@misc{10481/71227,
year = {2021},
month = {8},
url = {http://hdl.handle.net/10481/71227},
abstract = {Background: Harnessing cold-induced thermogenesis (CIT) and brown adipose tissue (BAT) activity has
been proposed as a means of counteracting a positive energy balance, and thus of combating obesity and
its related comorbidities. However, it has remained unclear whether CIT and BAT activity show diurnal
variation in humans - knowledge that might allow treatments based on these factors to be timeoptimized.
Methods: A randomized crossover experiment was designed to examine whether CIT shows morning/
evening variation in young, healthy adults (n ¼ 14, 5 women). On the first experimental day, subjects'
shivering thresholds were determined following a cooling protocol. After z96 h had elapsed, the subjects
then returned on two further days (approx. 48 h apart) at 08:00 h or 18:00 in random order. On
both the latter days, the resting energy expenditure (REE) was measured before the subjects underwent
personalized cold exposure (i.e., according to their shivering threshold). CIT was then assessed for 60 min
by indirect calorimetry. In an independent cross-sectional study (n ¼ 133, 88 women), subjects came to
the laboratory between 8:00 and 18:00 h and their BAT 18F-fluordeoxyglucose (18F-FDG) uptake was
assessed after personalized cold stimulation.
Results: Both the REE and CIT were similar in the morning and evening (all P > 0.05). Indeed, 60 min of
personalized-mild cold exposure in the morning or evening elicited a similar change in energy expenditure
(16.8 ± 12.8 vs. 15.7 ± 15.1% increase above REE, P ¼ 0.72). BAT 18F-FDG uptake was also similar in
the morning, evening and afternoon (all P > 0.05).
Conclusion: CIT does not appear to show morning/evening variation in young healthy adults, with the
current study design and methodology. BAT 18F-FDG uptake appears not to change across the day either,
although experiments with a within-subject study design are needed to confirm these findings.},
organization = {Spanish Ministry of Economy and Competitiveness via the Fondo de Investigacion Sanitaria del Instituto de Salud Carlos III	PI13/01393	
PTA 12264-I},
organization = {Retos de la Sociedad	DEP2016-79512-R},
organization = {European Commission},
organization = {Spanish Government	FPU 13/03410	
FPU 15/04059},
organization = {Fundacion Iberoamericana de Nutricion (FINUT)},
organization = {Redes Tematicas de Investigaci on Cooperativa RETIC network	Red SAMID RD16/0022},
organization = {AstraZeneca},
organization = {University of Granada's Plan Propio de Investigacion},
organization = {Junta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades (ERDF)	SOMM17/6107/UGR},
organization = {Fundacion Alfonso Martin Escudero},
publisher = {Elsevier},
keywords = {Biological clock},
keywords = {Brown fat},
keywords = {Chronobiology},
keywords = {Energy metabolism},
keywords = {Heat loss},
keywords = {Thermogenesis},
title = {Diurnal variations of cold-induced thermogenesis in young, healthy adults: A randomized crossover trial},
doi = {10.1016/j.clnu.2021.08.010},
author = {Acosta Manzano, Francisco Miguel and Sánchez Delgado, Guillermo and Martínez Téllez, Borja Manuel and Alcántara Alcántara, Juan Manuel and Llamas Elvira, José Manuel and Ruiz Ruiz, Jonatan},
}