Brown Adipose Tissue Prevalence Is Lower in Obesity but Its Metabolic Activity Is Intact

Abstract

Due to its high metabolic activity, brown adipose tissue (BAT) has become a promising target for the development of novel treatment concepts for metabolic disease. Despite several reports of a negative association between the presence of active BAT and obesity, very little is known about the quantitative and qualitative differences of BAT in lean and obese individuals. Systematic studies directly comparing cold-induced BAT activity in leanness and obesity are currently lacking. Here we studied BAT mass and function in 31 lean and 64 obese men and women. After a standardized cooling protocol using a water-perfused vest, 18F-FDG-positron emission tomography/computed tomography scans were performed, and BAT was delineated using lean body-mass adjusted standardized uptake value (SUV) thresholds in anatomic regions with fat radiodensity. Cold-induced thermogenesis (CIT), a functional readout of BAT activity, was quantified by indirect calorimetry. Active BAT was present in a significantly higher proportion of lean than obese individuals (58% vs. 33%, p=0.019). In these participants with active BAT, however, BAT volume and activity did not differ between leanness and obesity. Accordingly, CIT was similar in both weight groups. BAT metrics were not related to adiposity or total fat mass per se. However, in obese participants a strong negative correlation existed between visceral adipose tissue and BAT volume, 18F-FDG uptake and CIT. In summary, despite a significantly lower prevalence of BAT, the metabolic activity and thermogenic capacity of BAT appears to be still intact in obesity and is inversely associated with visceral fat mass.

D-Chiro-Inositol and Myo-Inositol Induce WAT/BAT Trans-Differentiation in Two Different Human Adipocyte Models (SGBS and LiSa-2)

“…These findings support the recommendation to further test both the isomers and/or their combination in preclinical studies to investigate whether these molecules can have positive effects in weight loss. Indeed, recent observations from Kulterer and coworker [ 56 ] demonstrated that BAT is less frequently detected in obese rather than in lean people. They also highlighted that BAT is associated with visceral adiposity rather than with total body fat content per se.…”

Browning of white adipose tissue may be an appropriate adaptive response to critical illness

“…5 An inverse correlation exists between the amount of BAT and the body mass index, percentage of total body fat, and volume of WAT. 19 Greater activity of BAT is associated with less fat content within WAT, subcutaneous fat depots, and the liver. 5,37 The WAT in patients with obesity has less capability for releasing interleukin 13 compared with that in their lean counterparts, which would subsequently result in reduced conversion of macrophages from the M1 to the M2 phenotype.…”

“…18 Increasing amounts of BAT are associated with reduced body mass index and visceral adipose tissue. 5,19 Those who have a greater amount or larger deposits of BAT tend to have less fat content in their visceral adipose tissue, subcutaneous fat tissue, or liver. 5 BAT is characterized by the increased expression of UCP-1, which causes the uncoupling of the electron transport chain from the synthesis of ATP.…”

Lipid Peroxidation in Obesity: Can Bariatric Surgery Help?

“…BAT also has a role in adiposity and its metabolic activity is inversely related to BMI [ 14 , 15 ]. Although the prevalence of active BAT decreases with obesity [ 16 ], a recent study reported that obese individuals with active BAT have a healthier metabolic phenotype [ 17 ]. Besides white and brown adipocytes, today we also recognize beige, pink, and yellow adipocytes, all with distinct functions that are described elsewhere [ 18 ].…”