Adaptive Thermogenesis

Adaptive thermogenesis is a regulated change in energy expenditure that occurs in response to changes in energy balance. In body-weight research, the term commonly refers to a change in energy expenditure that differs from what would be predicted from changes in body mass and body composition alone. It can affect resting as well as non-resting components of energy expenditure .^1,2

During sustained energy restriction and weight loss, energy expenditure normally falls partly because a smaller body requires less energy to maintain and move. Adaptive thermogenesis refers specifically to an additional reduction beyond these expected effects. This energy-sparing response can reduce the size of the energy deficit created by reduced food intake. Changes in energy expenditure can also occur during overfeeding, although their magnitude and components can differ from those observed during weight loss .¹

Adaptive thermogenesis is influenced by physiological changes accompanying altered energy availability and body weight, including changes in hormonal and nervous-system signals. It should therefore be distinguished from changes in energy expenditure that are expected solely from changes in body mass and composition .¹

The size and persistence of weight-loss-associated adaptive thermogenesis vary among individuals and studies. A systematic review found evidence for it in many weight-loss studies but also found that estimates tended to be smaller or nonsignificant in studies using stronger methods and that the effect may diminish after a period of weight stabilization. Adaptive thermogenesis is therefore a measurable physiological phenomenon, but not a fixed metabolic response of the same magnitude in everyone .²