Tirzepatide has been found to activate brown adipose tissue in addition to aiding weight loss, according to a study presented on June 16 at ENDO 2026, the Endocrine Society's annual meeting in Chicago. The research marks a significant development in obesity research.
Previously, tirzepatide’s effectiveness was attributed mainly to appetite suppression and reduced food intake. Brown adipose tissue, once thought to disappear after infancy and only confirmed in adults through imaging studies in the late 2000s, is known for its role in burning calories but is typically suppressed in individuals with obesity. Moderate cold exposure had been recognized as its strongest activator until now.
In the randomized, placebo-controlled clinical trial involving premenopausal women with obesity, researchers led by Herman used cold-stimulated PET/CT imaging and MRI scans over a 24-week period to assess changes before and after treatment. "We found that tirzepatide significantly increased brown adipose tissue activity and volume, and it also showed potential signs of converting white subcutaneous fat into more metabolically active 'beige' fat," Herman said.
The study reported that PET/CT-detectable brown adipose tissue activity rose from 41.2% to 64.7% of participants treated with tirzepatide, while no similar change occurred in the placebo group. "We were also encouraged by the consistency of the signal across other imaging modalities employed in the study that may capture different components of brown fat biology," Herman said.
"This adds a new layer to how we understand the new generation of anti-obesity medications," Herman said. "They are not only appetite suppressants—tirzepatide also appears to modulate energy expenditure at the tissue level, opening a plausible path toward future therapies that combine appetite regulation with thermogenic activation." Herman suggested future research should measure and potentially enhance use of brown and beige fat activity as targets for tailored obesity care.
