From the ubiquitous mentions, it may also seem as if every person who is overweight has insulin resistance and as if people who don’t have weight issues don’t need to worry about it. But that’s not necessarily true. Here are the facts about insulin resistance, including what it is, how to know whether you might have it, and how it can be managed.
What is insulin resistance?
Insulin is a hormone made by the pancreas. It helps the sugar (glucose) in your blood enter the cells throughout your body, where it’s turned into usable energy.
After you eat a meal or snack, the amount of glucose in your bloodstream rises. In response, your pancreas will release insulin into your bloodstream, where it will help the glucose get to the cells that need it. This brings the amount of sugar in your bloodstream back to the normal range (a fasting plasma glucose level of 100 mg/dL or less).
Insulin resistance occurs when the body doesn’t respond as well to insulin and glucose is less able to enter the cells. Imagine that the cells are a locked door, but the keyhole is rusty, so it’s difficult for glucose to get inside. The pancreas keeps pumping out more insulin to help, but glucose still has a hard time getting into the cells. This causes blood sugar levels to rise.
“When the increase in blood sugar level is mild, we call this prediabetes; the threshold is fasting glucose 100 mg/dL up to 125 mg/dL,” says Silvio Inzucchi, medical director of the Yale Diabetes Center. According to the Centers for Disease Control and Prevention, more than 1 in 3 Americans (about 88 million people) have prediabetes. If fasting glucose is higher than 126 mg/dL, a person would be diagnosed with Type 2 diabetes.
“Think of this as a continuum of abnormal glucose levels that rise higher and higher over time if no healthy lifestyle actions are taken to slow or stop this disease progression,” said Hope Warshaw, a registered dietitian and certified diabetes care and education specialist in Asheville, N.C. The abnormal glucose levels associated with diabetes can eventually damage blood vessels and endanger organs throughout the body.
But insulin resistance isn’t only related to diabetes; it has also been linked to an increased risk of cancer and heart disease, high blood pressure, a higher waist circumference, high cholesterol, inflammation, altered liver function and perhaps even dementia.
Thankfully, it can be years before insulin resistance results in prediabetes or other health conditions. “It’s a slow process,” Inzucchi says. That’s good news, because it means that you can slow down — and even reverse — insulin resistance.
Who is prone to insulin resistance?
But how do you know you have insulin resistance? After all, there are no exact symptoms and there is no “insulin resistance” test.
If you’ve been diagnosed with high triglycerides, high LDL cholesterol, or low HDL cholesterol, those are signs that you may be insulin resistant and may want to consider lifestyle changes. Other hints include a family history of Type 2 diabetes; being inactive; having poor sleep habits; eating a lot of fast food, refined sugar and flour; or a combination of these factors. There’s also a link between insulin resistance and weight.
“We know from National Health and Nutrition Examination Survey data that insulin resistance is prevalent in obese populations, but we also know that how you carry your weight matters,” says Katherine Tom, a registered dietitian and certified diabetes care and education specialist in Dallas. “Carrying excess fat tissue around the midsection puts a person at risk for insulin resistance, regardless of what their scale says.”
Having a lot of midsection fat is problematic, because it means you may have more visceral fat, a type of “active fat” around the organs that can release fatty acids, hormones and pro-inflammatory cytokines into the circulation and has been associated with insulin resistance. Researchers are still working on understanding the link between the two.
But does weight gain lead to insulin resistance, or is it the other way around? “Obesity leads to insulin resistance, with less evidence for a relationship in the other direction,” Inzucchi says. Importantly, you do not have to be obese to have insulin resistance, and not all people who are obese have insulin resistance. A recent study showed that about 40 percent of Americans ages 18 to 44 probably have insulin resistance, and nearly half of them are not obese.
Beyond weight, other factors can lead to insulin resistance, including genetics, environmental factors, eating habits, food choices, physical activity, stress, exposure to toxins and access to medical resources. Insulin resistance is also more common in African Americans, Latinos and Native Americans than in White people, which brings racial disparities into the equation, too.
How can insulin resistance be reversed?
“Several actions are known to decrease insulin resistance,” Warshaw says. Among them are weight loss, exercise, glucose-lowering medication, and changes in food choices or eating habits.
Tom says exercise is the most effective tool. Exercise helps by reducing body fat, which makes cells less resistant to insulin, and by building muscle, which helps the body use insulin more efficiently.
A systematic review of 11 studies found an association between increased physical activity levels and lower chances of developing insulin resistance. Try to at least meet the CDC’s minimum recommendation of 150 minutes per week of moderate-intensity physical activity.
According to a study funded by the National Institutes of Health, people at high risk of developing Type 2 diabetes could reduce that risk by losing 5 to 7 percent of their weight (10 to 14 pounds for someone who is 200 pounds). They did that through being more active and implementing dietary changes.
Not sure how to start? Take a look at the CDC’s PreventT2 program, which is a year-long program that includes diet and exercise advice. Research shows that programs such as this help with calorie reduction, weight control and physical activity, and they can reduce the risk of developing Type 2 diabetes by 58 percent. The program is covered by many health plans and Medicare Part B.
One good thing is that there are several possible diet plans that can help reverse insulin resistance.
“We learned from our evidence review for the American Diabetes Association’s Consensus Report on Nutrition Therapy for Adults With Diabetes or Prediabetes that the most robust evidence available to prevent Type 2 diabetes are for low-fat, Mediterranean-style and low-carbohydrate eating plans,” says registered dietitian Alison Evert, manager of nutrition and diabetes education programs for the University of Washington Medicine primary care in Seattle and one of the authors of the report.
So, the question isn’t, “Which eating plan is right?” It’s, “Which eating plan is right for you?” Evert says many different plans can work if they emphasize non-starchy vegetables; minimize refined grains and added sugars; and rely on whole foods over highly processed foods as much as possible.
The eating plan also needs to be one that you can stick with. It should include foods that are available, affordable and enjoyable, so you have the greatest chance of following it for the long term to sustainably manage your medical conditions.
“Wholesale changes or restrictive ‘diets’ don’t typically stand the test of time,” says Warshaw. Remember: Your goal isn’t just to reverse insulin resistance, it’s to do so indefinitely. The right eating plan and exercise habits can’t be short-lived, or insulin resistance will quickly return and lead to prediabetes.
“Start slowly and steadily to put lifestyle changes into place to slow the pace or stop this continuum in its tracks,” Warshaw says. “The earlier you can nip this situation in the bud, the better.”