Semaglutide the active drug is called glucagon-like peptide-1. GLP-1 is a natural compound that's released from your gastrointestinal tract after you consume a meal. It acts to stimulate insulin secretion, which is why it helps for type 2 diabetes, but it also acts in the brain to terminate food intake or to signal satiety. These drugs take that natural form of GLP-1 and they make it much more stable and active. This clinical form is called semaglutide. When you administer semaglutide to an individual with severe obesity, it curbs their appetite, and they essentially don't feel the need to eat as drastically. It also reduces cravings for highly palatable foods. It's been very effective at reducing body weight.

Tirzepatide is a dual agonist for the glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors similar to Mounjaro. The drug leads to significantly improved glycemic control and weight reduction in patients with T2DM, maximizing benefits similar to GLP-1 medications such as semaglutide.

The GLP-1 receptor is expressed throughout the brain in many different regions, so these drugs can have a variety of effects in addition to their ability to reduce feeding. In terms of side effects, oftentimes, people report nausea and vomiting. These drugs also slow gastric emptying, so they slow the food passage through the GI tract. This can sometimes lead to feelings of nausea or a condition called gastroparesis.

Unfortunately, as soon as people stop the medication, they often will regain the weight. This is true not just for drugs, but also for dieting or bariatric surgery. Regaining weight is thought to occur because there are circuits in the brain that have a sense of your body weight “set point.” Once you stop taking these drugs, feeding often increases until the body weight goes back to the previous set point that you were at before taking the drugs. The mechanisms behind this weight rebound effect are still a very active area of research. 

These are life-saving drugs for individuals with type 2 diabetes. They're really game-changing for individuals with very severe obesity and they work really well in those conditions. However, they're not necessarily intended just for losing a few pounds. There are other strategies such as dieting and exercise, which still should be your first options.