Related Experiment Video
Updated: May 20, 2026

Using a Combination of Indirect Calorimetry, Infrared Thermography, and Blood Glucose Levels to Measure Brown Adipose Tissue Thermogenesis in Humans
Published on: June 2, 2023
Fasting and postprandial activity of brown adipose tissue in healthy men
Anne Vrieze1, Josefine E Schopman, Wanda M Admiraal
1Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands. a.vrieze@amc.uva.nl
Unlabelled:
The role of brown adipose tissue (BAT) in adult metabolism is poorly understood. This study aimed to examine the differential effects of an overnight fast and the postprandial state on BAT activity.
Methods:
We included 10 healthy, lean male volunteers. BAT uptake of glucose was visualized using (18)F-FDG PET/CT during mild cold exposure. Each subject underwent PET/CT twice. The first scan was obtained after an overnight fast; the second after a standardized meal.
Results:
(18)F-FDG uptake in BAT was observed in 6 of 10 volunteers. These subjects were found to have a higher maximal standardized uptake value when fasting (median, 13.1 g/mL; range, 6.1-27.6 g/mL) than when in the postprandial state (median, 6.8 g/mL; range, 2.1-13.4 g/mL) (P = 0.03).
Conclusion:
Cold-stimulated (18)F-FDG uptake by BAT in humans is more pronounced during fasting. The lower maximal standardized uptake value in the postprandial state may be explained by increased insulin-stimulated glucose uptake in muscle.
Related Concept Videos
Metabolic States of the Body: The Postabsorptive State
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...
Metabolic States of the Body: Fasting and Starvation
Metabolic States of the Body: The Absorptive State

