thermogenic

Thermogenic refers to anything that produces heat or raises energy expenditure. In biology, thermogenesis is a physiological process that maintains body temperature and contributes to basal metabolic rate. It occurs via non-shivering thermogenesis in brown and beige fat, and via shivering thermogenesis in skeletal muscle. The thermic effect of food also increases heat production after eating.

Brown adipose tissue uses the mitochondrial protein thermogenin, or uncoupling protein 1 (UCP1), to uncouple oxidative phosphorylation from ATP production, releasing energy as heat. Cold exposure and certain hormones and neurotransmitters stimulate BAT and beige fat activity, particularly norepinephrine/epinephrine and thyroid hormones.

Thermogenic capacity is highest in infants, who rely on brown fat for warmth; in adults, BAT is present but typically less abundant and variable between individuals. Environmental temperature, diet, exercise, and genetics influence thermogenesis.

Dietary or pharmacological agents marketed as thermogenic include caffeine, capsaicin (chili peppers), catechins from green tea, and other plant compounds; these may modestly raise energy expenditure. Some drugs with thermogenic effects have been associated with cardiovascular risks and are subject to regulation; many jurisdictions ban or restrict stimulants marketed for weight loss.

Applications and research: Thermogenesis is studied for obesity and metabolic health, including attempts to activate BAT or convert white fat to beige fat. Measurement methods include indirect calorimetry and imaging of BAT activity. While thermogenesis contributes to energy expenditure, its role in long-term weight loss is complex and influenced by compensatory mechanisms.