What Is Insulin Resistance? Symptoms, Causes, and Diet for Reversal

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The body naturally produces insulin to help keep blood sugar (also called "glucose") within safe levels. But sometimes the body doesn't respond to the effects of insulin. When this happens, it's called insulin resistance.

Here, we'll discuss what insulin resistance is, how it can cause complications like Type 2 diabetes, and how you can prevent and even reverse it with lifestyle changes.

What is insulin resistance?

Insulin resistance happens when cells become resistant to the effects of insulin. Here's why that matters.

Insulin is a key hormone in the body

Insulin is a hormone that regulates metabolism. More specifically, it helps the body balance its main source of energy: glucose. Here's how it works:

1. Insulin is made by an organ called the pancreas, which sits behind the stomach. It releases insulin into the bloodstream after a snack or a meal. It also does this when it detects that your blood glucose levels are high.

2. The burst of insulin sends the glucose you've just absorbed from your meal into cells, where it's needed for fuel. Whatever glucose is left over is stored in muscle cells for later.

3. Both of these insulin functions help keep glucose levels steady in the blood and in the cells that use it.

When this system is working properly, your blood glucose levels should be kept within safe limits every hour of every day, whether or not you've just eaten.

Insulin resistance causes dangerously high blood glucose levels

When cells in the body lose their sensitivity to insulin, the body is no longer able to regulate its energy supply. This leads to a domino effect that looks something like this:

1. Glucose does not get into the cells where it is needed as fuel.

2. Extra glucose is not stored for later.

3. Glucose starts to pile up in the blood.

4. As high blood glucose levels persist, the pancreas releases more insulin, in an attempt to process the excess glucose.

5. Eventually, the pancreas can't keep up, and blood glucose levels continue to rise unchecked.

The health complications of insulin resistance are due to the combination of high blood glucose and high insulin levels.

What causes insulin resistance?

The exact cause of insulin resistance is not known. But there are many risk factors that can increase a person's risk of insulin resistance. Some of the most common risk factors include:

• Having a body mass index (BMI) that is considered overweight or obese, especially with excess abdominal (belly) fat

• Belonging to Black, Asian, and/or Hispanic ethnic groups

• A family history of insulin resistance or diabetes

• Diabetes in pregnancy

• Polycystic ovary syndrome (PCOS)

• A diet high in carbohydrates or sugar

• A sedentary lifestyle

• High blood pressure, heart disease, or stroke

• Abnormal cholesterol levels

• Steroid medication use

• Chronic stress

What are the signs and symptoms of insulin resistance?

There are usually no symptoms of insulin resistance in the early stages. Over time, the combined high blood glucose, high insulin levels, and insulin resistance can lead to complications in multiple body systems.

The symptoms a person experiences will largely depend on the underlying cause of insulin resistance in their body and the complications that develop.

Some people with insulin resistance may have one or more of these subtle signs:

• Irregular menstrual cycle

• Hirsutism (excessive body hair)

• Acanthosis nigricans (thick, dark patches of skin in skin folds or creases)

As glucose levels build up in the blood, the body responds by trying to remove it. It tries to store the excess in the liver and muscles. And then it stores excess glucose as body fat. So, weight gain is also a sign of insulin resistance.

If you have experienced any of these symptoms, speak with your primary care provider to determine if you need to be checked for signs of insulin resistance.

What are the complications of insulin resistance?

Despite the fact that there are often no symptoms early on, insulin resistance can affect the body in a great many ways. Most importantly, insulin resistance is the main cause of:

• Prediabetes

• Type 2 diabetes

• Metabolic syndrome

In the U.S., roughly 1 in 3 adults over the age of 18 has metabolic syndrome or prediabetes.

There can be other complications too, including:

• Coronary artery disease

• Fatty liver disease

Metabolic syndrome

This is one of the most severe complications of insulin resistance. Metabolic syndrome is a chronic condition that groups together:

• High cholesterol

• High blood pressure

• High blood glucose levels (which can lead to prediabetes and Type 2 diabetes)

• Excess body fat around the waist

Metabolic syndrome involves many different body systems and can cause health problems, such as heart disease, diabetes, and stroke.

Prediabetes and Type 2 diabetes

Prediabetes and Type 2 diabetes develop when high blood glucose levels persist over time. It is possible to have blood glucose that is higher than what is considered to be safe and have no symptoms. This is often the case if you have prediabetes.

Prediabetes can progress to Type 2 diabetes if it is not treated.

Type 2 diabetes is diagnosed when blood glucose levels rise higher than in prediabetes.

Prediabetes and Type 2 diabetes are especially serious effects of insulin resistance. That's because they increase the risk of complications, including:

• Heart disease

• Heart attacks

• Strokes

• Kidney damage

• Eye damage

• Nerve damage

You can see how when a person has prediabetes or diabetes and metabolic syndrome, the risks of health complications can rapidly stack up.

Is there an insulin resistance test?

Unfortunately, there is no insulin resistance screening test. Healthcare providers can use a blood glucose test or hemoglobin A1C test to determine if you are at risk for prediabetes or Type 2 diabetes.

In the early stages of insulin resistance, your blood sugar levels may still appear normal. So, a blood glucose or hemoglobin A1C test is not always a reliable test of insulin resistance. A combination of your symptoms, blood tests, and physical exam will help your healthcare team determine if you are showing signs of insulin resistance.

Can you reverse insulin resistance?

On the bright side, lifestyle changes can help improve insulin sensitivity and even reverse its effects.

Insulin resistance and diet

Carefully choosing what you include in your diet is an important way to help with insulin resistance and to avoid high blood sugar. The American Diabetes Association (ADA) often recommends talking with a professional like a dietician to improve your diet if you have prediabetes or diabetes.

High-protein, low-carbohydrate diets are recommended, because protein helps keep your body's blood glucose levels stable. High-carbohydrate diets can cause spikes in blood glucose levels that only make insulin resistance worse. Being insulin resistant doesn't necessarily mean you have diabetes, but following a meal plan recommended by the ADA can help improve insulin sensitivity.

If you're eating to reduce your insulin resistance, stick to a diet high in protein and low in sugar. This can include foods like:

• Meats and poultry (chicken, fish, and eggs)

• Low-fat dairy products (low-fat yogurt, low-fat cheese)

• Nuts

• Vegetables

• Whole grains

Insulin resistance and weight loss

Losing weight through exercise and a nutritious diet can help your body respond better to insulin. Even small changes can help reverse insulin resistance. And, if you continue these habits over time, you can delay or prevent diabetes.

These suggestions can be helpful goals for losing weight to avoid insulin resistance:

1. Engage in at least 30 minutes of physical activity most days of the week. Exercise is one of the fastest and most effective ways to reverse insulin resistance.

2. Eat a balanced diet emphasizing vegetables, proteins, and low-fat dairy. Moderating your carb intake can help with weight loss and decreasing insulin resistance.

3. Lose weight, especially around the middle, if possible. Losing weight around the abdomen not only improves insulin sensitivity but also lowers your risk of heart disease. Avoiding a sedentary lifestyle and engaging in consistent exercise has been shown to decrease excess weight in the midsection.

Keep in mind that many "fad diets" promote losing weight quickly through diet or exercise patterns that are not sustainable. Making small but consistent long-term changes in your diet and your exercise regimen is often the best way to lower your risk of insulin resistance.

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