Weather permitting: Increased seasonal efficiency of nonshivering thermogenesis through brown adipose tissue activation in the winter

Abstract

Objectives We investigated seasonal changes in brown adipose tissue (BAT) activation and metabolism in a temperate‐climate Albany, NY population. Methods Data were collected among 58 participants (21 males, 37 females, ages: 18–51) in the summer and 59 participants (23 males, 36 females, ages: 18–63) in the winter in Albany, New York. BAT activity was inferred by comparing metabolic rate, heat dissipation in the supraclavicular area, and respiratory quotient at room temperature and cold exposure. Seasonal variation in BAT was determined by comparing these measurements from summer and winter. Results At mild cold exposure, heat dissipation of the supraclavicular area was significantly greater in the winter compared to summer (p < .001); however, no significant differences were found between seasons in metabolic rate measurements. This suggests BAT activation may be metabolically more efficient in the winter, due to prolonged lower seasonal temperatures relative to summer. Respiratory quotient significantly increased upon mild cold exposure in the winter compared to summer (p < .001). While carbohydrate utilization increased in the winter, fat remained the primary metabolic substrate for BAT activity across both seasons. Conclusion The seasonal variations in the effects of nonshivering thermogenesis on metabolic rate and substrate metabolism suggest a buffering of energy expenditure and an increased use of glucose as fuel by BAT as a result of acclimatization to cold in the winter. These findings point towards a potential role of BAT in human whole‐body mediated glucose disposal and cold adaptation.

When the cold gets under your skin: Evidence for brown adipose tissue activity in Samoan adults

“…Comparing BAT activity between seasons in a New York state sample. Niclou and Ocobock et al (2022) observed that NST through BAT activity during mild cold exposure was increased in the winter months compared to summer. Similarly, a study in Japan demonstrated that individuals with quantifiable BAT activity, measured using PET/CT scanning, at room temperature had greater glucose uptake and fat oxidation in the winter compared to summer, increasing NST during the colder season (Yoneshiro et al, 2016).…”

“…In humans, NST allows for comfortable living in moderately cold conditions and represents one of the principal physiological adaptations to cold (Cannon & Nedergaard, 2004). Due to its heat producing capacity and role in mammalian hibernation, most of our current understanding of BAT activity stems from studies on rodents, human infants, and cold‐adapted or cold‐acclimated human populations (Cannon & Nedergaard, 2004; Himms‐Hagen, 1985; Levy et al, 2018; Niclou & Ocobock, 2022; Ocobock et al, 2022; Yoneshiro et al, 2016). While prior studies have shown BAT activation in temperate climate populations, only recently have groups examined BAT activity in a population rarely exposed to prolonged or seasonal cold (Cypess et al, 2009; van Marken Lichtenbelt et al, 2009; Monfort‐Pires et al, 2022; Niclou & Ocobock, 2022; Yoneshiro et al, 2016).…”

“…Due to its heat producing capacity and role in mammalian hibernation, most of our current understanding of BAT activity stems from studies on rodents, human infants, and cold‐adapted or cold‐acclimated human populations (Cannon & Nedergaard, 2004; Himms‐Hagen, 1985; Levy et al, 2018; Niclou & Ocobock, 2022; Ocobock et al, 2022; Yoneshiro et al, 2016). While prior studies have shown BAT activation in temperate climate populations, only recently have groups examined BAT activity in a population rarely exposed to prolonged or seasonal cold (Cypess et al, 2009; van Marken Lichtenbelt et al, 2009; Monfort‐Pires et al, 2022; Niclou & Ocobock, 2022; Yoneshiro et al, 2016). The present study is the first to explore the effects of BAT on NST by inferring BAT activity through simultaneous measures of metabolic rate and heat dissipation before and during sustained mild cold exposure among Polynesian adults from Samoa.…”

“…The thermogenic capacity of BAT suggests that it may play a role in cold adaptation and may contribute to differences in metabolic responses to cold exposure (Cypess et al, 2009; Lee et al, 2010; Levy et al, 2018; Niclou & Ocobock, 2022). In circumpolar environments, for example, BAT may have contributed to the survival and thriving of humans by providing an additional source of heat production, reducing the energetic costs of shivering and vasoconstriction (Andersen et al, 1960; Hart et al, 1962).…”

Commentary—fat but fit…and cold? Potential evolutionary and environmental drivers of metabolically healthy obesity

“…In a small study conducted among seven males, acute cold exposure elicited a 63% increase in fatty acid utilization and a 588% increase in glucose utilization [ 81 ]. Among the Sakha, glucose levels, but not fatty acid levels, were positively correlated with BAT activity [ 43 ]; a similar preference for glucose utilization was also found among a population of females and males in Albany, NY [ 78 ]. Chondronikola et al [ 82 ] found that the increase in metabolic rate associated with BAT was 70% fueled by free fatty acids and 30% by glucose, while others found an increase in LDL and HDL cholesterol levels [ 83 ]—indicating a high degree of variation in BAT substrate utilization.…”