Background: Brown adipose tissue (BAT) was considered essentially nonexistent in adults until recent evidence obtained using 18-fluorodeoxyglucose (18-FDG) positron emission tomography/ computed tomography. It seems to play a role in whole body metabolism, but it has not been evaluated in underweight conditions, such as in young females with constitutional leanness (CL) or anorexia nervosa (AN). Subjects and Methods: Thirty-eight subjects were evaluated from October 2011 to March 2012 : 7 CL (21.7 _ 3.6 y, body mass index [BMI] 16.2 _ 1.0 kg/m2), 7 AN (23.4 _ 4.5 y, BMI 15.5 _ 0.8), 3 of the 7 AN after stable refeeding (R-AN, 21.3_1.5 y, BMI 18.8_1.1), and 24 normal weight (NW) women (25.6_3.9 y, BMI 22.2_1.5). Fasting resting metabolic rate and respiratory quotient were measured by indirect calorimetry, body composition by bioimpedentiometry (only in CL, AN, and refed AN), and BAT activity by 18-FDG positron emission tomography/computed tomography scan, all in standardized conditions. Results: All CL (100%), none of the AN and refed AN (0%), and 3 of the 24 NW (12%) subjects showed FDG uptake. Average FDG maximum standardized uptake value was 11.4_6.7 g/mL in CL and 5.5_1.2 g/mL (min 3.7, max 8.3) in the 3NWsubjects. In CL, themaximumstandardized uptake value was directly correlated to resting metabolic rate, corrected for fat-free mass, and inversely correlated with respiratory quotient. Conclusion: BAT activity has been shown in CL in resting thermoneutral conditions and may exert a role against adipose tissue deposition.
Evidence of Brown Fat Activity in Constitutional Leanness
PACE, Leonardo;
2013-01-01
Abstract
Background: Brown adipose tissue (BAT) was considered essentially nonexistent in adults until recent evidence obtained using 18-fluorodeoxyglucose (18-FDG) positron emission tomography/ computed tomography. It seems to play a role in whole body metabolism, but it has not been evaluated in underweight conditions, such as in young females with constitutional leanness (CL) or anorexia nervosa (AN). Subjects and Methods: Thirty-eight subjects were evaluated from October 2011 to March 2012 : 7 CL (21.7 _ 3.6 y, body mass index [BMI] 16.2 _ 1.0 kg/m2), 7 AN (23.4 _ 4.5 y, BMI 15.5 _ 0.8), 3 of the 7 AN after stable refeeding (R-AN, 21.3_1.5 y, BMI 18.8_1.1), and 24 normal weight (NW) women (25.6_3.9 y, BMI 22.2_1.5). Fasting resting metabolic rate and respiratory quotient were measured by indirect calorimetry, body composition by bioimpedentiometry (only in CL, AN, and refed AN), and BAT activity by 18-FDG positron emission tomography/computed tomography scan, all in standardized conditions. Results: All CL (100%), none of the AN and refed AN (0%), and 3 of the 24 NW (12%) subjects showed FDG uptake. Average FDG maximum standardized uptake value was 11.4_6.7 g/mL in CL and 5.5_1.2 g/mL (min 3.7, max 8.3) in the 3NWsubjects. In CL, themaximumstandardized uptake value was directly correlated to resting metabolic rate, corrected for fat-free mass, and inversely correlated with respiratory quotient. Conclusion: BAT activity has been shown in CL in resting thermoneutral conditions and may exert a role against adipose tissue deposition.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
