Compensatory Responses to Exercise Training As Barriers to Weight Loss: Changes in Energy Intake and Non-exercise...

Exercise can increase total energy expenditure to very high levels and therefore induce sizable energy deficits that, under carefully controlled conditions, elicit clinically significant weight loss. In real life, however, this is seldom the case among people with overweight or obesity, suggesting the existence of compensatory mechanisms that mitigate exercise-induced negative energy balance. Most studies have focused on possible compensatory changes in energy intake, and comparably little attention has been paid to compensatory changes in the physical activity patterns outside of the prescribed exercise, i.e., non-exercise physical activity (NEPA). The purpose of this paper is to review studies that have assessed changes in NEPA in response to an increase in exercise-induced energy expenditure.

The available studies examining changes in NEPA in response to exercise training are methodologically heterogeneous, conducted in participants with different age, gender, and body adiposity, and examined responses to varying exercise regimens over a varying duration. About 67% of all studies-80% of short-term (≤ 11 wks, n = 5) and 63% of long-term (> 3 months, n = 19) studies-demonstrate a compensatory decrease in NEPA upon starting a structured exercise training program. A compensatory decrease in other physical activities of daily life upon starting exercise training is a relatively common compensatory response-and probably more common than an increase in energy intake-that may be instrumental in attenuating the energy deficit caused by exercise, and thus preventing weight loss.