Tuesday, October 18, 2011

Sugar, Insulin Resistance

By Jason Seib

Carbohydrate is converted to glucose (blood sugar), so each one of these meals causes a nice bolus of glucose to enter your blood stream very quickly. Your body closely regulates glucose to keep it within a safe range – not too high and not too low. After you consume easily digestible carbohydrates like the ones on your daily menu above, your pancreas must secrete insulin to mitigate the resulting elevated glucose. Insulin’s job is primarily to feed the glucose in your blood stream to hungry cells and then send the leftovers to the liver to be turned into triglycerides for storage in your fat cells. Are you still with me? Take a deep breath. Maybe do a few squats. Okay, let’s keep moving. We need to dig deeper.

The story so far: carbs are eaten and broken down to glucose, insulin sends glucose to your cells to be used as energy or to the liver for a quick composition change so it can be stored as fat.

Moving on. Since your Standard American Diet (SAD) is nowhere near natural because of all those processed carbs, glucose and insulin remain high throughout your day. This can eventually lead to insulin resistance in those cells that use glucose as energy. Insulin resistance is when insulin is ever present and its “I come bearing food” signal to the cells is reduced to a whisper and then finally ignored. This means your pancreas must produce more insulin to get the same job done, and this in turn means that insulin is ever present in greater quantities. If you have managed to make sense of all this so far, you can see that you are amassing more and more insulin in your blood stream. I’m about to explain why this is a problem, but you might want to do a few more squats first.

Hyperinsulinemia, this state of elevated insulin you have created by this point, is bad. Very bad. Robb Wolf once suggested that you can Google hyperinsulinemia and any noninfectious disease that comes to mind and you will at least find strong correlations in more links than you would ever take the time to read. When insulin hangs around too often, it also means you store a lot of fat and have trouble using fat as energy. This is because insulin is your body’s primary storage hormone. Here’s how it works (take another deep breath):

High levels of glucose in the blood stream are toxic, just ask a type 1 diabetic. As I said above, your body devotes a lot of energy to keeping glucose within a fairly tight range. This means glucose is used for energy before fatty acids because it can’t be allowed to hang out and cause problems. You can only store a small amount of glucose (as glycogen), but a nearly unlimited amount of fat can be stored, much to the dismay of your buns and thighs. This is why the liver converts the extra glucose to triglycerides and ships it off to be stored in the fat cells.

Okay, we have finally come to the point of this whole sermon. At the fat cell, an enzyme called lipoprotein lipase (LPL) acts as the doorman, ushering fatty acids into the fat cells. Inside the fat cell, another enzyme, hormone sensitive lipase (HSL), has the job of cleaving the first sulfide bond on the triglycerides and releasing fatty acids to be used as energy. So LPL is working when you are storing fat and HSL is working when you are “burning” fat. Here’s the rub – both of these enzymes are sensitive to the presence of insulin. When insulin is present, LPL is on duty and you are storing fat. When insulin is gone, HSL is on duty and you are using your stored fat as energy. If you understand the story so far, this process makes perfect sense. Since we know that glucose can’t be allowed to hang out and it must be used first, we also know that there is no reason to access stored fat in the presence of glucose and, therefore, insulin. When insulin is in the blood stream, the message is clear – you have glucose to take care of before you use your stored fat. Now it’s easy to see why hyperinsulinemia and insulin resistance are a problem. They keep you in fat storage mode, without the ability to access your stored fat for energy, for plenty of time to make you plump and squishy.

Please don’t misunderstand, I am not trying to paint carbohydrates and insulin as villains. They are a normal and natural part of human nutrition and biochemistry. What is not normal is our mass consumption of processed carbohydrates, both in unnatural forms and in never ending supply regardless of season.

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