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natmackow's picture

Set points determined by the NS, I-function and hormones

I found our discussion of set points in body temperature and weight to be intriguing. The idea that body weight is controlled by a negative feedback loop that opposes weight changes (bringing it back up or down to a set point) makes sense as far as how difficult it is for diets to actually work. In many cases people want to lose weight through dieting and they can, for a time. However, it seems that the i-function does not have as much control over this and that the nervous system ultimately brings body weight to a point where it feels the individual is stable, so to speak. As this set point changes when women are pregnant, I think it would make sense that the NS would alter the set point when individuals make healthy or unhealthy long-term lifestyle changes. For instance, I would expect the body weight set point to change for an individual who used to exercise once or twice a week and ate McDonalds frequently and who now goes on morning walks and eats frequent balanced meals.

Another interesting phenomena I’ve thought about involves individuals with hyperthyroidism who seem to lose weight despite the fact that they have not changed their daily routine or the foods they consume. In these individuals it seems that an outside force (from the NS/I-function), the thyroid, determines the set points for an individual’s weight, body temperature, and perhaps the balance of chemicals in the brain related to anxiety and restlessness. Irregularities in the ways these hormone-producing entities work seem to override the I-function and the NS in creating and maintaining a set point (hormone changes are also involved in the weight changes in pregnant women as well). Perhaps there are additional contributors to the maintenance of such set points? Or perhaps the thyroid and other hormone producing entities in the body can be considered a part of the nervous system?
 

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