You've probably heard that not all body fat is the same. Some fat quietly sits around your waist and stores extra energy. But there's another kind, hidden deep in your neck and chest, that actually burns energy to keep you warm.
That tissue is called brown fat, and a huge new study in Nature found that adults who still have active brown fat were far less likely to have heart disease and type 2 diabetes.
What the study found
Researchers at Rockefeller University and Memorial Sloan Kettering Cancer Center used an AI image-analysis system to review more than a decade of body scans. They looked at 18F-FDG-PET-CT scans taken between June 2009 and July 2024.
These are the standard scans used in cancer care.
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Of the 101,243 adults in the study, 8,709 had detectable active brown fat on their scans.
Compared with matched people without active brown fat, this group had 47 percent lower odds of chronic ischemic heart disease. They also had 58 percent lower odds of type 2 diabetes.
Rates of depression and anxiety were lower in the brown fat group too. According to the Rockefeller University press release, lead author Nicolás Gómez-Banoy sees a possible explanation.
"We know that metabolically healthy people tend to have lower incidence of psychiatric diseases, so it could be that having brown fat makes you more metabolically healthy," he said.
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The findings were published October 14, 2026 in Nature. Because this is an observational study, it shows a strong association, not proof of cause and effect.
Where this good fat sits in the body
Brown fat is not one single lump in one place. The study mapped activity across six locations in the body. These include the neck, above the collarbone, the armpits, around the chest, along the spine, and inside the belly.
Activity in the armpit area had the clearest link to lower blood pressure, Gómez-Banoy noted in the Rockefeller statement.
What is known to activate it
Brown fat burns calories to produce heat, and the main natural trigger is cold. A review in Biology notes that cold exposure around 16 to 19 degrees Celsius (roughly 61 to 66 Fahrenheit) for about two hours can raise glucose uptake in brown fat.
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Longer stretches of mild cold over several days have shown similar effects.
Exercise is less clear. The same review notes that some studies suggest exercise can activate brown fat, while other research shows the opposite.
A surprising drug lead
The researchers also used their AI system to look for medications linked to higher brown fat activity. The common blood pressure drug losartan, an angiotensin receptor blocker, stood out.
In lab tests on brown fat cells and in mice, losartan boosted the UCP1 protein that fuels heat production, and the mice used more energy at rest. Whether losartan does anything similar in people has not been tested in a clinical trial.
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The study has limits. The scans came from a cancer center, so the group may not represent the general population. The scans were also taken without prior cold exposure, meaning the researchers were looking at baseline brown fat, not peak activity.
What this means in practice
If you want to give your brown fat a nudge, the evidence still points to cold. Short daily exposure to cool indoor temperatures or walks in cold weather are the simplest and best-studied ways to activate it.
There is no supplement proven to activate human brown fat, and losartan is a prescription blood pressure drug, not a weight-loss tool. Anyone curious about brown fat and metabolic health should talk to their doctor before changing medications or routines.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.