Globally, people are struggling with obesity. Many effective, non-conventional methods of weight reduction, such as herbal and natural dietary supplements, are increasingly being sought. Fat burners are believed to raise metabolism, burn more calories and hasten fat loss. Despite patient perceptions that herbal remedies are free of adverse effects, some supplements are associated with severe hepatotoxicity. The present report describes a young healthy woman who presented with fulminant hepatic failure requiring emergent liver transplantation caused by a dietary supplement and fat burner containing usnic acid, green tea and guggul tree extracts. Thorough investigation, including histopathological examination, revealed no other cause of hepatotoxicity. The present case adds to the increasing number of reports of hepatotoxicity associated with dietary supplements containing usnic acid, and highlights that herbal extracts from green tea or guggul tree may not be free of adverse effects. Until these products are more closely regulated and their advertising better scrutinized, physicians and patients should become more familiar with herbal products that are commonly used as weight loss supplements and recognize those that are potentially harmful.