Comparing supraclavicular brown adipose tissue fat fraction changes between mild cold and thermoneutrality in healthy adults

Brown adipose tissue (BAT) is considered a therapeutic target in cardiometabolic health for its capacity to combust triglyceride-derived fatty acids into heat. Previous MRI studies consistently reported reductions in fat fraction (FF) in supraclavicular BAT (scBAT) after cold exposure. However, there is limited research on the validity of this outcome against thermoneutral conditions. We compared scBAT FF dynamics and thermal perception scores between mild-cold and thermoneutrality. Cold exposure decreased scBAT ΔFF (-0.73±0.19%), accompanied with colder thermal perceptions during cooling. At thermoneutrality, two out of three participants also showed a scBAT ΔFF decrease (-0.39±0.06%), yet normal thermal perceptions were reported.