Best Weight Loss Supplements: 8 Formulas Compared on Evidence, Transparency and Safety
In weight loss supplements, what matters most is honest labelling and avoiding harm, because even the better-studied ingredients produce small effects. The formulas that stand out in this comparison are stimulant-free and transparent — LeanBiome discloses its probiotic strains and green tea extract dose, and Ignitra leads with berberine and glucomannan rather than stimulants — while products built on undisclosed caffeine, garcinia or drug-like “GLP-1” naming rank lowest. No product here has shown meaningful weight loss in a published trial of its own formula.
This guide contains no affiliate purchase links. FactoWiki may earn commissions through links on individual product review pages; those relationships did not determine the order or conclusions below. See our affiliate disclosure. General information, not medical advice.
Short verdict
If you want a supplement alongside diet changes, choose stimulant-free and transparent first: LeanBiome, then Ignitra if you are not taking diabetes medication. Skip products with hidden caffeine, garcinia or prescription-drug-style names. If weight is affecting your health, a doctor can discuss treatments with far stronger evidence.
How we selected and assessed the products
FactoWiki has reviewed twelve weight and metabolism products. Eight are compared in detail below; four are summarised later because we could not establish their formulas. Each was assessed on the same criteria, in order of weight:
- Human evidence for the main ingredients, measured as weight or body-fat change, not metabolic-rate or fat-oxidation markers alone.
- Meaningful, disclosed doses.
- Formula transparency, including disclosure of caffeine content.
- Safety and interactions — stimulants, liver-injury signals and medication interactions.
- Category relevance.
- Marketing claims — drug-like naming, rapid-loss testimonials and “fat-burning” promises counted against a product.
- Price, value and refund terms — considered last.
We did not assign scores. Full criteria are in our review methodology.
Quick comparison
| Product | Main ingredients | Dose transparency | Evidence strength | Main advantage | Important limitation | Price / value | Who may consider it |
|---|---|---|---|---|---|---|---|
| LeanBiome | Probiotics (~20B CFU), green tea extract 300 mg, inulin | Good — strains and key amounts listed | Limited–moderate | Most transparent; stimulant-free | Strain match to trials unconfirmed | 180-day refund; price not verified | Stimulant-free, label-conscious buyers |
| Ignitra | Berberine, glucomannan, turmeric | Proprietary blend | Moderate (glucose) | Best-evidenced ingredients | Berberine + diabetes meds | ~$49/bottle; 60-day refund | People not on diabetes medication |
| Java Burn | Green tea, chlorogenic acid, carnitine, chromium | Amounts not established | Weak–limited | Short, avoids risky extras | Relies on coffee caffeine | $49–69/pouch; 60-day refund | Coffee drinkers wanting a minor add-on |
| Metabo Drops | Java Burn-type stack + African mango | Amounts not established | Weak | Liquid format | No edge over Java Burn | $49–69/bottle; 60-day refund | Drop-format preference only |
| NovuBurn | BHB salts, MCT | Amounts not established | Weak for fat loss | Stimulant-free | Ketones ≠ fat loss; salt load | 60-day refund; price not verified | Existing low-carb dieters |
| Mounjaboost | Green tea, turmeric, African mango, maca | Amounts not established | Weak | Few ingredients | Drug-like naming | $49–69/bottle; 60-day refund | Not recommended |
| VittaBurn | Guarana, green tea, raspberry ketones + adaptogens | Undisclosed caffeine | Weak | Mild thermogenics | Hidden stimulant dose | $49–69/bottle; 60-day refund | Caffeine-tolerant buyers only |
| FlashBurn | Green tea, garcinia, guarana, carnitine (varies) | Poor — versions differ | Weak | — | Liver-risk combination | $49–69/bottle; 60/180-day refund | Not recommended |
Prices and refund windows are as described by sellers at the time of our individual reviews and were not re-verified for this guide. Confirm the total delivered cost, subscription terms and written refund conditions at checkout. “Evidence strength” refers to the main ingredients, not the finished product.
Products compared
Products are listed in order of how they performed on the criteria above.
LeanBiome
What it is: A capsule combining a multi-strain probiotic with a caffeine-free green tea extract and prebiotic fibre.
Key ingredients: Nine probiotic strains (around 20 billion CFU) including Lactobacillus gasseri; Greenselect Phytosome green tea extract (300 mg); inulin; Sphaeranthus indicus and Garcinia mangostana extracts.
What is actually different: It is the most transparent formula in this group: strains, CFU count and the green tea extract amount are disclosed, and it avoids stimulants.
Evidence strengths: A randomised trial of one L. gasseri strain reported small reductions in abdominal fat over 12 weeks, and the Sphaeranthus/mangosteen combination has manufacturer-sponsored trials. Weaknesses: Probiotic effects are strain-specific: the best-known L. gasseri trial used strain SBT2055 in fermented milk, and we did not confirm that LeanBiome uses the same strain. Effects reported were small. No product trial.
Dose transparency: Good by category standards — strains, CFU and a key extract amount are listed.
Safety issue to check: Generally well tolerated; temporary bloating is common when starting probiotics or inulin. People who are immunocompromised should ask a doctor before taking probiotics.
Pros
- Most transparent label in this group
- Stimulant-free
- 180-day refund window per seller
Cons
- Strain-level match to published trials not confirmed
- Small expected effect
Who may reasonably consider it: Adults who want a stimulant-free, label-transparent product alongside diet changes and accept that any effect is likely to be small. Read the full LeanBiome review.
Ignitra
What it is: A capsule marketed for metabolism and blood sugar.
Key ingredients: Berberine, konjac glucomannan fibre, turmeric extract, prickly pear, mangosteen and riboflavin.
What is actually different: It leads with two ingredients with genuine human research — berberine for blood sugar and glucomannan for fullness — rather than stimulants.
Evidence strengths: Berberine has consistent blood-sugar and cholesterol research; glucomannan has satiety data and some weight-loss trials. Weaknesses: Weight-loss meta-analyses of glucomannan disagree, and the largest effects are small. Berberine is primarily a glucose ingredient. A proprietary blend hides both doses. No product trial.
Dose transparency: Weak: proprietary blend.
Safety issue to check: Berberine can add to the effect of diabetes medicines (risk of low blood sugar) and alters the metabolism of some other drugs. Glucomannan must be taken with plenty of water and can delay absorption of oral medicines.
Pros
- Best-evidenced ingredients among the capsules
- Stimulant-free
- Around $49 per bottle listed; 60-day refund window per seller
Cons
- Doses hidden
- Significant medication interaction for people with diabetes
Who may reasonably consider it: Adults not taking diabetes medication who are interested in appetite and blood-sugar support, and who check with a pharmacist if they take any regular medicine. Read the full Ignitra review.
Java Burn
What it is: A flavourless powder stirred into coffee.
Key ingredients: Green tea extract, chlorogenic acid, L-carnitine, L-theanine, chromium and vitamins B6, B12 and D3.
What is actually different: A short, stimulant-light ingredient list designed to be combined with the caffeine in the buyer’s own coffee.
Evidence strengths: Green tea catechins and caffeine have small effects on energy expenditure in some studies. Weaknesses: A Cochrane review found green tea preparations produced small, clinically unimportant weight loss. L-carnitine and chromium have weak weight evidence. No product trial.
Dose transparency: Amounts not established in our review.
Safety issue to check: Total caffeine depends on how much coffee you drink; concentrated green tea extract has been linked to rare liver injury.
Pros
- Short, avoids garcinia and stimulant stacks
- $49–69 per pouch listed; 60-day refund window per seller
Cons
- Relies on coffee caffeine
- Weak evidence for most ingredients
Who may reasonably consider it: Regular coffee drinkers without heart-rhythm, blood-pressure or liver concerns who want a minor add-on to diet changes. Read the full Java Burn review.
Metabo Drops
What it is: A liquid version of the coffee-additive formula.
Key ingredients: Green tea extract, chlorogenic acid, L-carnitine, chromium, African mango extract, L-theanine and vitamins B6, B12 and D.
What is actually different: Near-identical to Java Burn with African mango added and a liquid format.
Evidence strengths: Shares Java Burn’s small green tea and caffeine rationale. Weaknesses: African mango evidence is weak and inconsistent, according to the NIH Office of Dietary Supplements. Marketing uses implausible weight-loss testimonials. No product trial.
Dose transparency: Amounts not established.
Safety issue to check: Same caffeine and green tea extract cautions as Java Burn.
Pros
- Liquid format
- 60-day refund window per seller
Cons
- Adds a weak ingredient to a weak stack
- Unrealistic marketing claims
Who may reasonably consider it: No clear advantage over Java Burn; consider only if you specifically prefer drops. Read the full Metabo Drops review.
NovuBurn
What it is: An exogenous ketone capsule marketed for keto dieters.
Key ingredients: Beta-hydroxybutyrate (BHB) salts as calcium, magnesium and sodium BHB; calcium citrate; MCT powder.
What is actually different: It uses ketone salts rather than plant extracts or stimulants.
Evidence strengths: BHB salts briefly raise blood ketone levels; MCTs are converted to ketones. Weaknesses: Raising blood ketones with a supplement is not the same as burning body fat, and evidence that ketone salts cause fat loss is weak. No product trial.
Dose transparency: Amounts not established in our review.
Safety issue to check: Sodium and mineral load matters for people with high blood pressure, heart failure or kidney disease; digestive upset is common.
Pros
- Stimulant-free
- 60-day refund window per seller
Cons
- Weak fat-loss rationale
- Mineral-salt load
Who may reasonably consider it: Only people already following a low-carbohydrate diet who want a short-term energy product and have no blood-pressure or kidney concerns. Read the full NovuBurn review.
Mounjaboost
What it is: A liquid drop marketed as “GLP-1-inspired”.
Key ingredients: Green tea extract, Korean turmeric, African mango seed and maca root.
What is actually different: Its name closely resembles a prescription weight-loss drug, but it is a herbal supplement with no GLP-1 drug in it.
Evidence strengths: Green tea has a small thermogenic effect. Weaknesses: African mango, turmeric and maca have little or no weight-loss evidence. The “GLP-1” framing implies a drug-like effect the formula has not shown. No product trial.
Dose transparency: Amounts not established.
Safety issue to check: Green tea extract liver caution; the naming may lead buyers to believe they are taking a medicine.
Pros
- Few ingredients
- $49–69 per bottle listed; 60-day refund window per seller
Cons
- Misleading drug-like positioning
- Weak ingredient evidence
Who may reasonably consider it: We cannot identify a buyer for whom this is the better choice; anyone interested in GLP-1 medicines should speak to a doctor. Read the full Mounjaboost review.
VittaBurn
What it is: A liquid “fat-burner” drop with a stimulant.
Key ingredients: Green tea, African mango seed, guarana, cayenne, raspberry ketones, ginger, maca, grape seed, eleuthero and astragalus.
What is actually different: Adds guarana caffeine and raspberry ketones to the common green tea base.
Evidence strengths: Green tea, cayenne and caffeine have small thermogenic effects. Weaknesses: Raspberry ketones lack human weight-loss evidence, according to the NIH Office of Dietary Supplements. Adaptogens included have no weight evidence. No product trial.
Dose transparency: Amounts not established; guarana caffeine content undisclosed.
Safety issue to check: Undisclosed caffeine matters for high blood pressure, arrhythmia, anxiety, pregnancy and people already drinking coffee.
Pros
- Mild thermogenic ingredients
- $49–69 per bottle listed; 60-day refund window per seller
Cons
- Hidden caffeine dose
- Raspberry ketones are unsupported
Who may reasonably consider it: Only people who tolerate caffeine well and can confirm the total amount; stimulant-free options above carry less risk. Read the full VittaBurn review.
FlashBurn
What it is: A capsule with a formula that differs between versions.
Key ingredients: Typically green tea extract, garcinia cambogia, cayenne, guarana and L-carnitine, sometimes with African mango, glucomannan and chromium.
What is actually different: It includes garcinia, the ingredient in this category most associated with liver-injury reports.
Evidence strengths: Green tea, cayenne and caffeine have small thermogenic effects; glucomannan has satiety data when present. Weaknesses: Garcinia’s weight-loss evidence is weak, and the NCCIH notes reports of liver injury. Inconsistent formula; no product trial.
Dose transparency: Poor: versions differ and amounts are not disclosed.
Safety issue to check: Garcinia and concentrated green tea extract have both been linked to liver injury; guarana adds undisclosed caffeine.
Pros
- Some thermogenic ingredients
- $49–69 per bottle listed; 60 or 180-day refund window depending on the seller page
Cons
- Liver-risk ingredients combined
- Formula varies
Who may reasonably consider it: We would not choose it over the stimulant-free products above. Avoid if you have liver disease or drink heavily. Read the full FlashBurn review.
Also reviewed, not compared in detail
We could not establish reliable ingredient lists for AlkaTide (a gummy whose supplied image shows only the front label), All Day Slimming Tea (check for laxative herbs such as senna), Hormovance or Trimology.
What ingredients have the best evidence?
These summaries describe research on individual ingredients, prepared by the FactoWiki Research Team. They do not show that any product above works. The NIH Office of Dietary Supplements fact sheet on weight-loss supplements is the most comprehensive independent overview.
Green tea extract Small effect
A Cochrane review of randomised trials lasting at least 12 weeks in overweight or obese adults found green tea preparations produced a very small weight loss that was unlikely to be clinically important (Jurgens et al., 2012). Concentrated extracts have been linked to rare liver injury. See is green tea extract safe.
Glucomannan Mixed
One meta-analysis of randomised trials did not find statistically significant weight loss with glucomannan (Onakpoya et al., 2014); other meta-analyses report small effects. It forms a gel and must be taken with water. See our glucomannan guide.
Berberine Moderate for glucose
Berberine’s better evidence concerns blood sugar and cholesterol rather than weight; see what berberine does. Its medication interactions are the main reason to check with a pharmacist.
Probiotics (Lactobacillus gasseri) Strain-specific, small
In a 12-week randomised trial of 87 Japanese adults, fermented milk containing L. gasseri SBT2055 reduced abdominal visceral fat area by about 5% compared with control (Kadooka et al., 2010). The study was run by the strain’s manufacturer, and results do not automatically apply to other strains.
Garcinia cambogia and raspberry ketones Weak
Garcinia has weak weight-loss evidence and has been associated with liver injury (NCCIH); see does garcinia work. Raspberry ketones lack human weight-loss trials.
What the research does not prove
Ingredient evidence: a specific extract or strain, at a specific dose, often in trials that also involved diet changes.
Dose evidence: whether a benefit appeared at a particular amount. A proprietary blend or undisclosed dose is not covered by that result.
Finished-product evidence: a trial of the commercial formula itself. None of the eight products compared here has one that we could find.
The research does not show that any of these products causes meaningful weight loss, that raising metabolic rate or blood ketones translates into fat loss, or that combining weak ingredients produces a strong effect. It also does not make any supplement equivalent to prescription GLP-1 treatment: in the STEP 1 trial, weekly semaglutide with lifestyle support produced average weight loss of about 15% over 68 weeks (Wilding et al., 2021), an effect no supplement ingredient has come close to.
How to choose a weight loss supplement
Our guide to comparing weight loss supplements and how to read a supplement label go further. On the Supplement Facts panel, check:
- Ingredient amount: each active listed in milligrams, or CFU and strain names for probiotics.
- Standardised extract: green tea extracts should state catechin or EGCG content.
- Serving size: how many capsules, drops or scoops make the listed dose, and cost per day on that basis.
- Proprietary blends: treat hidden doses as unverified.
- Hidden caffeine: guarana, green coffee, yerba maté and kola nut all contain caffeine even when “caffeine” is not listed.
- Interactions: berberine, glucomannan and green tea extract can affect medicines.
- Third-party verification: genuine USP or NSF certification can be checked on the certifier’s own website. We did not find it for the products compared here.
Our weight loss supplement red flags answer is worth reading before checkout.
Safety
- Liver: concentrated green tea extract and garcinia have been linked to rare but serious liver injury. Stop and seek care for jaundice, dark urine or abdominal pain.
- Stimulants: undisclosed caffeine from guarana or similar herbs can raise heart rate and blood pressure and disturb sleep, especially combined with coffee.
- Blood sugar: berberine can add to diabetes medicines and cause low blood sugar.
- Fibre: glucomannan needs plenty of water and can delay absorption of oral medicines taken at the same time.
- Salts: BHB ketone salts add sodium and other minerals.
- Hidden drugs: the FDA has found some products sold as weight-loss supplements to contain undeclared prescription drugs; products promising rapid results carry the highest risk.
Talk to a doctor before using weight supplements if you are pregnant or breastfeeding, have heart, liver or kidney disease, have diabetes, take regular medication, or have a history of disordered eating. Do not stop or replace prescribed treatment with a supplement.
Frequently asked questions
Which weight loss supplement in this comparison is the best choice?
On transparency and safety, LeanBiome, because it discloses strains and a key extract dose and contains no stimulants. Ignitra has the best-evidenced ingredients but hides doses and interacts with diabetes medicines. None has been shown to cause meaningful weight loss as a finished product.
How much weight can a supplement realistically help you lose?
According to the NIH Office of Dietary Supplements, there is little evidence that weight-loss supplements work, and trial results for the better-studied ingredients generally amount to small differences from placebo. Diet, activity and, where appropriate, medical treatment are far more effective.
Are “GLP-1” supplements the same as Ozempic or Mounjaro?
No. Prescription GLP-1 medicines are drugs tested in large trials — semaglutide produced average weight loss of about 15% over 68 weeks in one major trial. Supplements using GLP-1 language contain herbs or fibres, not these drugs, and have not shown comparable results.
Are stimulant-free fat burners safer?
Generally they avoid caffeine-related risks such as palpitations, raised blood pressure and poor sleep. “Stimulant-free” does not guarantee safety: berberine has drug interactions, and concentrated green tea extract and garcinia have been linked to liver injury.
Can probiotics help with weight loss?
Some specific strains have shown small effects on body fat in trials, but results are strain-specific and modest. A product containing the same species is not necessarily the same strain as the one studied.
How long should I try a weight supplement before deciding?
Most trials ran 8 to 12 weeks. Track weight and waist circumference weekly under a stable diet, and stop if there is no change or you develop side effects.
When should I talk to a doctor about weight instead of buying a supplement?
If you have diabetes, heart, liver or kidney disease, take regular medication, are pregnant or breastfeeding, or have unexplained weight change. A clinician can also discuss whether prescription treatment is appropriate.
Related on FactoWiki
Weight & Metabolism category guide · FlashBurn vs Ignitra · Do weight loss supplements work? · Stimulant-free weight loss supplements · How we review