Obesogens are foreign chemical compounds that disrupt normal development and balance of lipid metabolism, which in some cases, can lead to obesity. Obesogens may be functionally defined as chemicals that inappropriately alter lipid homeostasis and fat storage, change metabolic setpoints, disrupt energy balance or modify the regulation of appetite and satiety to promote fat accumulation and obesity.There are many different proposed mechanisms through which obesogens can interfere with the body's adipose tissue biology. These mechanisms include alterations in the action of metabolic sensors; dysregulation of sex steroid synthesis, action or breakdown; changes in the central integration of energy balance including the regulation of appetite and satiety; and reprogramming of metabolic setpoints. Some of these proposed pathways include inappropriate modulation of nuclear receptor function which therefore allows the compounds to be classified as endocrine disrupting chemicals that act to mimic hormones in the body, altering the normal homeostasis maintained by the endocrine system.Obesogens have been detected in the body both as a result of intentional administration of obesogenic chemicals in the form of pharmaceutical drugs such as diethylstilbestrol, selective serotonin reuptake inhibitor, and thiazolidinedione and as a result of unintentional exposure to environmental obesogens such as tributyltin, bisphenol A, diethylhexylphthalate, and perfluorooctanoate. Emerging evidence from laboratories around the world suggests that other chemicals will be confirmed as falling under this proposed classification in the near future, and that there may be some serious biological effects due to exposure to these chemicals that still remain undiscovered. Until now, 20 chemicals have been found responsible for making one fat.The term obesogen was coined by Felix Grün and Bruce Blumberg of the University of California, Irvine. The topic of this proposed class of chemical compounds and how to counteract their effects is explored at length in the book The New American Diet. Paula Baillie-Hamilton, a doctor in the UK, was the first one to have identified how obesogens make it difficult to lose weight. She published her results in the Journal of Alternative and Complementary Medicine in 2002.