RT Journal Article T1 Cold-Induced Thermogenesis Shows a Diurnal Variation That Unfolds Differently in Males and Females. A1 Straat, Maaike E A1 Martinez-Tellez, Borja A1 Sardjoe Mishre, Aashley A1 Verkleij, Magdalena M A A1 Kemmeren, Mirjam A1 Pelsma, Iris C M A1 Alcantara, Juan M A A1 Mendez-Gutierrez, Andrea A1 Kooijman, Sander A1 Boon, Mariëtte R A1 Rensen, Patrick C N K1 brown adipose tissue K1 cardiometabolic health K1 circadian rhythm K1 cold stimulus K1 gender differences K1 metabolism AB Cold exposure mobilizes lipids to feed thermogenic processes in organs, including brown adipose tissue (BAT). In rodents, BAT metabolic activity exhibits a diurnal rhythm, which is highest at the start of the wakeful period. We investigated whether cold-induced thermogenesis displays diurnal variation in humans and differs between the sexes. This randomized crossover study included 24 young and lean male (n = 12) and female (n = 12) participants who underwent 2.5-hour personalized cooling using water-perfused mattresses in the morning (7:45 am) and evening (7:45 pm), with 1 day in between. We measured energy expenditure (EE) and supraclavicular skin temperature in response to cold exposure. In males, cold-induced EE was higher in the morning than in the evening (+54% ± 10% vs +30% ± 7%; P = 0.05) but did not differ between morning and evening in females (+37% ± 9% vs +30% ± 10%; P = 0.42). Only in males, supraclavicular skin temperature upon cold increased more in morning than evening (+0.2 ± 0.1 °C vs -0.2 ± 0.2 °C; P = 0.05). In males, circulating free fatty acid (FFA) levels were increased after morning cold exposure, but not evening (+90% ± 18% vs +9% ± 8%; P  Cold-induced thermogenesis is higher in morning than evening in males; however, lipid metabolism is more modulated in the morning than the evening in females. PB Oxford University Press YR 2022 FD 2022-02-18 LK http://hdl.handle.net/10668/20392 UL http://hdl.handle.net/10668/20392 LA en NO Straat ME, Martinez-Tellez B, Sardjoe Mishre A, Verkleij MMA, Kemmeren M, Pelsma ICM, et al. Cold-Induced Thermogenesis Shows a Diurnal Variation That Unfolds Differently in Males and Females. J Clin Endocrinol Metab. 2022 May 17;107(6):1626-1635. DS RISalud RD Apr 11, 2025