Brown adipose tissue (BAT) burns fat to produce heat in response to cold and plays a key role in energy metabolism. This study investigated the effects of repeated cold exposure and capsinoids (nonpungent capsaicin analogs) on BAT activity and body fat in healthy humans with low BAT activity. Cold exposure at 19°C for 2 hours increased energy expenditure (EE), and cold-induced thermogenesis (CIT) was strongly correlated with BAT activity. Daily cold exposure at 17°C for 6 weeks increased BAT activity and CIT, while decreasing body fat mass. Similarly, daily capsinoid ingestion for 6 weeks increased CIT. These results suggest that BAT can be recruited even in individuals with low BAT activity, contributing to body fat reduction. BAT is a site of nonshivering thermogenesis and has potential as an antiobesity agent. Previous studies using FDG-PET/CT showed that BAT activity decreases with age and is inversely related to body fat content. Cold exposure is a powerful stimulus for BAT activation, and capsinoids, which activate TRP channels, also enhance BAT thermogenesis. The study found that chronic cold exposure and capsinoid ingestion can recruit BAT in humans, leading to increased energy expenditure and reduced body fat. The study involved 51 healthy male subjects and 22 subjects with low or undetectable BAT activity. Cold exposure at 17°C for 2 hours daily for 6 weeks increased BAT activity and CIT, while capsinoid ingestion also increased CIT. BAT activity was closely related to CIT, and increased BAT activity was associated with reduced body fat mass. These findings suggest that BAT recruitment through cold exposure or capsinoids can be an effective strategy for body fat reduction in humans. The study also indicates that BAT recruited by cold and capsinoids is likely composed of beige cells. The results demonstrate that human BAT can be effectively recruited to reduce body fat, offering a potential approach for antiobesity therapy.Brown adipose tissue (BAT) burns fat to produce heat in response to cold and plays a key role in energy metabolism. This study investigated the effects of repeated cold exposure and capsinoids (nonpungent capsaicin analogs) on BAT activity and body fat in healthy humans with low BAT activity. Cold exposure at 19°C for 2 hours increased energy expenditure (EE), and cold-induced thermogenesis (CIT) was strongly correlated with BAT activity. Daily cold exposure at 17°C for 6 weeks increased BAT activity and CIT, while decreasing body fat mass. Similarly, daily capsinoid ingestion for 6 weeks increased CIT. These results suggest that BAT can be recruited even in individuals with low BAT activity, contributing to body fat reduction. BAT is a site of nonshivering thermogenesis and has potential as an antiobesity agent. Previous studies using FDG-PET/CT showed that BAT activity decreases with age and is inversely related to body fat content. Cold exposure is a powerful stimulus for BAT activation, and capsinoids, which activate TRP channels, also enhance BAT thermogenesis. The study found that chronic cold exposure and capsinoid ingestion can recruit BAT in humans, leading to increased energy expenditure and reduced body fat. The study involved 51 healthy male subjects and 22 subjects with low or undetectable BAT activity. Cold exposure at 17°C for 2 hours daily for 6 weeks increased BAT activity and CIT, while capsinoid ingestion also increased CIT. BAT activity was closely related to CIT, and increased BAT activity was associated with reduced body fat mass. These findings suggest that BAT recruitment through cold exposure or capsinoids can be an effective strategy for body fat reduction in humans. The study also indicates that BAT recruited by cold and capsinoids is likely composed of beige cells. The results demonstrate that human BAT can be effectively recruited to reduce body fat, offering a potential approach for antiobesity therapy.