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Fixin' Healthcare

Saturday, November 05, 2005

The Dance of the Hormones

The ability to survive long periods without food favors a strong appetite and eating heartily when food is available. Eating carbohydrates produces elevation of blood sugar that stimulates release of insulin from the pancreas. Insulin transports glucose into the cells of muscle and liver tissues where it is used to produce chemical energy. The liver is influenced by insulin to synthesize fat and protein from glucose. Fat and protein are used to produce biochemical components, hormones and tissues. Unprocessed carbohydrates (vegetables, fruit and grains) contain lower concentrations of sugar than processed carbohydrates (crackers, chips and candy) and the presence of fiber slows the absorption of sugar from the gut. This reduces the level of blood sugar and insulin secretion.

The large human brain is important for adaptation and survival. The brain utilizes only glucose for energy and brain cells have priority since the hormone insulin is not required for glucose to cross the cell membrane. Muscle and liver cells can utilize fat and protein as well as glucose for energy, and insulin is required for glucose to pass the cell membrane. Survival in an environment with low carbohydrate but adequate protein and fat favors selection for insulin resistance in order to conserve glucose for the brain. These were the conditions of the Ice Age. However, insulin resistence in a carbohydrate rich environment results in metabolic syndrome and Type-2 diabetes mellitus. These are the conditions that exist today.

Most of the stored energy reserve is fat. It is the most efficient storage of energy at nine calories per gram versus four calories per gram for protein and glucose, and it serves as insulation for the body. Very little excess glucose is stored in the form of glycogen as energy reserve. Glycogen is the most ready source of energy reserve, then fat and protein serve as fuel. The utilization of reserve energy is under the influence of the hormone cortisol from the adrenal glands. The loss of body fat slows metabolism and conserves energy stores. This is an example of the protective and buffering systems that are intrinsic to metabolism.

Adrenalin and cortisol are the stress hormones. They prepare the body for physical activity by maintaining blood pressure, mobilizing glucose from the small quantities of stored glycogen and influencing the conversion of fat and protein into glucose. Mobilization of glucose in this manner provides fuel to muscle for physical activity. Chronic stress with elevation of cortisol contributes to insulin resistence that returns top priority for glucose to the brain. Starvation and very low calorie diets are examples of chronic stress that result in the body consuming fat and protein to sustain blood glucose levels for the brain.

Nutrition, physical activity and metabolism are related in a purposeful way mediated by the major hormones. Humans are adapted to be physically active for long periods with capability for brief periods of extreme intensity of effort that results in many influences upon metabolism. For example, physical activity reduces the influence of cortisol and increases insulin sensitivity. This makes glucose more available to muscle cells for physical activity. Adequate nutrition is necessary to provide fuel and the building materials to restore biochemical compounds and rebuild tissue worn down by physical activity. Excessive exercise and exercise without adequate nutrition are examples stress that result in the body consuming itself (loss of muscle).

Chronic stress associated with a high calorie, carbohydrate rich diet and physical inactivity create an abnormal state of metabolism with concurrent elevations of the stress hormones and insulin. The result is obesity with muscle wasting and fat deposition in the abdomen. Chronic elevation of cortisol has a negative impact upon immunity that contributes to development of chronic diseases.

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