Fat jabs reduce the risk of bowel cancer.
Drugs such as Ozempic and Wegovy have been prescribed to treat type 2 diabetes and suppress appetites in obese individuals but are now thought to provide another major health benefit.
Researchers in the US followed 46,000 patients with type 2 diabetes over a period of 15 years and discovered 94 cancer cases among those who had had the jabs compared to 167 in those who had not been injected.
Professor Rong Xu, one of the authors of the study at Case Western Reserve University in Ohio, said: "To our knowledge this is the first indication this popular class of drugs reduces incidence of colorectal cancer."