Fighting fat with fat
Brown adipose tissue (BAT) has been identified as a potential target in the fight against obesity. BAT is abundant in newborns and stores of this tissue naturally decrease with age. Recent studies have identified a link between adults with detectable levels of brown fat and reduced rate of obesity. Strategies that increase BAT levels in adults may be necessary to combat expanding waistlines. Anouk van der Lans and colleagues and Takeshi Yoneshiro and colleagues investigated methods for increasing BAT in adults. Both groups show that a regimen of daily exposure to cold temperatures increased both brown adipose tissue and metabolic rates. Additionally, Yoneshiro and colleagues showed that daily ingestion of capsinoids, the compounds found in spicy chiles, also increased metabolic activity. The image on the left from Yoneshiro and colleagues shows FDG-PET/CT scans from an individual before (right scan) and 6 weeks after (left scan) a daily cold exposure regime. The red areas on either side of the neck indicate BAT activity. The image on the left from van der Lans and colleagues shows PET/CT fusion (color) and FDG-PET images (black and white) of a subject before (top) and after (bottom) cold acclimation.
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Abstract
In recent years, it has been shown that humans have active brown adipose tissue (BAT) depots, raising the question of whether activation and recruitment of BAT can be a target to counterbalance the current obesity pandemic. Here, we show that a 10-day cold acclimation protocol in humans increases BAT activity in parallel with an increase in nonshivering thermogenesis (NST). No sex differences in BAT presence and activity were found either before or after cold acclimation. Respiration measurements in permeabilized fibers and isolated mitochondria revealed no significant contribution of skeletal muscle mitochondrial uncoupling to the increased NST. Based on cell-specific markers and on uncoupling protein-1 (characteristic of both BAT and beige/brite cells), this study did not show “browning” of abdominal subcutaneous white adipose tissue upon cold acclimation. The observed physiological acclimation is in line with the subjective changes in temperature sensation; upon cold acclimation, the subjects judged the environment warmer, felt more comfortable in the cold, and reported less shivering. The combined results suggest that a variable indoor environment with frequent cold exposures might be an acceptable and economic manner to increase energy expenditure and may contribute to counteracting the current obesity epidemic.
Authors
Anouk A.J.J. van der Lans, Joris Hoeks, Boudewijn Brans, Guy H.E.J. Vijgen, Mariëlle G.W. Visser, Maarten J. Vosselman, Jan Hansen, Johanna A. Jörgensen, Jun Wu, Felix M. Mottaghy, Patrick Schrauwen, Wouter D. van Marken Lichtenbelt
Abstract
Brown adipose tissue (BAT) burns fat to produce heat when the body is exposed to cold and plays a role in energy metabolism. Using fluorodeoxyglucose-positron emission tomography and computed tomography, we previously reported that BAT decreases with age and thereby accelerates age-related accumulation of body fat in humans. Thus, the recruitment of BAT may be effective for body fat reduction. In this study, we examined the effects of repeated stimulation by cold and capsinoids (nonpungent capsaicin analogs) in healthy human subjects with low BAT activity. Acute cold exposure at 19°C for 2 hours increased energy expenditure (EE). Cold-induced increments of EE (CIT) strongly correlated with BAT activity independently of age and fat-free mass. Daily 2-hour cold exposure at 17°C for 6 weeks resulted in a parallel increase in BAT activity and CIT and a concomitant decrease in body fat mass. Changes in BAT activity and body fat mass were negatively correlated. Similarly, daily ingestion of capsinoids for 6 weeks increased CIT. These results demonstrate that human BAT can be recruited even in individuals with decreased BAT activity, thereby contributing to body fat reduction.
Authors
Takeshi Yoneshiro, Sayuri Aita, Mami Matsushita, Takashi Kayahara, Toshimitsu Kameya, Yuko Kawai, Toshihiko Iwanaga, Masayuki Saito
Copyright © 2023 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)