Obesity

Multiple independent meta-analyses of RCTs report that Nigella sativa supplementation lowers body weight (about −2.1 kg), BMI and waist circumference, with a 2025 GRADE review adding body-fat percentage and waist-to-hip ratio to the improved measures ^{32,33,34Reference 32Namazi N et al. · 2018Meta-analysisThe effects of Nigella sativa L. on obesity — systematic review and meta-analysisView study →Reference 33Mousavi SM et al. · 2018Meta-analysisEffect of Nigella sativa supplementation on obesity indices — systematic review and meta-analysis of randomized controlled trialsView study →Reference 34Jafari A et al. · 2025Meta-analysisDoes Nigella sativa supplementation improve cardiovascular disease risk factors? A GRADE-assessed systematic review and dose-response meta-analysis of 82 randomized controlled trialsView study →}.

The changes are consistent in direction but small, mostly in overweight or metabolically-unwell populations from short trials — and the fixed oil often outperforms ground seed, so a random spoonful of seeds does not equal the trial preparation.

Caffeine acutely stimulates thermogenesis and lipolysis and increases satiety, effects amplified by chlorogenic acid, and green-coffee-extract trials show small weight reductions ^{12,13Reference 12Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →Reference 13Onakpoya et al. · 2011Meta-analysisThe use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trialsView study →}. Systematic reviews judge those trials small, short, methodologically weak and often industry-linked, so the effect is real but minor and of uncertain durability — and tolerance to the thermogenic response develops with habitual intake.

Two 12-week randomized, placebo-controlled trials used the marketed preparation (ForsLean, ~10% forskolin, 250 mg twice daily): in overweight/obese men it significantly reduced body-fat percentage and fat mass by DXA and raised free testosterone ^{14Reference 14Godard MP et al. · 2005RCTBody composition and hormonal adaptations associated with forskolin consumption in overweight and obese men — [randomised, placebo-controlled trial]View study →}, but a parallel trial in women found no significant fat loss, only a blunting of weight gain ^{15Reference 15Henderson S et al. · 2005RCTEffects of Coleus forskohlii supplementation on body composition and hematological profiles in mildly overweight women — [randomised, placebo-controlled trial]View study →}. The cAMP→hormone-sensitive-lipase mechanism is plausible, but the human result is small, sex-divergent and not consistently a fat-loss outcome.

Fenugreek’s viscous soluble fiber (galactomannan) drives an appetite effect: 8 g of isolated fenugreek fiber at a meal significantly increased satiety and fullness and reduced hunger and subsequent food intake in obese subjects, though palatability fell ^{16Reference 16Mathern et al. · 2009RCTEffect of fenugreek fiber on satiety, blood glucose and insulin response and energy intake in obese subjects — randomized crossover trialView study →}, and lipid/anthropometric meta-analyses report small reductions in body weight or waist circumference in some pooled analyses ^{17Reference 17Askarpour et al. · 2020Meta-analysisEffect of fenugreek supplementation on blood lipids and body weight: A systematic review and meta-analysis of randomized controlled trialsView study →}. The satiety signal comes largely from single-meal isolated-fiber studies and sustained weight-loss evidence is weak and confounded.

The satiety signal is Griffonia’s most internally-consistent human data: in a double-blind RCT, obese adults given 5-HTP 900 mg/day lost significant weight, cut carbohydrate intake and reported early satiety with and without a diet ^{21Reference 21Cangiano C et al. · 1992RCTEating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan — randomised controlled trialView study →}, and a separate RCT in overweight women used a sublingual spray naturally containing 5-HTP and reported increased satiety with confirmed bioavailability ^{22Reference 22Rondanelli M et al. · 2009RCTSatiety and amino-acid profile in overweight women after a natural plant-extract (5-hydroxytryptophan) sublingual spray — randomised, double-blind, placebo-controlled trialView study →}.

Samples are small, long-term data absent, and nearly all evidence is for isolated 5-HTP rather than whole seed. It applies to Griffonia only as far as a given extract delivers a clean 5-HTP dose.

A 12-week RCT in metabolic-syndrome patients (600 mg/day standardized leaf extract) produced significant reductions in body weight and BMI, and a comparative RCT in obese adults found favorable effects on adipokines (though berberine outperformed it on body composition), with reviews citing gymnemic acid’s glucose-absorption and reversible sweet-taste-blocking actions ^{26,27,28Reference 26Zuñiga et al. · 2017RCTEffect of Gymnema sylvestre administration on metabolic syndrome, insulin sensitivity, and insulin secretion — randomised, double-blind, placebo-controlled trialView study →Reference 27Bandala et al. · 2024RCTComparative effects of Gymnema sylvestre and berberine on adipokines, body composition, and metabolic parameters in obesity — randomised controlled trialView study →Reference 28Pothuraju et al. · 2014Systematic reviewA systematic review of Gymnema sylvestre in obesity and diabetes managementView study →}.

Effects are real but modest, from small (n≈24–50), short trials with no long-term maintenance data, and it is unproven that sweet-taste suppression translates into sustained lower intake.

A 16-week double-blind RCT in 117 overweight adults found a standardized Gynostemma extract (ActivAMP) significantly reduced total body weight, BMI, total fat mass and gynoid fat versus placebo — men losing visceral fat specifically — consistent with high-fat-diet mouse data and an AMPK-activation mechanism confirmed in human muscle ^{29,30,31Reference 29Rao et al. · 2022RCTThe effect of an orally-dosed Gynostemma pentaphyllum extract (ActivAMP) on body composition — double-blind randomised placebo-controlled trialView study →Reference 30Li et al. · 2023Meta-analysisThe role of Gynostemma pentaphyllum in regulating hyperlipidemia — meta-analysisView study →Reference 31Nayyar et al. · 2023RCTGynostemma pentaphyllum increases exercise performance and alters mitochondrial respiration and AMPK in healthy males — randomised controlled trialView study →}.

The evidence rests on a single body-composition RCT of one proprietary extract, and ‘gypenoside’ is a shifting 200-plus-saponin family, so a cup of jiaogulan tea is not the tested product.

A meta-analysis of 6 RCTs (354 overweight/obese participants, mean 10.8 g/day over ~4.8 months) found body weight −2.1 kg, BMI −0.8 kg/m² and waist circumference −2.2 cm versus control ^{37Reference 37Gibb et al. · 2023Meta-analysisPsyllium is a natural nonfermented gel-forming fiber that is effective for weight loss: a comprehensive review and meta-analysis — meta-analysisView study →}, with a crossover satiety RCT confirming that 6.8–10.2 g before meals reduced inter-meal hunger and desire to eat ^{38Reference 38Brum et al. · 2016RCTSatiety effects of psyllium in healthy volunteers — randomised controlled trialView study →}. The evidence base is small (6 trials), the effect modest, and pre-meal timing appears essential. Psyllium supports dietary change rather than acting as a weight-loss agent.

Green-tea catechins with caffeine modestly increase energy expenditure and fat oxidation; a meta-analysis found roughly 1.3 kg of weight loss and improved maintenance, but the effect was blunted by high habitual caffeine intake ^{39Reference 39Hursel et al. · 2009Meta-analysisThe effects of green tea on weight loss and weight maintenance: a meta-analysisView study →}, while the more conservative Cochrane review of ≥12-week RCTs concluded green tea produces only small, non-significant weight loss of little clinical importance ^{40Reference 40Jurgens et al. · 2012Systematic reviewGreen tea for weight loss and weight maintenance in overweight or obese adults — systematic review (Cochrane)View study →}.

Caffeine appears necessary for much of the thermogenic effect, so the benefit is marginal and largely absent in caffeine-habituated people.

A 12-week randomized, placebo-controlled trial in obese Korean adults found maté capsules significantly reduced body-fat mass, percent body fat and waist-hip ratio, and acute crossover RCTs showed 1–2 g raised fat oxidation and energy expenditure during exercise ^{41,42,43Reference 41Kim et al. · 2015RCTAnti-obesity effects of Yerba Maté (Ilex paraguariensis): a randomized, double-blind, placebo-controlled clinical trialView study →Reference 42Alkhatib · 2014RCTYerba Maté (Ilex paraguariensis) ingestion augments fat oxidation and energy expenditure during exercise — randomised crossover trialView study →Reference 43Alkhatib et al. · 2017RCTYerba Maté (Ilex paraguariensis) metabolic, satiety, and mood state effects at rest and during prolonged exercise — randomized trialView study →}.

Against this, a 2025 meta-analysis of 13 RCTs found no significant effect on BMI or waist circumference and a 2026 crossover trial was null for energy expenditure ^{44Reference 44Li et al. · 2025Meta-analysisYerba Maté and its impact on glycemic control and metabolic health: a systematic review and meta-analysis of RCTsView study →}. The one positive body-composition result used a concentrated capsule extract, not tea, and acute fat-oxidation gains do not clearly translate to sustained loss.

Yerba santa has one human trial, and it is for weight. A 12-week randomized, placebo-controlled trial of a proprietary ‘Santa herba’ (E. californicum) extract in 49 overweight and obese women reported significantly reduced body weight and body fat versus placebo, with a trend toward lower leptin, and supporting lab work showed adenosine A2A-receptor binding suggesting an energy-metabolism effect ^{45Reference 45Mödinger Y et al. · 2021RCTA Food Supplement with Antioxidative Santa Herba Extract Modulates Energy Metabolism and Contributes to Weight Management — randomised placebo-controlled clinical trialView study →}.

The extract is undisclosed and proprietary, and its dose does not convert to any leaf dose.

In rodent and cell models the alkaloid piperine reduces diet-induced weight gain by inhibiting intestinal fatty-acid absorption (down-regulating FABP2 and CD36) and by repairing the gut barrier to lower metabolic endotoxemia, with high-fat-diet rats showing less hepatic fat and better insulin sensitivity ^{1,2Reference 1Wang et al. · 2021Piperine improves obesity by inhibiting fatty-acid absorption and repairing intestinal barrier function — animal / cellView study →Reference 2Wang et al. · 2022AnimalPiperine attenuates hepatic steatosis and insulin resistance in high-fat-diet-induced obesity — ratView study →}. No human trial has tested piperine or black pepper alone for weight or body-composition endpoints, and the rat doses do not translate to culinary or supplement intake.

In high-fat/high-sucrose-fed mice a crude camu-camu extract prevented weight and fat-mass gain, raised energy expenditure via brown-adipose UCP1 (linked to bile-acid TGR5 signaling and an Akkermansia-enriched microbiota), and germ-free mice colonized with microbiota from treated donors gained less weight, establishing causality ^{3,4Reference 3Anhê FF et al. · 2019AnimalTreatment with camu camu (Myrciaria dubia) prevents obesity by altering the gut microbiota and increasing energy expenditure in diet-induced obese miceView study →Reference 4Abot A et al. · 2022AnimalCamu-Camu reduces obesity and improves diabetic profiles of obese and diabetic mice: a dose-ranging studyView study →}.

There is no dedicated human weight-loss trial (human data concern liver fat), and effective mouse doses do not translate simply to human intake.

Cha de bugre is a traditional Brazilian slimming/appetite-suppressant tea, but the pharmacology is thin and mixed: a dry extract prevented weight gain and reduced food intake in diet-induced obese rats and anorectic effects appeared in mice at 300 mg/kg ^{5,6Reference 5Nunes et al. · 2022AnimalAnti-obesity, slimming, biochemical and genotoxic effects of Cordia ecalyculata in diet-induced obese rats — animal in vivo studyView study →Reference 6Araldi et al. · 2014In vitroMutagenic potential of Cordia ecalyculata alone and in association with Spirulina maxima for their evaluation as candidate anti-obesity drugs — in vivo mouse and in vitro studyView study →}, while an earlier mouse study at 2000 mg/kg found no effect and concluded the extract was ineffective for obesity ^{7Reference 7da Silva et al. · 2010AnimalEvaluation of the genotoxic and cytotoxic effects of crude extracts of Cordia ecalyculata and Echinodorus grandiflorus — animal (mouse) in vivo studyView study →}.

The anorectic action is attributed to caffeine never actually quantified in the plant, there is no human trial, and commercial material carries a documented heavy-metal contamination concern.

Chickweed’s weight studies use preparations close to traditional ones. A methanolic extract prevented body-weight and adipose gains in a progesterone-obesity mouse model, and lyophilized juice inhibited pancreatic lipase and amylase in vitro and, at 900 mg/kg in high-fat-diet mice, lowered body weight and lipids, with a proposed GLP-1-release satiety route ^{8,9,10Reference 8Chidrawar et al. · 2011AnimalAntiobesity effect of Stellaria media against drug-induced obesity in Swiss albino mice — animal modelView study →Reference 9Rani et al. · 2012In vitroQuality assessment and anti-obesity activity of Stellaria media (Linn.) Vill. — in vitro & animal modelView study →Reference 10Cho et al. · 2019In vitroEffect of six Korean plants on glucagon-like peptide-1 release — in vitroView study →}.

The signal is not uniform: one study at a lower dose was null ^{11Reference 11Demján et al. · 2020AnimalEffect of Stellaria media tea on lipid profile in rats — animal modelView study →}, effects appear only at high doses in specific rodent models, and no human data exist.

Goat’s rue at 10% of the diet produced significant, sustained weight loss in both normal and genetically obese (ob/ob) mice, an effect pinned to the guanidine alkaloid galegine — the molecule that led to metformin — which activates AMPK and down-regulates fatty-acid synthase and SREBP ^{18,19,20Reference 18Palit et al. · 1999AnimalNovel weight-reducing activity of Galega officinalis in mice — animal modelView study →Reference 19Mooney et al. · 2008In vitroMechanisms underlying the metabolic actions of galegine that contribute to weight loss in mice — animal model / in vitroView study →Reference 20Coxon et al. · 2009AnimalBenzylguanidines and other galegine analogues inducing weight loss in mice — animal modelView study →}.

There is no human weight-loss trial, the effective murine dose is far above realistic human exposure, and galegine is a potent, narrow-margin compound whose content swings several-fold between preparations.

The metabolic signal is isolated-compound and animal only: beta-lapachone prevented weight gain in high-fat-diet and genetically obese mice by driving brown-adipose thermogenesis (UCP1) via AMPK, and an n-butanol taheebo fraction reduced body weight and fat mass in ovariectomized mice ^{35,36Reference 35Kwak et al. · 2019In vitroKwak, H. J., Jeong, M. Y., Um, J. Y., & Park, J. (2019). β-Lapachone regulates obesity through modulating thermogenesis in brown adipose tissue and adipocytes via AMPK signaling — mouse model and in vitro. American Journal of Chinese Medicine, 47(4), 803-822. https://pubmed.ncbi.nlm.nih.gov/31094212/View study →Reference 36Iwamoto et al. · 2016AnimalThe anti-obesity effect of taheebo (Tabebuia avellanedae) extract in ovariectomized mice — animal modelView study →}. This is a mechanistic theme in constituents, not a demonstrated use of the whole bark, and there is no human weight data.

In obese rats guarana reduced body weight, white fat and hepatic steatosis and seed powder inhibited pancreatic lipase in vitro ^{23,24Reference 23Liang et al. · 2023AnimalEffect of guarana on lipid metabolism in obese rats: a lipidomics study — animal modelView study →Reference 24Figueira et al. · 2022In vitroEffect of guarana seed powder on cholesterol absorption in vitro and in Caco-2 cells — in vitroView study →}, yet every positive human weight result comes from caffeine-containing ephedra/yerba-maté combinations whose independent guarana effect cannot be isolated and which carry their own cardiovascular risk ^{25Reference 25Haller et al. · 2005RCTShort-term metabolic and hemodynamic effects of ephedra and guarana combinations — randomised controlled trialView study →}.

No guarana-alone human weight-loss trial exists.