I have researched for scientific study-based support for most of the herbs used in weight loss formulations in Ayurveda and Traditional Chinese medicine.
To give you a flavor of the scientific evidence for these, I am sharing some key findings for a couple of the popular weightloss formulations:
The plant lowered body weight and reduced fat mass in humans. (Heymsfield et al., 1998) Visceral fat accumulation reduces with Garcinia cambogia extracts. (Hayamizu et al., 2003)
The primary ingredients in this product are caffeine, extracts of Alchemilla vulgaris (lady’s mantle), Oleo europea (wild olive), Cuminum cyminum (cumin), Mentha longifolia (wild mint), and Coffea canephora (coffee bean).
Cumin taken for eight weeks by overweight subjects has the same effects as Orlistat 120 on weight and BMI. Beneficial effects on insulin metabolism were comparable to those of orlistat 120. (Taghizadeh et al., 2015)
The green decaffeinated coffee extract possesses fat-burning action via a glucose metabolism mechanism. (Blum et al., 2007)
My analysis has shown that many of the herbal formulations do show weight loss properties. However, all the scientific evidence that I could find has not been robustly tested in human clinical trials. Until these trials are not undertaken, the evidence supporting these formulations should be regarded to be tentative.