Keep cool and stay lean

Numerous studies demonstrate the continuous growing pandemic of obesity. Obesity is the result of an imbalance between energy intake and energy expenditure. Tissues able to combust excess calories are an interesting target in the battle against obesity. The main aim of this thesis is to focus on tissues able to burn off calories.
The first part of this thesis focuses on brown adipose tissue (BAT). Activation of BAT by cold results in the production of heat, and during this process, significant amounts of energy are dissipated. The prevalence of metabolically active BAT decreases with increasing BMI, underlining the potential role of BAT in energy balance. Metabolically active BAT is generally visualized with ¹⁸F-FDG positron emission tomography computed tomography (PET-CT). ¹⁸F-FDG PET-CT imaging pinpoint areas with high glucose turnover.
BAT shows physiological uptake of ¹⁸F-FDG in 2­9% of the primary diagnostic ¹⁸F-FDG PET-CT scans. Physiological ¹⁸F-FDG uptake is also frequently seen in the colon. Approximately half of the patients who underwent a diagnostic ¹⁸F-FDG PET-CT scan show physiological uptake of ¹⁸F-FDG in the colon, suggesting that the colon has a comparatively high glucose consumption. Therefore, the second part of this thesis focuses on the colon as a potential target to combust calories.