How do weight loss drugs work?

Weight loss drugs like phentermine belong to a class of medications known as anorectics, which decrease appetite. The anticonvulsant topiramate is used to decrease appetite and cause feelings of fullness.The combination of drugs like naltrexone (an opiate antagonist) and bupropion (an antidepressant) act on the hunger and reward centers of the brain to reduce appetite and help control cravings.

Tirzepatide is a dual GIP and GLP-1 receptor agonist — it stimulates insulin release and increases levels of the hormone adiponectin, reducing blood glucose and appetite.^[1]

Another weight loss drug, orlistat, prevents the fat (and fat calories) from foods from being absorbed by the intestines — it is known as a lipase inhibitor.