Elsevier

Clinical Nutrition

Volume 40, Issue 10, October 2021, Pages 5311-5321
Clinical Nutrition

Randomized Control Trials
Diurnal variations of cold-induced thermogenesis in young, healthy adults: A randomized crossover trial

https://doi.org/10.1016/j.clnu.2021.08.010Get rights and content
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Summary

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 time-optimized.

Methods

A randomized crossover experiment was designed to examine whether CIT shows morning/evening variation in young, healthy adults (n = 14, 5 women). On the first experimental day, subjects' shivering thresholds were determined following a cooling protocol. After ≈96 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 = 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 = 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.

Registered under ClinicalTrials.gov Identifier no. NCT02365129.

Keywords

Biological clock
Brown fat
Chronobiology
Energy metabolism
Heat loss
Thermogenesis

Abbreviations

AUC
area under the curve
BAT
brown adipose tissue
CHOox
carbohydrate oxidatino
CIT
cold-induced thermogenesis
FATox
fat oxidation
NUTox
nutrient oxidation rates
PROox
protein oxidation
REE
resting energy expenditure
RER
respiratory exchange ratio
TEE
total energy expenditure

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