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Nutritionist Advice

What Does it Mean to be Insulin Resistant?

Answers to your questions about prediabetes and diabetes.

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Q: My doctor told me that I have “insulin resistance,” and that I may be headed for diabetes. What is insulin resistance, and what can I do about it?

A: The cells of your body need sugar for energy. The sugar they need is glucose, which powers your brain, muscles, and other parts of your body, just as gasoline powers a car. To get glucose into your cells, your body makes insulin, a hormone that acts like a key. It attaches to the surface of your cells, allowing glucose to enter. For some people, the cells do not respond well to insulin. Imagine that you try to start your car and insert your key into the ignition, only to find that it does not turn very easily. Looking more closely, you discover that some mischievous person put gum in your ignition. There is nothing wrong with your key, but your ignition does not work right.

This is essentially what happens in insulin resistance: The insulin “key” attaches to the surface of the cells normally, but the cells don’t respond as they should. That’s where the problems start. If glucose cannot get into your cells, it builds up in your bloodstream. Your body responds by producing more and more insulin, eventually getting at least some glucose in the cells where it belongs. But as the years go by, your body may not be able to produce enough insulin to overcome the cells’ resistance. At that point, your cells cannot get the glucose they need. And you’ll find yourself low on energy, like a car that’s run out of gas. Meanwhile, the glucose that builds up in your blood can harm the blood vessels in your eyes, kidneys, and heart. This condition is called type 2 diabetes, and it has reached epidemic proportions in North America and much of the rest of the world.

Q: What causes it?

A: Insulin resistance is partly genetic. But there are other important contributors. One of the most important was found by researchers using special scanning techniques. Looking into the cells of people with insulin resistance, they found tiny particles of fat. These fat particles are especially common in muscle cells. Like gum in a lock, a buildup of fat particles in cells interferes with insulin’s ability to open the cell membrane and allow glucose inside. Researchers at Yale University scanned the muscle cells of young adults whose parents or grandparents had diabetes. Even though these young people were slim and healthy, many had microscopic fat particles already building up in their muscle cells, suggesting that they were headed for diabetes. These fat particles are the result of diets loaded with fatty foods, along with sugar and overly refined carbohydrates that pack in more calories than we need.

Q: Does insulin resistance cause other problems too?

A: Yes. It also contributes to polycystic ovary syndrome (PCOS). In this condition, women lose their normal ovulation cycle, which can lead to infertility. The problem is that increased insulin produced in response to insulin resistance ends up triggering changes in sex hormones, especially an increase in testosterone in a woman’s bloodstream. Symptoms of PCOS include irregular periods, weight gain, acne, and an increase in facial hair. As you can imagine, women with PCOS are at risk for developing type 2 diabetes.

Q: So if sugar is building up in the bloodstream, does that mean I should avoid carbohydrates, such as bread or rice?

A: Just the opposite. You would do better to have more healthful carbohydrates and a lot less fat. Here’s why: In Asian countries, where meals have long been centered on rice, insulin resistance and diabetes were relatively rare—until fast-food restaurants arrived. As Asian diets have Westernized over the past few decades, with increasing amounts of meat, cheese, fried foods, and sugar, diabetes rates have exploded. Remember those fat particles in your cells? Well, fatty foods can cause them to build up remarkably quickly. In a study, researchers in Baton Rouge, La., fed high-fat meals to 10 young men. After just three days, the fat particles in the men’s cells had built up significantly. Meanwhile, a team of London researchers tested people who were following vegan diets, finding that they had significantly less fat in their muscles compared to other people. So getting the fatty foods off your plate is a good way to “clean out” your cells, so to speak, and a good way to tackle insulin resistance. The most powerful diets set animal products aside, keep vegetable oils low, and emphasize natural foods—beans, whole grains, vegetables, and fruits. Physicians Committee for Responsible Medicine studies have shown that these foods can reduce insulin resistance, promote weight loss, and dramatically improve diabetes.