center for Complementary and Integrative Health notes that many cinnamon studies are hard to interpret because the species or plant part tested is often unclear^[17]. Its summary is that it remains unclear whether cinnamon supplements help with diabetes or weight loss.

Is cinnamon a natural GLP-1?

The evidence behind that idea is a crossover meal study in 15 healthy people. Adding 3 g of cinnamon to rice pudding raised the GLP-1 response (ΔAUC p = 0.0082), but satiety, gastric emptying and blood glucose did not significantly change^[13]. A rise in a hormone after a single meal, with no change in how full people felt, is a long way from what a GLP-1 drug does. An earlier study of 14 people found that 6 g delayed gastric emptying slightly (median 34.5% versus 37%) and also left satiety unchanged^[14]. In nine healthy adults, 3 g with a high-fat meal did not alter gastric emptying or appetite^[15].

A systematic review of six trials (363 participants) found inconsistent GLP-1 results and an increase in ghrelin, the hunger-signaling hormone, in the two studies it identified on that hormone^[16]. That is not the profile an appetite suppressant would be expected to show. The same “natural Ozempic” pitch attaches to many supplements, and berberine gets a similar treatment in marketing. We could not find a randomized trial testing cinnamon added to semaglutide or tirzepatide, so any claim of added benefit on those drugs is untested.

Blood sugar may be the better-supported effect

Cinnamon’s stronger data are glycemic. Pooled across 28 trials in type 2 diabetes, fasting glucose fell by 15.26 mg/dL (95% CI −22.23 to −8.30), though with an I² of 88%^[6]. A 2025 umbrella review of 21 meta-analyses highlighted fasting glucose and lipids, with effects more pronounced in diabetes and metabolic syndrome; its abstract reports no body-weight finding^[24]. That difference matters when a product is sold for fat loss on the strength of blood-sugar studies. People asking about the cinnamon water version should note that capsules showed the clearest results in that review^[6], and these pooled figures do not tell you what a brewed drink delivers.

Safety: species decides the coumarin exposure

Cinnamon in food amounts is likely safe, according to NCCIH, which also says larger or prolonged use is sometimes linked to gastrointestinal problems or allergic reactions^[17]. The bigger question for capsule users is coumarin, a compound found in cassia. European risk assessors set a tolerable daily intake of 0.1 mg per kg of body weight, and human data suggest a subgroup is unusually susceptible to its liver effects^[18]. One analysis measured 2.23 mg/g in cassia and under 0.01 mg/g in Ceylon^[19]. Applying those figures, 3 g/day of cassia would deliver about 6.7 mg, close to the 7 mg limit for a 70 kg adult, while the same dose of Ceylon would deliver under 0.03 mg. That is our arithmetic from one measurement, and real products vary.

The product on the shelf is a separate problem. In a 2025 study of 104 cinnamon samples bought from EU retailers, 66.3% failed quality criteria, breached food safety law, looked suspicious for fraud or could be toxic for children because of high coumarin^[20]. Those were cinnamon products sampled in Europe, so the rate does not transfer directly to US capsules. Ceylon labels themselves can be vague about species and chemical profile^[19].

Case reports of liver injury exist, and they cannot establish how often it happens or prove cause on their own. A 73-year-old on a long-term statin developed hepatitis about a week after starting cinnamon supplements, and her doctors attributed it to the combination^[21]. A 34-year-old woman developed acute liver injury after prolonged cinnamon use for weight loss, which resolved after stopping^[22].

How to read the evidence

The pooled estimates suggest that cinnamon may nudge weight down slightly over weeks to months, with wide disagreement among studies and a weaker result in the diabetes trials^[1][4]. If someone chooses to try it anyway, the evidence gives little basis for picking a dose, and the species on the label affects coumarin exposure far more than it affects any demonstrated weight outcome^[19]. Readers comparing options can see how cinnamon sits beside other products in our supplement evidence grades.