Osteoporosis

So now that we examined Dr. Lustig's insulin theory of metabolic control we need to take a look at the reward tracts that are located in the human brain. These tracts have been well studied and their neurochemistry is well understood. What appears not to be as well known is how the hypocretin neurons and the leptin receptor control and modulate their activity. The key point here is that the dopaminegic tracts eloquently spoken of Dr. Guyenet's reward series are the "efferent only" path that is part of the effector arm of the leptin receptor and the hypocretin neurons. This means, in English, they are playing second fiddle to the leptin receptors and are not the dominant cause of obesity. They clearly play a major role in the neuro-circutry but they do not control obesity. They carry out the action but the orders were given by someone else. One of the reasons I had a major problem with the reward series, is because of my "day job" as a neurosurgeon. I have had the opportunity to operate on many brain tumors in the reward tracts and never have I ever seen either preoperatively or postoperatively one patient develop severe morbid obesity. If these tracts were truly dominant causes this would lead neurosurgeon and neurologists to see many patients with this problem. Well, we do not. That was a big issue for me with the theory. The second issue I had with it was that when we neurosurgeon's have patients with brain tumors involving the hypothalamus we see tremendous effects on feeding, obesity and on anorexia. This is well documented and I have personally seen this in many cases. Dr. Lustig pointed this out in his AHS 2011 talk when he showed some clinical cases of craniopharyngioma's and of hypothalamic trauma's that resulted in morbid obesity.