Insulin Resistance and Nutrition
What Is Insulin Resistance?
Insulin is a hormone produced by the pancreas that helps regulate blood sugar. It helps cells use glucose from the blood after meals and also regulates glucose production by the liver. In insulin resistance, tissues such as muscle, fat and liver respond less effectively to insulin. The pancreas may compensate for this for a time by secreting more insulin. Over time, blood sugar may rise, and some people may develop prediabetes or type 2 diabetes.
Insulin resistance does not have a single cause. Genetic predisposition, excess weight, particularly fat accumulation around the abdomen, physical inactivity and certain health conditions may be associated with the risk. It is not a condition that can be explained solely by a person's eating habits.
What Are the Symptoms of Insulin Resistance?
Insulin resistance may not cause noticeable symptoms in many people. Hunger, cravings for sweets, tiredness after meals or difficulty losing weight do not, on their own, indicate insulin resistance; these symptoms may have other causes. Darkened, velvety skin in areas such as the neck or armpits may be associated with insulin resistance in some people. Assessment by a doctor is necessary for diagnosis and follow-up.
How Is Insulin Resistance Assessed?
Tests that measure insulin resistance are not always necessary in routine clinical practice. Fasting insulin or calculations such as HOMA-IR cannot establish a diagnosis on their own; their results may vary depending on the method used and individual characteristics. When screening for prediabetes and diabetes, a doctor may request fasting blood glucose, HbA1c or a 75 g oral glucose tolerance test (OGTT), taking the person's risk factors into account. Results from these tests may not agree with one another in different individuals.
People who are overweight or have obesity and have risk factors such as a family history of diabetes, high blood pressure, polycystic ovary syndrome, physical inactivity or abnormal blood lipid levels can discuss diabetes screening with their doctor. The ADA also recommends considering screening from age 35 in adults with no other risk factors.
Why Can Losing Weight Become More Difficult?
Weight management is influenced by many factors, including appetite, sleep, stress, medications, health conditions, daily physical activity levels and eating habits. Insulin resistance does not make weight loss impossible for everyone; it is also incorrect to say that weight loss is possible only through exercise. Sustainable changes to diet and physical activity that suit the individual may be beneficial. In some people with prediabetes who are overweight, a modest reduction in initial body weight may help reduce the risk of type 2 diabetes.
Which Health Conditions Are Associated with Insulin Resistance?
Insulin resistance may occur alongside conditions such as prediabetes, type 2 diabetes, high blood pressure, abnormal blood lipid levels and metabolic fatty liver disease. These associations do not mean that insulin resistance alone is the direct cause of these conditions. Risk is assessed in the context of the person's overall health and other factors. Insulin resistance alone is not used to change a cancer screening programme; cancer screening should be planned according to age, family history and relevant guidelines.
What Should You Eat If You Have Insulin Resistance?
There is no single diet or meal pattern that suits everyone. A nutrition plan should be developed according to the person's health, preferences and daily life. In general, it may be beneficial to eat minimally processed, fibre-rich foods such as vegetables, fruit, legumes and whole grains more often, and to limit sugary drinks and products high in free sugars. WHO recommends that free sugar intake account for less than 10% of daily energy intake and, if possible, be reduced to below 5%. This approach does not require eliminating all carbohydrates or fruit from the diet.
The number of meals varies from person to person. It cannot be said that everyone with insulin resistance needs to eat frequent small meals or that skipping the evening meal is appropriate. An individual eating pattern can be planned with a doctor or dietitian.
The Role of Exercise and Daily Physical Activity
Regular physical activity supports blood sugar control and overall metabolic health. WHO recommends 150–300 minutes of moderate-intensity or 75–150 minutes of vigorous-intensity aerobic activity per week for adults, along with muscle-strengthening activity on at least two days a week. People who are inactive can start at a low level and gradually increase their activity over time; suitable exercise should be determined according to the person's health.
Is Medication Necessary?
The need for medication is not determined solely by the term “insulin resistance” or a single laboratory result. The doctor considers blood sugar results, whether prediabetes or diabetes is present, other health conditions and the person's overall risk together. Medication may be considered in some high-risk cases of prediabetes; medications do not replace lifestyle changes.
For information about the tests used to assess diabetes and prediabetes, you can explore our diabetes test package. Your doctor should decide which tests are appropriate based on your symptoms and risk factors.