A Nature study published October 14, 2026 combined artificial-intelligence analysis of scans and medical records from more than 100,000 cancer patients with laboratory and mouse experiments. Greater brown-fat activity was associated with better cardiometabolic health, while losartan activated brown fat in cells and mice. The work does not show that losartan improves metabolism through brown fat in people.
What changed
Researchers analyzed PET/CT scans that can reveal metabolically active brown adipose tissue and compared activity across six fat depots with more than 500 diagnostic codes. Higher activity—especially near the armpit—tracked with more favorable cardiometabolic patterns. Patients taking angiotensin-receptor blockers also showed more brown-fat activity. Follow-up experiments found that losartan increased metabolic activity in cultured brown-fat cells; healthy treated mice increased energy expenditure and oxygen consumption without losing weight.
How strong is the evidence?
The human dataset is unusually large, and the cell and animal work adds biological plausibility. But the human component is retrospective and observational. Medication use was not randomized, so health differences or prescribing patterns could partly explain the association.
What remains uncertain
The imaging population consisted of people evaluated for cancer, which limits generalization. The study did not test whether losartan activates brown fat, raises energy expenditure, causes weight loss, or prevents cardiovascular disease in humans. Mouse metabolic changes often fail to translate clinically, and losartan can affect blood pressure, kidney function, and potassium.
Why it matters
Brown fat may become a useful metabolic target, but this remains a research direction—not a reason to start, stop, or switch blood-pressure medication. A prospective randomized human trial is needed.
Sources
Original Nature study · NIH report
Illustrative stock photograph by Mockup Graphics on Unsplash; it does not depict study participants, brown-fat imaging, or the experimental results.
