Monday, December 6, 2010

What Is Insulin Resistance?

A reader asks us, "Can you explain in plain language what is insulin resistance? And what are insulin resistance symptoms?"

There are two ways of looking at the problem of insulin resistance. The older way of understanding how it worked was the idea that somehow when blood sugar levels got too high, they coated the linings of the tiny blood vessels that carry blood deep inside the muscles and vital organs. Sugar in the bloodstream couldn't smash through the caramel-coating of the capillaries and insulin could not carry it where it needed to go. Nowadays scientists know that capillaries do not get literally sticky, although there are other factors, such as inflammation, that cause the same effect.

The modern way of looking at insulin resistance is to consider it a cellular level. If lots and lots of sugar found its way inside a cell, it would "flame out" in hyperactivity. (Actually, in certain kinds of cells that do not have the ability to resist insulin, such as the ovaries, this is more or less what happens.) The cell then "turns off" insulin receptors so sugar won't flood in. This process is known as insulin resistance.

There are complicated tests for insulin resistance, but one of the most reliable insulin resistance symptoms is weight gain. When cells turn off their receptors for insulin for transporting sugar, they don't turn off their receptors for insulin for transporting fat. The pancreas makes more and more insulin to try to get blood sugar levels back down to normal. In prediabetes, this works, but at the expense of storing any excess fat. Insulin resistance does not guarantee that you will gain weight. You still have to eat too much for that to happen. But insulin resistance makes it very likely you will gain weight whenever you eat too much.

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