The Link Between Intermittent Fasting and Insulin Resistance

intermittent fasting insulin

The human body creates and circulates nearly 70 hormones throughout the body, but few have as much of an effect on overall wellness as insulin. In addition to helping fuel the body, insulin is a key factor in both weight loss and heart health. However, when insulin levels peak too high, the body is at risk of developing insulin resistance. 

Recent studies suggest that the answer to reducing insulin resistance — and keeping the body balanced — is with intermittent fasting. By introducing intermittent fasting patterns into daily healthy habits, we can not only regulate levels of this crucial hormone but also help combat risks of chronic diseases, such as diabetes. To learn more about the link between insulin and intermittent fasting, keep reading. 

What Is Insulin and How Does It Work?

Your body’s cells require sugar for energy, however, most cells cannot absorb sugar directly. This is where insulin comes in. After you’ve eaten a meal, carbohydrates in the food you’ve eaten are broken down into glucose, or sugar. This causes an increase in blood sugar levels, which then signals the pancreas to create and distribute insulin into the bloodstream. 

Next, insulin attaches to the body’s cells, acting like a key to unlock the cell and grant sugar access. From here, the cell can absorb the sugar and channel it into energy to power the body. If your body contains more sugar in its blood than it requires, insulin helps to store the excess glucose within the liver and will release it when your levels begin to run low, such as between meals. 

The cycle looks something like this:

  1. Food is eaten 
  2. Carbohydrates are broken down into glucose
  3. Glucose causes a spike in blood sugar levels
  4. Insulin is released by the pancreas
  5. Insulin attaches to cells to allow glucose absorption 
  6. Leftover glucose is stored within the liver

Insulin is necessary to prevent blood sugar levels from dropping too low, called hypoglycemia, or getting too high, known as hyperglycemia. As blood sugar levels spike, the pancreas will release more insulin to continue balancing the body. 

fasting insulin resistance

What Is Insulin Resistance?

Insulin resistance is a medical term which refers to the body’s cells becoming tolerant or resistant to insulin. Insulin resistance occurs when sugar builds up in the blood, reducing your cells’ effectiveness to take in glucose and transform it into energy. The longer this continues, the less your cells become able to attach to insulin. 

This means that the pancreas will continue to release more insulin in an attempt to balance your current blood sugar levels. However, over time, the pancreas becomes unable to keep up with the continuous creation of excess insulin to maintain the body’s increasing resistance. This causes continuously elevated blood sugar levels, which can have negative impacts throughout the body. 

How Is Insulin Resistance Developed?

Researchers have yet to indicate an exact motive behind insulin resistance, however, scientists believe a diet rich in sugar and processed carbohydrates may be to blame. A carbohydrate-heavy diet means that sugar is rapidly released into the bloodstream, which causes the pancreas to secrete a rush of insulin. If sugar continues to collect in the bloodstream, the pancreas can fail to produce an adequate amount of insulin and insulin resistance can occur. 

Additional culprits linked to insulin resistance development include alcohol and caffeine, which both create an accelerated increase in blood sugar levels, as well as sodas containing high-fructose corn syrup. Non-diet related factors connected with a rise in insulin resistance include too little exercise, poor sleep patterns, and elevated stress levels. 

What Are the Dangers of Insulin Resistance? 

Once insulin resistance begins, it can unbalance the release and storage of energy in the body and cause a rapid escalation of blood sugar levels. When blood sugar levels rise above a healthy range, it puts the body at risk of developing diabetes.

Diabetes is a disease classified by having a chronically high blood sugar level. When blood sugar is elevated to a higher level than normal but has not yet risen high enough to signify diabetes, physicians refer to it as prediabetes. According to the Centers for Disease Control and Prevention (CDC), roughly 1 in 3 Americans have been diagnosed with prediabetes. 

When prediabetes is not addressed, it increases the likelihood of ultimately developing Type 2 diabetes, a chronic disease that alters how the body processes blood sugar. 

intermittent fasting insulin resistance

How Can Intermittent Fasting Affect Insulin Levels? 

During intermittent fasting, an individual alternates between periods of eating and fasting. While this offers a plethora of benefits in terms of weight loss and lowering cholesterol, intermittent fasting also affects insulin levels. 

The reasoning behind this is quite simple. When we eat, carbohydrates are broken down into glucose, which then raises blood sugar levels. This causes an increase in insulin levels. Each time blood sugar levels in the body rise, more insulin will be released. Therefore, when we constantly eat, we are consistently raising our insulin levels.

A pattern of constant eating does not allow insulin levels to regulate. In comparison, a pattern of intermittent fasting allows insulin levels to healthily equalize, storing any access glucose and allowing the pancreas to rest between periods of eating. By adopting a lifestyle of intermittent fasting, you help maintain a healthy balance of insulin levels. 

How Can Intermittent Fasting Reduce Insulin Resistance?

Intermittent fasting and insulin sensitivity have been a hot topic in recent years, and for good reason. In a 2018 study, researchers developed a link between the efficiency of therapeutic fasting to reverse insulin resistance, permitting patients to wean off insulin therapy without altering their blood sugar levels. This link between insulin and fasting also allowed patients to shed significant amounts of body weight while also reducing their waist circumference. 

Moreover, a secondary study analyzing intermittent fasting and insulin resistance found that while fasting, blood sugar had been reduced by 3-6% and insulin had been reduced by 20-31%. Researchers involved with the study suggest that fasting is equally as effective as traditional calorie reduction methods to accelerate weight loss and protect heart health, and can also help inhibit the progression of Type 2 diabetes. 

When blood sugar levels spike and cells begin to become tolerant or sensitive to insulin, it can directly impact the body. By incorporating intermittent fasting tactics into healthy living habits, you can not only reduce insulin resistance but also improve weight management and decrease the likelihood of developing a disease. 

Continuing along the path of intermittent fasting is a health-conscious choice that will continue to benefit the entire body. To learn more about the influence of fasting on our health please refer to our complete health guide.


Loved this! I’m 22 and today is my 5th day of fasting. My goal is to stop the development of diabetes and PCOS (both run in my family and I was recently diagnosed with PCOS. I imagine diabetes will come next if I don’t make a change) ! Reading articles like this helps me stay focused and motivated! Well done, Grace!

Update: I finally got my period after 6 months of amenorrhea (no periods) just by fasting for 7 days! Good luck to anyone seeking solutions. Fasting is a game changer and I plan on making it a regular thing.