The Importance of Brown Adipose Tissue

To the Editor: In the April 9 issue, van Marken Lichtenbelt et al., 1 Cypess et al., 2 and Virtanen et al. 3 report on functioning supraclavicular brown adipose tissue in adult humans. Van Marken Lichtenbelt et al. conclude that brown-adipose-tissue activity induced by exposure to cold is impaired in overweight healthy subjects, and Cypess et al., using epidemiologic-association techniques, conclude that older subjects and those with a higher body-mass index (BMI) have less brown adipose tissue. It is suggested that obesity is associated with reduced brown-adipose-tissue function or activity. However, disseminated brown adipocytes 4 within the large subcutaneous adipose-tissue mass may cumulatively represent . . .