A new article in Science comes to the conclusion that lean individuals differ from obese ones in the amount of time they spent standing up. For a non-technical summary see The Fit Tend to Fidget, and Biology May Be Why, a Study Says and Why fidgeters tend to be leaner.
Science, Vol 307, Issue 5709, 584-586 , 28 January 2005
Interindividual Variation in Posture Allocation: Possible Role in Human Obesity
James A. Levine et al.
Obesity occurs when energy intake exceeds energy expenditure. Humans expend energy through purposeful exercise and through changes in posture and movement that are associated with the routines of daily life [called nonexercise activity thermogenesis (NEAT)]. To examine NEAT's role in obesity, we recruited 10 lean and 10 mildly obese sedentary volunteers and measured their body postures and movements every half-second for 10 days. Obese individuals were seated, on average, 2 hours longer per day than lean individuals. Posture allocation did not change when the obese individuals lost weight or when lean individuals gained weight, suggesting that it is biologically determined. If obese individuals adopted the NEAT-enhanced behaviors of their lean counterparts, they might expend an additional 350 calories (kcal) per day.