Caffeine can potentially enhance the dopamine-mediated effects of cold exposure, which works at least in part by increasing the amount of dopamine-receptor availability in the brain. In a 2015 trial that investigated caffeine's effect on dopamine receptors, increased dopamine receptor availability was observed 60 to 120 minutes after the participants took a single 300-milligram dose of caffeine.[1] Because cold exposure actually increases dopamine levels,[2] the results of the 2015 trial suggest that taking a similar dose of caffeine 60 minutes before cold exposure could enhance some of its dopamine-related benefits.
Capsinoids such as capsaicin — the component of chili peppers that makes them hot — can both mimic and enhance cold-exposure-induced thermogenesis.[3][4] Capsaicin mimics the effects of cold exposure on thermogenesis in brown adipose tissue (BAT; a type of body fat) by activating the transient receptor potential (TRP) channels, a specialized group of ion channels that span the cell membranes and transmit information about environmental changes such as touch, temperature, and pain to the brain.[5] Capsaicin activates TRPV1, one of the TRP receptors that senses cold, which causes the brain to increase BAT activation through the sympathetic nerves connected to BAT and triggers thermogenesis in this tissue.[3][6]
The efficacy of capsaicin in increasing energy expenditure through BAT activation may depend on the presence of active BAT because participants without active BAT in one trial did not have significantly increased energy expenditures after a single dose of capsaicin.[7] However, another trial found that taking a single 9-milligram dose of a capsinoid extract for 6 weeks increased cold-induced thermogenesis in participants with low BAT activity.[8] Additionally, a study in rodents found that daily capsinoid ingestion in combination with mild cold exposure at 17°C (63°F) enhanced the beiging of white adipose tissue (WAT; another type of body fat), which prevented obesity in animals that were fed an experimental high-fat diet.[9] Although the ability of capsaicin to enhance WAT beiging in humans is uncertain, an cell-culture study published in 2022 confirmed that capsaicin induces the beiging of human white adipocytes that were derived from dermal fibroblasts (a type of skin cell) and were growing in culture.[10] Given the ability of capsaicin to induce beiging in human fat cells growing in culture, capsaicin may have the potential to enhance WAT beiging in the human body. However, randomized controlled trials specifically designed to test for this in humans are needed.