REVIEW ARTICLE Open Access A systematic review of anti-obesity medicinal plants - an update Shirin Hasani-Ranjbar 1,2 , Zahra Jouyandeh 2 and Mohammad Abdollahi 3* Abstract Obesity is the most prevalent health problem affecting all age groups, and leads to many complications in the form of chronic heart disease, diabetes mellitus Type 2 and stroke. A systematic review about safety and efficacy of herbal medicines in the management of obesity in human was carried out by searching bibliographic data bases such as, PubMed, Scopus, Google Scholar, Web of Science, and IranMedex, for studies reported between 30th December 2008 to 23rd April 2012 on human or animals, investigating the beneficial and harmful effects of herbal medicine to treat obesity. Actually we limited our search to such a narrow window of time in order to update our article published before December of 2008. In this update, the search terms were “obesity” and (“herbal medicine” or “plant”, “plant medicinal” or “medicine traditional”) without narrowing or limiting search items. Publications with available abstracts were reviewed only. Total publications found in the initial search were 651. Total number of publications for review study was 33 by excluding publications related to animals study. Studies with Nigella Sativa, Camellia Sinensis, Crocus Sativus L, Seaweed laminaria Digitata, Xantigen, virgin olive oil, Catechin enriched green tea, Monoselect Camellia, Oolong tea, Yacon syrup, Irvingia Gabonensi, Weighlevel, RCM- 104 compound of Camellia Sinensis, Pistachio, Psyllium fibre, black Chinese tea, sea buckthorn and bilberries show significant decreases in body weight. Only, alginate-based brown seaweed and Laminaria Digitata caused an abdominal bloating and upper respiratory tract infection as the side effect in the trial group. No other significant adverse effects were reported in all 33 trials included in this article. In conclusion, Nigella Sativa, Camellia Synensis, Green Tea, and Black Chinese Tea seem to have satisfactory anti- obesity effects. The effect size of these medicinal plants is a critical point that should be considered for interpretation. Although there was no report for side effect in these trials, we believe that safety of these plants still remains to be elucidated by further long-term studies. Keywords: Herbal medicine, Obesity, Systematic review Introduction Obesity is becoming one of the most prevalent health con- cerns among all populations and age groups worldwide, resulting into a significant increase in mortality and morbid- ity related to coronary heart diseases, diabetes type 2, meta- bolic syndrome, stroke and cancers [1-3]. Prevention and treatment of this problem are an important deal for health systems, whose aim is to reduce the obesity and overweight prevalence, and related complications over the world [4]. Both lifestyle and pharmacotherapy interventions have been considered by physicians and other health care professionals as obesity treatment modalities. Studies show that only 5-10 % subjects can maintain their weight loss over the years [5]. The complex pathogenesis of obesity indicates the need of different intervention strategies to confront this problem with a simple drug therapy which is more acceptable to pa- tients [4]. Disappointing results, after cessation the lifestyle modification or pharmacotherapy indicated the need of other treatment modalities to produce better and long- lasting results, in terms of weight loss [6]. Herbal supple- ments and diet-based therapies for weight loss are among the most common n complementary and alternative medi- cine [CAM] modalities [7]. A vast range of these natural products and medicinal plants, including crude extracts and isolated compounds from plants can be used to induce weight loss and prevent diet-induced obesity. In the recent * Correspondence: mohammad@tums.ac.ir 3 Faculty of Pharmacy, and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran, Iran Full list of author information is available at the end of the article © 2013 Hasani-Ranjbar et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Hasani-Ranjbar et al. Journal of Diabetes & Metabolic Disorders 2013, 12:28 http://www.jdmdonline.com/content/12/1/28