atty acids (FA) are important substrates for brown adipose tissue (BAT)
metabolism, however, it remains unclear whether there exists a
difference in FA metabolism of BAT between lean and obese healthy
humans. In this study we evaluated supraclavicular BAT fatty acid uptake
(FAU) along with blood perfusion in lean and obese subjects during cold
exposure and at room temperature using positron emission tomography
(PET)/computed tomography (CT). Additionally, tissue samples were taken
from supraclavicular region (typical BAT region) from a subset of
subjects to evaluate histological presence of BAT. Non-shivering cold
stress elevated FAU and perfusion of BAT in lean, but not in obese
subjects. Lean subjects had greater FAU in BAT compared to obese
subjects during cold exposure and interestingly also at room
temperature. The higher BAT FAU was related to younger age and several
indicators of superior systemic metabolic health. The subjects who
manifested BAT histologically had several folds higher BAT FAU compared
to subjects with no such histological manifestation. Together, obese
subjects have less active tissue in supraclavicular region both in basal
and cold-activated state and the FA metabolism of BAT is blunted in
obesity.