Energy expenditure of nonexercise activity

Background: We found recently that changes in nonexercise activity thermoge nesis (NEAT) mediate resistance to weight gain with overfeeding in sedentar y adults. A potentially important, yet seldom investigated, component of NE AT is the energy expenditure of fidgeting-like activities. Objective: Our goal was to measure changes in energy expenditure with fidge ting-like activities. Design: Energy expenditure was measured in 24 subjects (17 women and 7 men; (x) over bar + SD body weight: 76 +/- 21 kg) while recumbent at rest, sitt ing motionless, standing motionless, partaking of self-selected fidgeting-l ike movements while seated and while standing, and walking on a treadmill a t 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 movemen t. Results: Compared with metabolic rate in the supine position (5.4 +/- 1.5 W /min), energy expenditure increased while sitting motionless by 4 +/- t6%, while fidgeting while seated by 54 +/- 29% (P < 0.0001), while standing mot ionless 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), w hile 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 cor relation between changes in energy expenditure and body weight for fidgetin g-Iike activities while standing (r = 0.43, P = 0.02) but not while seated. Conclusions: There is marked variance between subjects in the energy expend iture associated with self-selected fidgeting-like activities. The thermoge nic potential of fidgeting-like and low-grade activities is sufficiently gr eat to substantively contribute to energy balance.