All About Insulin Resistance

Written by: Ryah Nabielski, MS, RDN


You’ve probably heard about insulin resistance before, but what is it? Insulin resistance is a metabolic dysfunction that plays a significant role in weight gain, inflammation, and chronic disease. It develops slowly over time, and you may not be aware it’s going on until years down the road when you get a diagnosis. 

The good news is that you can often prevent insulin resistance and, in many cases, even reverse the process. It takes dedication and some significant changes to nutrition and lifestyle habits. 

In previous articles, we’ve talked about blood sugar balance, and today, we’ll dive into insulin resistance, what it is, why it happens, and what you can do about it. Keep reading to learn more about: 

  • What is insulin?
  • What is insulin resistance? 
  • Symptoms of insulin resistance
  • The link with chronic disease
  • Insulin resistance causes
  • The connection with weight 
  • An evolutionary perspective
  • How to improve insulin sensitivity with nutrition, lifestyle, and supplements

Let’s get started! 


What is Insulin? 
Insulin is a hormone made by the pancreas that lowers blood sugar levels, among other actions. 

When you eat carbohydrates (starches and sugars), the pancreas releases insulin into the bloodstream. When insulin binds to cells, it allows glucose (blood sugar) to enter. Then, cells use glucose immediately for energy or store it as fat. 

After eating, glucose levels spike. Insulin is the reason that glucose levels come back down an hour or two after meals. 

For good blood sugar balance, you need insulin! 


What is Insulin Resistance?
Insulin resistance is a dysfunctional metabolic state where cells become “resistant” to insulin’s message. 

When blood sugar levels are high, more insulin needs to be released. When this is the typical pattern over time, cells (like fat and muscle cells) can’t keep up with the high insulin signal and become “numb” to its message. The cells can’t access glucose efficiently for energy, which keeps blood sugar high after meals. 

The results are elevated blood glucose and insulin, creating stress, inflammation, and disease risk.   


Insulin Resistance Symptoms
Insulin resistance occurs gradually over time. There may be no symptoms in the early stages, and lab work may still be considered normal. Insulin resistance begins even before blood sugar levels are in a diagnosable category. 


Mid stages of insulin resistance are consistent with metabolic syndrome, a collection of signs including: 

  • Elevated fasting blood glucose (100 mg/dL or higher – in the prediabetes range)
  • Elevated blood pressure (130 mm Hg or higher over 85 mm Hg or higher)
  • Elevated triglycerides (150 mg/dL or higher)
  • Elevated waist circumference (35 inches or more for women and 40 inches or more for men)
  • Reduced HDL (less than 50 mg/dL for women and less than 40 mg/dL for men)

All this could leave you feeling low energy, increased hunger and cravings, and weight gain. 

Insulin Resistance and Chronic Disease 
Chronic diseases often take many years to develop. Diabetes and heart disease, diagnosed later in life, may have roots in insulin resistance that began decades earlier. 

As insulin resistance progresses, you may see:

  • Type 2 diabetes 
  • Heart disease
  • Cancer
  • Non-alcoholic fatty liver disease (NAFLD)
  • Polycystic ovarian syndrome (PCOS)
  • Weight gain and difficulty losing weight
  • Chronic inflammation 

Causes of Insulin Resistance
Several theories exist about the exact mechanism that causes insulin resistance to occur, but we still don’t fully understand how the body changes from a healthy insulin response to an unhealthy one. It may have to do with going past a personal fat threshold when fat accumulates in the liver. Recent research suggests microbiome changes may also play a role. 

Nonetheless, the drivers of insulin resistance are primarily lifestyle factors, including:

  • Excess carbohydrate intake, especially from ultra-processed foods
  • Sedentary lifestyle, lack of exercise
  • High stress and chronic stress (stress increases blood glucose)
  • Poor sleep quality, not enough sleep
  • Excess weight, especially around the midsection 

Insulin Resistance and Weight
While insulin and weight have a strong correlation in many cases, insulin resistance can also occur in “normal” weight people. (I use quotations because weight categories are determined by body mass index – BMI – which has limitations and doesn’t account for body composition.) 

Additionally, in some cases, people will be considered overweight by BMI standards but are metabolically healthy. This shows how much personal variation there can be and why body size doesn’t determine health. 


Is Insulin Resistance Natural?
The body is obviously predisposed towards insulin resistance, so is it by design? From an evolutionary perspective, insulin resistance may have been an advantage. 

When humans hunted and gathered, sugar (from fruit) was only available in the late summer. They would eat as much as possible, shifting towards insulin resistance. This change in metabolism helped them store fat, which increased their chance of survival through the winter. 

The modern food environment lends itself to insulin resistance, but there is no winter, so to speak. For many, there is no food scarcity or fasting period to counteract the metabolic change. So, while insulin resistance may have evolved to be a temporary, beneficial state, it no longer fits the environment and hinders human health instead of supporting survival. 

There are some other examples of natural insulin resistance. Women tend to be more insulin resistant during the second half (luteal phase) of the menstrual cycle. This adaptation supports fertility and pregnancy. It turns out that estrogen is protective against insulin resistance, and as estrogen declines in perimenopause and menopause, insulin resistance increases, requiring more lifestyle support to counteract it. 

 

How to Improve Insulin Sensitivity 
Insulin sensitivity is the opposite of insulin resistance. Insulin sensitivity means the cells are responsive to insulin’s message and well-fueled. The optimal metabolic state benefits health, weight, and longevity.  

Here are some strategies for maintaining and improving insulin sensitivity:

  • Look for trends. At your annual physical, you likely get a fasting blood glucose test. Look for the trends instead of waiting for a doctor to tell you something is out of range. If, over time, your fasting blood glucose begins trending up, you can intervene before you even get to a diagnosis. The earlier you are on the insulin resistance train, the easier it is to reverse. 
  • Exercise. Building exercise into your daily and weekly routine supports insulin sensitivity. Exercise benefits insulin sensitivity for up to 72 hours after a workout! The type of exercise and intensity are up to you; cardio and strength training benefit metabolic health and body composition. Timing also matters; a short walk after meals helps reduce the blood sugar spike and promote balanced blood sugar. 
  • Eat for blood sugar balance. The types of carbohydrates you choose (whole vs. processed) and meal composition (including protein, fiber, and healthy fats) support blood sugar balance and insulin sensitivity. The research shows that an anti-inflammatory eating pattern, such as the Mediterranean diet, helps improve insulin sensitivity. This is a whole-food eating pattern utilizing fresh, local, and seasonal foods. 

Cooking more at home helps shift the diet towards more whole foods and quality ingredients. However, you don’t have to give up convenience for products that support metabolic health; you just need to be a savvy consumer who reads ingredient lists. You can’t beat Twenty2 Nutrition Whole Food Bars created with thoughtful ingredients and balanced macronutrients for a satisfying snack. 

  • Rest digestion overnight. With so much food availability, getting into a grazing pattern is easy. However, resting your digestion between meals (at least some of the time) and overnight supports “metabolic flexibility,” where the body can shift into using fat (including body fat) for fuel instead of always relying on glucose and insulin. This approach doesn’t need to be exact, but you could work towards not eating from dinner to breakfast the next day or for about 12 hours overnight. Please discuss the details with your doctor or nutritionist for personalized guidance. 
  • Consider supplements. Well-placed supplements can enhance the benefits of a healthy lifestyle. Some options to consider include:

Understanding insulin resistance helps you take charge of your health today and into the future. It’s not complicated, but a healthy, flexible metabolism requires good habits and self-care. It doesn’t have to be all or nothing either; start with a small change like taking a family walk after dinner. 



This article is for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified healthcare provider before changing your diet or beginning a new supplement, especially if you are pregnant or breastfeeding, take medication, or have a medical condition. 


Ryah Nabielski, MS, RDN is a Registered Dietitian, functional nutritionist, writer, and recipe creator. Ryah helps clients use a natural, food-as-medicine approach to improve fertility, pregnancy, hormone balance, autoimmunity, and discover a healthy relationship with food and body. Learn more about Ryah and her private practice at econutrition.co.



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Morgan Snyders
Posted on July 15, 2024
Morgan Snyders
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