«[...] The BMI (body mass index) of adopted children usually correlates nicely with that of their biological parents, but not with that of their adoptive parents. This strongly suggests that genetics, not "psychology", play the larger role in human obesity. Leibel began a painstaking search for the elusive satiety factor in the adipose tissue of normal mice.
Generally, scientists agree that metabolic rate is a very poor predictor of obesity, but what is almost certainly a potent factor is "non-exercise activity thermogenesis", or Neat. Neat is what most of us think of as nervous energy - the fidgeting, restless pacing, maintenance of posture and other subliminal activities of daily life. For reasons not yet understood, some people sharply increase these unconscious exertions in response to overeating. James Levine, an endocrinologist at the Mayo Clinic in Minnesota, conducted a study in which 16 volunteers (including Levine himself) were overfed 1,000 calories a day for two months. On average, the volunteers gained 10lbs. But, as is often the case, the average was not particularly revealing. One subject gained only 2lbs, while another gained 16lbs. Levine sorted through a range of factors and concluded that differences in Neat levels accounted for a tenfold difference in fat storage among the volunteers.[...]»