Hypoglycemic conditions with regard to the brain

To Kink:

You are right to a small extent. Anorexic people and people who starve themselves to lose weight to maintain their figure (i.e supermodels) may damage the brain, regardless whether it is white or gray matter which is degenerated.

When the body is under nourished, it has a lack of carbohydrates and thus has a low source of glucose. When this happens, cells, tissues and organs in the body feed back to the brain that more glucose is needed. The brain itself also runs only on pure glucose and thus also determines more glucose is needed. However, there is no source of glucose found in the body from carbohydrates and thus other methods must be employed quickly to obtain glucose to prevent the body from suffering a neurogenic shock.

An important process to note is the process of gluconeogenesis. Gluconeogenesis refers to the production of glucose by the liver from other substances beside carbohydrates, thus referring to proteins and fats.

Muscle tissue and triglycerides (fats) are broken down to obtain glucose. Triglycerides are broken down into glycerol through lipolysis. Non-esterified fatty acids mix with the glycerol to form glucose and toxic ketone bodies. These ketone bodies, produced in the process of ketoacidosis, are toxic to the body and can lead to major organ failure.

The proteins in muscles are broken down through proteolysis to form pyruvate. Glycogen stored in the muscles is also broken down through glycogenolysis to form lactate. Together with alanine absorbed assimilation, lactate, pyruvate and alanine combine to form glucose. Thus we can see, glucose can be obtained from muscle and fat cells, however detrimental it might be.

Muscle and fat cells all over the body may be broken down for this purpose. However, the muscles and fat cells broken down are mostly cells which do not constitute any major organ in the body. It would be dangerous and suicidal if the body breaks down the proteins making up the heart just to supply glucose to the brain. In extreme cases of hypoglycemia (low blood glucose level), the brain would then be forced to shut down organs of the body, beginning with the least important. The brain’s fatty deposits may also be broken down. (N.B Brain is composed of 66% triglycerides). When the body cannot overcome the lack of glucose, it will fall into neurogenic shock, triggering sudden hypotension and stopping all organ activity.

Thus, in my opinion, it is likely that the person may suffer from ketone poisoning and muscle degeneration, but very unlikely that the brain would degenerate with starvation.