Non-exercise activity thermogenesis is the energy expended from everything we do that is not sleeping, eating or exercise.
Because calories are burned not just in the gym but through ‘all the activities we undertake as vibrant, independent beings’:
NEAT includes the energy expenditure of occupation, leisure, sitting, standing, walking, talking, toe-tapping, playing guitar, dancing, and shopping… NEAT is therefore the most variable component of energy expenditure, both within and between subjects, ranging from ∼15% of total daily energy expenditure in very sedentary individuals to 50% or more of total daily energy expenditure in highly active individuals.
The potential variance in NEAT is therefore substantial and can vary for a given person by as much as 2000 kcal per day.
NEAT and weight loss
A number of studies have linked changes in NEAT to weight gain/loss:
In one study, 12 pairs of twins were overfed by 1000 kcal per day. There was 4-fold variation in weight gain, which by definition must have reflected substantial variance in energy expenditure. Because the changes in energy expenditure were not accounted for by changes in basal metabolic rate, indirectly changes in NEAT were implicated.
And obesity has been associated with a genetic bias to sit down:
Obese individuals appear to exhibit an innate tendency to be seated for 2.5 hours per day more than sedentary lean counterparts. If obese individuals were to adopt the lean “NEAT-o-type,” they could potentially expend an additional 350 kcal per day. Obesity was rare a century ago and the human genotype has not changed over that time. Thus, the obesity epidemic may reflect the emergence of a chair-enticing environment to which those with an innate tendency to sit, did so, and became obese.