Researchers at College of Health and Biomedicine, Victoria University in Melbourne, Victoria, Australia conducted a systematic review of plant-derived appetite-suppressing supplements used for weight loss and weight management including Camellia sinensis, Caralluma fimbriata, Citrus aurantium, Coleus forskohlii, Garcinia cambogia, and Phaseolus vulgaris.  Authors say that many isolated compounds or extracts provide therapeutic effects like appetite control and weight loss, but more research is needed to "define the magnitude of the effects, optimal dosage, mechanisms of action, long term safety, and potential side effects."

Reference

Astell KJ1, Mathai ML, Su XQ.  A review on botanical species and chemical compounds with appetite suppressing properties for body weight control.  Plant Foods Hum Nutr. 2013 Sep;68(3):213-21.

Another review conducted by researchers in India also suggests that some medicinal plants may be used to treat obesity.  They include Achyranthus aspera, Camellia sinensis, Emblica officinalis, Garcinia cambogia, and Terminalia arjuna among others.  Some phytochemicals including escins, perennisosides, dioscin, gracillin, and various plant extracts such those from Nelumbo nucifera, Panax japonicas, Cichorium intybus, Cyperus rotundus, and Paeonia suffruticosa have been identified to be effective therapeutics indicated for the treatment of obesity.

Reference

Neeru Vasudeva, Neerja Yadav, Surendra Kumar Sharma, Natural products: A safest approach for obesity, Chinese Journal of Integrative Medicine, June 2012, Volume 18, Issue 6, pp 473-480