Tirzepatide May Boost Energy Burning by Activating Brown Fat: Study
Slovenia: A small study presented at ENDO 2026 has revealed that tirzepatide may increase the body's energy expenditure by activating brown adipose tissue (brown fat), a type of fat that burns calories to produce heat. Importantly, this effect appeared to occur independently of weight loss, suggesting that tirzepatide may influence metabolism through mechanisms beyond appetite reduction and weight loss alone. These findings indicate a potential additional pathway by which tirzepatide helps improve metabolic health.
Presenting the findings at ENDO 2026, Dr. Rok Herman, a resident at the University Medical Center Ljubljana, Slovenia, highlighted evidence that tirzepatide can enhance brown adipose tissue (BAT) activity in women with obesity. BAT has attracted growing attention because of its ability to increase energy expenditure and improve metabolic function, making it a promising target for obesity-related therapies.
Although tirzepatide is known to produce substantial weight loss primarily by reducing food intake, its effects on brown adipose tissue (BAT) have not been well understood. To explore this, researchers conducted the 24-week TABFAT trial, a randomized, placebo-controlled study involving 34 women with obesity (median age 39.5 years; median BMI 36.9 kg/m²) who received either once-weekly tirzepatide or placebo.
BAT activity was assessed before and after treatment using cold-stimulated PET/CT scans and MRI. Researchers also measured resting energy expenditure through indirect calorimetry. In a subset of participants with BAT activation, adipose tissue samples were analyzed to evaluate the expression of thermogenic and mitochondrial genes.
Key Findings:
- Tirzepatide increased the proportion of participants with detectable brown adipose tissue (BAT) activity from 41.2% at baseline to 64.7% after treatment, while no significant change was observed with placebo.
- Treatment with tirzepatide significantly increased BAT metabolic activity and metabolically active BAT volume compared with baseline and placebo.
- MRI assessments showed a reduction in supraclavicular BAT fat fraction, supporting the PET/CT findings of enhanced BAT activation.
- Participants receiving tirzepatide experienced a median weight loss of 13.5%.
- Changes in body weight were not associated with changes in BAT activity, indicating that BAT activation occurred independently of weight loss.
- Resting energy expenditure did not differ significantly between the tirzepatide and placebo groups.
- A greater numerical decline in resting energy expenditure was observed among tirzepatide-treated participants who did not show BAT activation.
- Exploratory adipose tissue analyses demonstrated increased expression of thermogenic and mitochondrial genes in participants with tirzepatide-induced BAT activation.
Summarizing the findings, the researchers concluded that tirzepatide can stimulate brown adipose tissue activity in women with obesity regardless of the degree of weight loss achieved. The results point to a potential new mechanism through which tirzepatide may exert metabolic benefits, opening new avenues for understanding and enhancing obesity treatments.
Reference: https://endo2026.endocrine.org/fsPopup.asp?PresentationID=1830669&mode=presInfo
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