Energy expenditure of nonexercise activity

Background: We found recently that changes in nonexercise activity thermogenesis (NEAT) mediate resistance to weight gain with overfeeding in sedentary adults. A potentially important, yet seldom investigated, component of NEAT is the energy expenditure of fidgeting-like activities. Objective: Our goal was to measure changes in energy expenditure with fidgeting-like activities. Design: Energy expenditure was measured in 24 subjects (17 women and 7 men; x̄ ± SD body weight: 76 ± 21 kg) while recumbent at rest, sitting motionless, standing motionless, partaking of self-selected fidgeting-like movements while seated and while standing, and walking on a treadmill at 1.6, 3.2, and 4.8 km/h (1, 2, and 3 mph). Measurements were performed by using a high-precision, indirect calorimeter connected to the subject via a transparent, lightweight facemask that enabled almost unrestricted movement. Results: Compared with metabolic rate in the supine position (5.4 ± 1.5 kJ/min), energy expenditure increased while sitting motionless by 4 ± 6%, while fidgeting while seated by 54 ± 29% (P < 0.0001), while standing motionless by 13 ± 8% (P < 0.0001), while fidgeting while standing by 94 ± 38% (P < 0.0001), while walking at 1.6 km/h by 154 ± 38% (P < 0.0001), while walking at 3.2 km/h by 202 ± 45% (P < 0.0001), and while walking at 4.8 km/h by 292 ± 81% (P < 0.0001). There was a significant, positive correlation between changes in energy expenditure and body weight for fidgeting-like activities while standing (r = 0.43, P = 0.02) but not while seated. Conclusions: There is marked variance between subjects in the energy expenditure associated with self-selected fidgeting-like activities. The thermogenic potential of fidgeting-like and lowgrade activities is sufficiently great to substantively contribute to energy balance.