Physical activity associated with fidgeting, restlessness, stretching, maintenance of posture, moving around and other activities of daily life. In a Mayo Clinic study in which 16 people volunteered to stuff themselves with 1,000 extra calories a day for eight weeks, some gained as much as 16 pounds, while others gained as little as two pounds. The difference, according to the researchers, was due to increased total daily energy expenditure through increased NEAT. Those people who had the greatest increase in NEAT gained the least fat, and those who had the least change gained the most. These results suggest that as humans overeat, activation of NEAT dissipates excess energy to preserve leanness and that failure to activate NEAT may result in ready fat gain.
In a later study Levine et al. examined NEAT’s role in obesity by measuring volunteers’ body postures and movements every half-second for 10 days. Obese individuals were seated, on average, two 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, the authors concluded, 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.