Ageing and Nutrition (part 3) – it’s all about Insulin

To really understand the rationale and physiology of keto adaptation I will give a brief overview of the chemistry of Insulin.  I personally believe this is the villain of modern day obesity and metabolic syndrome where Insulin Resistance and hyperinsulinemia are the rule.

Insulin is a polypeptide hormone that promotes glucose utilization, protein synthesis and the formation and storage of lipids. Produced by specialised endocrine cells of the pancreas called the islets of Langerhans, insulin was discovered in 1921 by two Canadian researchers, Dr Frederick Banting and his medical assistant Charles Best.

Insulin is crucial to the transport of glucose and amino acids into muscle cells. Properly managed by the right diet, insulin is the athlete’s best friend as it plays an enormous role in muscle hypertrophy (growth). With the support of human growth hormone (hGH), it has a direct effect on the production of somatomedins in the liver. Somatomedins are called insulin like growth factors or more commonly IGF. For this reason insulin has earned the reputation of an anabolic hormone.

However, insulin is a double-edged sword. It is also the hormone of feasting and plenty and depending on what is eaten and when, insulin functions as a brilliant fat storage hormone.

Our ability to respond to insulin is called insulin tolerance. The more tolerance a person has for insulin, the more insulin it takes to get a response (this is Insulin resistance). A low tolerance to insulin is preferable, as excessive insulin production is associated with obesity, high cholesterol, high triglycerides, hypertension, vascular disease, fatigue and adult-onset type II diabetes. Many overweight individuals have excess insulin in their blood due to excessive stimulation of the pancreas. This condition is called hyperinsulinemia.

The hallmark of the metabolic Syndrome is resistance to insulin, which many experts claim is caused by eating too many processed high-carbohydrate foods. This common dietary practice, where carbohydrates generally make up 65% of daily calories, in turn causes an excess build-up of glucose in the blood resulting in the production of free-radicals and advanced glycaemic end products (AGEs) by couple glucose the protein molecules.  AGEs causes the proteins to malfunction and is thought to be key in the pathology driving unhealthy ageing.

Metabolic Syndrome was coined in 1988 by Dr. Gerald Reaven, a Stanford University endocrinologist, and defined by a cluster of related symptoms that always includes insulin resistance and one or more of the following conditions; abnormal blood fats, elevated uric acid, reduced HDL, increased oxidized LDL particles, overweight and high blood pressure.

Insulin resistance involves the release by the pancreas of more insulin than the target cells in the body can handle. Excess carbohydrate intake in the form of sugar, bread, potatoes, pasta, bagels, chips, cookies, breakfast cereals, etc cause blood glucose levels to rise excessively, and in response, the pancreas releases more and more insulin. Eventually, the cell receptors of muscle and vital organs become saturated, non-responsive and may even shut down. Then, glucose and insulin begin to accumulate to toxic levels in the bloodstream, becoming agents of hostility and damage. Clotting factors are activated and advanced glycation end products (AGEs) begin to form. It is estimated that as many as 40% of North American adults have this syndrome.

Sleep deprivation depresses growth hormone release, slows muscle and strength gains and negatively influences immune function. Insomnia and sleep deprivation also cause insulin resistance, which promotes intra-abdominal obesity. This translates to that dreaded spare tire around the gut, which happens to be the most dangerous region to store excess bodyfat in terms of disease risk for the body, especially heart disease.

Ideally, we don’t want to constantly flood the body with high-glycemic, low fiber, low water volume carbohydrates such as sugar and white flour, as this causes insulin to spike. It’s much better to consume minimal carbohydrates that are metabolized slowly and that release their sugars over a longer period of time.

Consuming low-glycemic carbs in smaller portions keeps glucose and insulin closer to a normal fasting baseline for a good anabolic effect, not too high or too low.

Another problem with high Insulin is suppression of testosterone levels, adding to impaired muscle strength and performance and sexual dysfunction.

Nutrients that optimize insulin activity, improve its sensitivity and protect it and the pancreas from oxidative damage include B6, niacin, magnesium, chromium, vanadium, alpha-lipoic acid, vitamin C and the omega-3 fatty acids, including alpha-linolenic acid and eicosapentanoic acid (EPA) and decosahexanoic acid (DHA).

Insulin has a direct effect on the metabolism and storage of fat. For instance, insulin accelerates the transport of glucose from the blood into cells and the conversion of glucose into fatty acids. This is called lipogenesis. Insulin has a greater half-life than glucose, so any insulin left circulating in the blood after it has completed its work is also converted into fat. And the effect is even more reliable if by genetic predisposition you have a slow metabolic rate and spend most of your free or work time seated.

If levels of insulin climb too high, which can happen simply by eating a large meal or a meal dominated by carbohydrates such as bread, rice or pasta, a simultaneous increase in the enzymes lipoprotein lipase and acetyl-CoA carboxylase occurs. Both of these enzymes facilitate the transport of fatty acids into fat cells. High insulin levels activate lipoprotein lipase and increase its activity. Lipoprotein lipase promotes the removal of triglycerides from the bloodstream and encourages their deposition in adipocytes or fat cells. Insulin also inhibits the action of hormone-sensitive lipase which breaks down stored fats for use as energy. So anytime you catch yourself eyeing a muffin or a slice of bread, focus for a moment in advance of the indulgence. Think of what effect it will have on your blood chemistry and body composition. Remember, insulin inhibits the mobilisation of stored fat and promotes fat deposition add to the visceral adiposity.

If insulin levels are continuously sustained above baseline throughout the day, enzymes like lipoprotein lipase can suppress the oxidation of fatty acids, even while consuming a negative calorie intake combined with exercise. This is called an anti-lipolytic (anti-fat beakdown) effect where your fat stores are preserved even though total calorie intake may be quite low. While the caloric profile of food is a factor in weight management, the chemistry of food is more important to understand. The irony of this is that few people really get this concept or even think about it.



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