Brown adipose tissue is involved in diet-induced thermogenesis and whole-body fat utilization in healthy humans

Abstract

Background/Objectives:Brown adipose tissue (BAT) is a potential therapeutic target against obesity and diabetes through thermogenesis and substrate disposal with cold exposure. The role of BAT in energy metabolism under thermoneutral conditions, however, remains controversial. We assessed the contribution of BAT to energy expenditure (EE), particularly diet-induced thermogenesis (DIT), and substrate utilization in human adults.Methods:In this cross-sectional study, BAT activity was evaluated in 21 men using 18F-fluoro-2-deoxy-D-glucose positron emission tomography combined with computed tomography (18F-FDG-PET/CT) after cold exposure (19 °C). The subjects were divided into BAT-positive (n=13) and BAT-negative (n=8) groups according to the 18F-FDG-PET/CT findings. Twenty-four hour EE, DIT and respiratory quotient were measured using a whole-room indirect calorimeter at 27 °C.Results:Body composition, blood metabolites and 24-h EE did not differ between groups. DIT (%), calculated as DIT divided by total energy intake, however, was significantly higher in the BAT-positive group (BAT-positive: 9.7±2.5%, BAT-negative: 6.5±4.0%, P=0.03). The 24-h respiratory quotient was significantly lower (P=0.03) in the BAT-positive group (0.861±0.027) than in the BAT-negative group (0.889±0.024).Conclusion:DIT and fat utilization were higher in BAT-positive subjects compared to BAT-negative subjects, suggesting that BAT has a physiologic role in energy metabolism.

Determining the Accuracy and Reliability of Indirect Calorimeters Utilizing the Methanol Combustion Technique

“…A difference in RER of 0.02 can be detected in the accurate instruments; however, those with a %RE worse than 2% could easily mask that small biological difference. A similar case can be made for DIT because significant, but small, differences are often reported …”

Disruption of beta3 adrenergic receptor increases susceptibility to DIO in mouse

“…2011). Thereby, adult human BAT represents a promising target for anti-obesity therapeutic strategies, however, its physiological relevance remains controversial (Cinti 2006, Hibi et al . 2016).…”

MRI characterization of brown adipose tissue under thermal challenges in normal weight, overweight, and obese young men

“…The presence of BAT in adult humans and its potential role in human metabolism were recently recognized. Published data indicate that whole‐body energy expenditure is increased to a greater extent after cold exposure (cold‐induced thermogenesis) and food intake (diet‐induced thermogenesis) in individuals with active BAT shown on 18F‐fluoro‐2‐deoxy‐glucose ( 18 F‐FDG) positron emission tomography and computed tomography (PET/CT) images, than in those without active BAT . Increasing evidence suggests that human BAT may play a role in glucose metabolism and insulin sensitivity and may protect against obesity development …”

“…Published data indicate that whole-body energy expenditure is increased to a greater extent after cold exposure (cold-induced thermogenesis) and food intake (diet-induced thermogenesis) in individuals with active BAT shown on 18F-fluoro-2-deoxy-glucose ( 18 F-FDG) positron emission tomography and computed tomography (PET/CT) images, than in those without active BAT. [4][5][6] Increasing evidence suggests that human BAT may play a role in glucose metabolism and insulin sensitivity and may protect against obesity development. [6][7][8] Compared with white adipocytes, brown adipocytes consist of multilocular lipid droplets with abundant ironcontaining mitochondria and cytoplasm.…”

“…[4][5][6] Increasing evidence suggests that human BAT may play a role in glucose metabolism and insulin sensitivity and may protect against obesity development. [6][7][8] Compared with white adipocytes, brown adipocytes consist of multilocular lipid droplets with abundant ironcontaining mitochondria and cytoplasm. Depots of brown adipocytes also have a larger capillary network than white adipocytes due to their higher oxygen consumption and metabolic activity.…”