Losartan Linked to Active Brown Fat in Study

Researchers found patients taking the blood pressure drug losartan were more likely to show metabolically active brown fat on scans.

Updated on Nov. 3, 2026 in Weight Loss

Isometric editorial illustration of a glass beaker of amber liquid beside rounded orange-brown geometric forms on a pale steel surface, suggesting metabolic tissue. — A study of 101,243 cancer patients found those taking the blood pressure drug losartan were more likely to show active brown fat on PET scans. AI Illustration. Upload story photo >

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A study of 101,243 cancer patients' medical records found losartan users were more likely to have brown fat active on PET scans. Mouse experiments indicated losartan raised energy use and oxygen consumption through a pathway separate from blood pressure lowering.

Why it matters

Brown fat burns energy rather than storing it, and people with it showed lower odds of type 2 diabetes and chronic ischemic heart disease in the data. The findings point to a possible new route for existing drugs to affect metabolism, though the link is association only.

The study drew on medical records of 101,243 cancer patients, with brown fat appearing in 8,897 (just under 9%), and losartan use slightly higher among those with brown fat (2.4% vs. 1.9%). Whether these associations lead to real health benefits remains unknown until prospective studies in people are completed.

The players

Memorial Sloan Kettering Cancer Center

A major New York cancer treatment and research institution that supplied the PET scan records used in the study.

Rockefeller University

A New York research university where the study was led and which is known for its biomedical research programs.

Weill Cornell Medicine

The medical school of Cornell University, where the study's first author holds a post.

The details

Losartan turned on PPAR-gamma, a master switch for fat cells, and a breakdown product of the drug rather than its blood pressure receptor blocking action appeared to drive the brown fat effect. Brown fat was identified by its uptake of the sugar tracer used in PET scans, and was more common in women, younger patients, and on colder days.

Records from 2018 to 2024 were pulled from Memorial Sloan Kettering PET scans for the study.
Medications taken in the month before each scan were recorded and checked.

Health Landscape

Brown fat research has grown from identifying the tissue on PET scans, which Memorial Sloan Kettering's imaging archive helped make possible at scale. This study extends that work by connecting an existing blood pressure drug to the tissue's activity.

For people already taking losartan for blood pressure, this study does not suggest any change in treatment, since the brown fat link is an association seen in records and animal work. Any decision about the drug should remain with a prescribing clinician.

The takeaway

Brown fat activity may be influenced by commonly prescribed drugs, but whether that changes health outcomes in people remains to be tested. Readers should not alter medication based on these early findings.