is an oral superabsorbent hydrogel used for weight loss in the treatment of obesity and overweight. As Gelesis100 absorbs water, it expands in the stomach and small bowel, which may result in satiety. Gelesis100 was approved in April 2019 by the US Food and Drug Administration as a medical device. In 2022, the American Gastroenterology Association recommended the use of Gelesis100 be limited to clinical trials due to limited evidence. Withdrawn Lorcaserin Lorcaserin (Belviq) was approved 28 June 2012 for obesity with other co-morbidities. The average weight loss by study participants was modest, but the most common side effects of the medication are considered benign. It reduces appetite by activating a type of serotonin receptor known as the 5-HT2C receptor in a region of the brain called the hypothalamus, which is known to control appetite. This drug has now been withdrawn from the market because a safety clinical trial shows an increased occurrence of cancer. Sibutramine Sibutramine (Meridia), which acts in the brain to inhibit deactivation of the neurotransmitters, thereby decreasing appetite was approved in 1997 and withdrawn from the United States and Canadian markets in October 2010 due to cardiovascular concerns. As late as 2004, some held that Meridia was a harmless medication for fighting obesity: the US District Court of the Northern District of Ohio rejected 113 cases complaining about the negative effects of the medication, stating that the clients lacked supporting facts and that the representatives involved were not qualified enough. In October Sibutramine was withdrawn from the market for cardiovascular side effects like stroke or heart attack, sometimes fatal, in the United States, the UK, the EU, Australia, Canada, Hong Kong and Colombia. Rimonabant Rimonabant (also known as SR141716; trade names Acomplia and Zimulti) was an anorectic antiobesity medication that was first approved in Europe in 2006 but was withdrawn worldwide in 2008 due to serious psychiatric side effects; it was never approved in the United States. It works via a specific blockade of the endocannabinoid system. It has been developed from the knowledge that cannabis smokers often experience hunger, which is often referred to as "the munchies". Rimonabant is an inverse agonist for the cannabinoid receptor CB1 and was the first medication approved in that class. Off label and experimental medications Metformin In people with type 2 diabetes mellitus and for those taking clozapine for schizophrenia, the medication metformin (Glucophage) can reduce weight, but in