Brown fat, or brown adipose tissue, is a type of body fat that burns calories to produce heat, which is the opposite of white fat, the tissue that stores extra calories. In adults it is usually found around the neck, armpits and chest. It helps newborns stay warm, and scientists once thought it disappeared after infancy until researchers reported it in adults in 2009.
In a study published in Nature on October 14, 2026, a team led by Paul Cohen of The Rockefeller University used an AI model to measure active brown fat on PET/CT scans from more than 100,000 people treated at Memorial Sloan Kettering Cancer Center. People with more active brown fat were less affected by several conditions, including type 2 diabetes, depression and anxiety. Because the study looked back at existing records, outside experts say it shows a link but does not yet prove that brown fat causes these benefits.
Image: PET/CT scan showing active brown fat in the neck, shoulders and along the spine, by Hg6996, public domain, via Wikimedia Commons.