Tuesday, October 25, 2011

Insulin Resistance

 Why are so many of us overweight, and what links does obesity have to diabetes and other major disease of our time, like heart disease and cancer? Even the "experts" agree that these diseases are all linked - its called the "Metabolic Syndrome," and that insulin plays a major role.

The part that is unclear to most nutritionist and doctors is the cause and effect. Most health care professionals believe that obesity is caused by simply eating too many calories and that its the obesity itself that causes insulin problems in the body. I believe they have it backwards.

Insulin is a hormone in the body that plays many roles. Its primary job is to enable us to use glucose as fuel for our cells. It is, in fact, the only hormone that causes fat to be stored. We have insulin receptors on our cells - all cells. Heart, liver, adipose (fat), muscle, and brain all have insulin receptors that sense the presence of glucose in our blood stream, and allow the addition of GLUT4 receptors on the cell membrane to uptake the glucose into our cells.

When the body is overwhelmed by the presence of carbohydrate, the insulin receptors begin to stop being as productive. They become resistance to the presence of glucose. (Fructose as well, which is a major cause of the problem, and I'll get to that in a little bit.) Sometimes the receptors work properly, but they are unable to signal the introduction of the GLUT4 receptors that actually absorb the glucose into the cell. Either way, the body responds by releasing additional insulin from the "islets of Langerhans" cells in the pancreas. This additional release of insulin has tragic consequences.

Frequently, the first cells to become resistance to insulin, and thus become unable to use the glucose as fuel, are the muscle cells. Usually adipose tissue is less insulin resistant. So the body responds to this additional insulin by dumping fat and protein into the fat cells. See, its not even the glucose that gets stored. Many in the field of nutrition talk about glucose as being the "preferred fuel" but that doesn't make sense, as glucose is simply empty calories. The body is poisoned by the glucose because it raised blood sugar levels, which have to be kept within strict limits - between 4-6 mM. Because the body wants to be rid of the glucose, it stores the fat and protein in the blood stream for energy use after the glucose is burned off. And any excess glucose is stored as well.

Fructose is even more poisonous to the body. It only exists in the wild in very small amounts in fruit. Most fruit grows in the summer, or in tropical climates, when there is ample sunlight available to also produce large amount of vitamin D in the body. Vitamin D plays a big role in the digestions of carbohydrates and the release of insulin, although this relationship is not well understood. Fructose is digested exclusively by the liver, and has to be packaged into very-low-density-lipoproteins (VLDLs) to be carried through the blood stream. These VLDLs have strong links to heart disease. Also, the fructose often get stored in the liver, and has strong links to fatty liver and liver cirrhosis, also known as "non-alcoholic fatty liver disease." Fructose makes up half of the sugar molecule, as well as about half of high-fructose corn syrup (HFCS), and has never been present in the human diet in the amounts seen today. Mainly this consumption comes from soda (which I call the "cigarette of the future"). There is a growing body of evidence that the fructose itself is what causes the insulin resistance in the first place, and creates the situation where the body can't effectively digest glucose.

So how do we improve our insulin sensitivity, especially in the muscle cells? How do we get our bodies to begin to use the glucose in our blood streams as fuel, rather than storing it as fat, along with the dietary fat and protein? How do we lose weight?

There are a number of things we can do. The first and most obvious, which I have written about extensively, is to cut our carbohydrates, especially sugar and other forms of fructose like HFCS and excessive fruit. A little fruit is not the problem, but it's also not the health food it's made out to be. It's meant to be eaten in the fall at harvest time, in order to store fat for winter, or eaten in tropical climates with 8 hours a day of sunlight on the skin.

In addition to vitamin D (which is needed in much larger amounts in places like Minnesota -I take 10,000 IUs a day), the other less obvious solutions include supplements of magnesium and fish oil. The long chain fatty acids in fish oil improve our cell membrane structure, and allow the body to heal from insulin resistance.

And most importantly, we can engage in a type of exercise called "interval training". This includes small periods of high heartrate-inducing exercise, followed by periods of rest. Usually about 60 seconds on, and then 75 seconds off. This is more effective than long periods of cardio, which is suspected to be hard on the heart and nervous system. It's not so much the "calories" burned by the exercise, as it is the increased insulin receptors that the exercise creates on the muscle cells. When we have additional insulin receptors on our muscle cells, our body is able to use the (small) amount of glucose that we consume as fuel, rather than only storing it and the food we eat with it, as fat.

This not only enables us to continue to safely eat a little carbohydrate, but it helps us lose weight and improves our resistance against metabolic diseases, which are the number one killer in our society!