Putting behavior back into feeding behavior: a tribute to George Collier.

In an attempt to explain my failure to find any correlation between meal size and intermeal intervals in free-feeding rats, George Collier, my mentor, suggested that perhaps eating behavior had strong extra-physiological determinants, a heretical idea that had an enormous impact on my subsequent research. After moving to Cornell University, my students and I began a series of studies, first with animals, then with humans, all of which supported George's idea. We observed that, under our test conditions, humans (a) do not respond to overfeeding by reducing their food intake, (b) do not change the amount they consume at meals when snacks or breakfasts are added or subtracted from their daily intake, (c) do not change the amount they eat when the energy density of their food is changed, (d) nor do they increase their intake following a semi or total fast for 24 h. They also increase the amount they consume proportionally to the amount of food they are served, the variety of foods offered, and the number of people with whom they eat. The combination of these data with George's insightful idea, has merged into a modification of the popular Set-Point Theory of the regulation of body weight. The alternative "Settling Zone" Theory suggests that whereas biology may determine a range of body weights (adiposity) that are maintained fairly constant for long periods of time, within this "zone", the behaviors responsible for controlling energy intake and energy expenditure are influenced primarily by environmental and cognitive stimuli. The size of the "Settling Zone" is not currently known, but if it is 10% or greater, then efforts to identify and understand the environmental and cognitive stimuli that influence body weight may produce advances that will reduce our high rates of overweight and obesity. Copyright 2002 Elsevier Science Ltd.