The Link Between Intermittent Fasting and Insulin Resistance

intermittent fasting insulin

Your body is an astounding biological machine that performs thousands of behind the scenes functions so you can feel, look, and be your best. They’re all vital to your health and wellness, and hormones are no exception.

You create and circulate nearly 70 hormones, but insulin has the most significant effect on your health. Insulin helps fuel your body, and it’s a crucial factor in your heart health and your ability to lose weight. However, when insulin levels peak too high, you could increase your risk of insulin resistance. 

How Insulin Works?

Your body’s cells require glucose for energy, but most cells cannot absorb glucose directly, so that’s where insulin comes in. When you eat, carbohydrates in your food break down into glucose (sugar). Your bloodstream absorbs the glucose and raises your blood sugar levels. This increase in blood sugar signals your pancreas to create and distribute insulin into your bloodstream. 

Next, insulin attaches to your cells, and acts as a key to unlock them and allow sugar to enter. Then your cells convert the sugar into usable energy. If your bloodstream contains more sugar than your body needs, insulin will signal your body to store the excess glucose in your fat cells. That way, you’ll have an energy source to use when your blood sugar runs low between meals or while you sleep.

 Here’s the cycle:

  1. You eat a meal 
  2. Your body breaks carbohydrates down into glucose
  3. Glucose causes a spike in your blood sugar levels
  4. Your pancreas releases insulin
  5. Insulin attaches to your cells to allow glucose absorption 
  6. You store remaining glucose in your fat cells

Insulin helps you maintain balanced blood sugar levels. It prevents your glucose levels from getting too low (hypoglycemia) or too high (hyperglycemia), which ensures you function at your best.

fasting insulin resistance

What Is Insulin Resistance?

Constant exposure to insulin causes your cells to resist insulin so they no longer do a good job of removing glucose from your bloodstream. Over time, insulin resistance can increase your blood sugar.

Your pancreas will continue to release insulin in an attempt to return your blood sugar to healthy levels. Over time, your pancreas will be unable to meet the constant demand for insulin,causing a downward spiral of elevated blood sugar levels, which can have negative impacts throughout your body. 

How Insulin Resistance Develops?

Researches have yet to indicate a single cause of insulin resistance; however, a diet rich in sugar and processed carbohydrates may be to blame. When you eat a meal rich in carbohydrates, sugar rapidly enters your bloodstream and a rush of insulin follows. If sugar continues to enter your bloodstream, your pancreas will continually release insulin; but your pancreas can’t keep that up forever. 

Alcohol and caffeine, and soda are also culprits that can increase your blood sugar levels. And so can too little exercise, poor sleep patterns, and elevated stress levels. 

Insulin Resistance Symptoms? 

The only way to know if you’re insulin resistant resistance is to have your doctor run blood tests.

But you may see signs such as:

  • Fatigue
  • Extreme thirst 
  • Constant hunger, even after meals
  • Frequent urination
  • Tingling sensations in your hands or feet
  • Increased infections or illness

Dangers of Insulin Resistance? 

Insulin resistance causes an imbalance between the storage and uptake of glucose in  your cells, and causes a high concentration of sugar in your blood. When your blood sugar levels rise above a healthy range, it puts you at risk of diabetes.

Diabetes is a disease classified by having chronically high blood sugar. If your blood sugar rises above normal levels, but isn’t high enough to signify diabetes, your doctor will refer to it as prediabetes. According to the Centers for Disease Control and Prevention (CDC), roughly one in three Americans are prediabetic.

intermittent fasting insulin resistance

Intermittent Fasting and Insulin 

Intermittent fasting is an eating style where you alternate between periods of eating and fasting. This pattern offers a plethora of weight loss and other health benefits, but intermittent fasting’s primary benefit is how it affects your insulin levels. 

When you eat, much of your food is broken down into glucose, raising blood sugar levels, thus raising insulin levels. If you are constantly eating, you are constantly raising your insulin levels.

When you fast, it allows your body a chance to stabilize it’s insulin levels, which gives your pancreas a rest from producing insulin. If you follow an intermittent fasting (IF) lifestyle, you can promote healthier insulin levels. 

How Can Intermittent Fasting Reduce Insulin Resistance?

Intermittent fasting’s effect on insulin sensitivity has been a hot topic in recent years. In a 2018 study, researchers found a link between therapeutic fasting and reversing insulin resistance, permitting patients to wean off insulin therapy without altering their blood sugar levels. This link between insulin and fasting has also helped patients shed significant amounts of body weight and reduced their waist circumference. 

A secondary study which analyzed intermittent fasting and insulin resistance found participants who fasted saw a 3-6% reduction in their blood sugar, and lowered their insulin 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.

Best Intermittent Fasting Schedules to Reduce Insulin Resistance?

Popular intermittent fasting protocols range from fasting a few hours each day, fasting every other day, or doing a modified fast a few days of the week. So, there’s not a single, best way to fast to improve your insulin sensitivity. Studies conducted on humans show the best type of IF schedule is the one that works for you

One 2018 study showed a 18:6 fasting protocol (fasting for 18 hours of the day and eating for 6), improved insulin sensitivity in men with prediabetes. Another smaller study of patients with diabetes showed that various schedules of 24-hour fasts were beneficial to reducing insulin resistance. This review of 12 studies of patients following some form of IF showed insulin sensitivity improved, regardless of the type of fasting protocol they followed. 

IF is flexible. According to Jason Fung MD, founder of “The Fasting Method,” the most crucial factor of an IF diet is the fasted state will lower your insulin levels. The style of intermittent fasting that fits your lifestyle and is easiest to maintain will be your most effective way to fast for better insulin sensitivity. 

Combating Insulin Resistance

When cells become resistant to insulin, it can be harmful to your health. Intermittent fasting is a tool you can use to reduce your insulin resistance and lower your risk of disease. IF is not for everyone, and it’s important to consult a doctor before you make any significant changes to your eating plan.

Author's bio

Grace Trumpfeller

Grace Trumpfeller

Grace is an avid health and wellness advocate with nearly a decade of experience in the diet and nutrition industry. With a vast background in journalism and creative writing, her core focus is to empower individuals to reclaim their health and vitality by providing expert advice rooted in ...

7 comments

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.

I researched this and read P Clark response how her cycle started 7 days later. Omg mine started after 3 days in of 12 hour fasting. I’m going on almost a year of not having a cycle. Definitely gonna continue doing this.

Hi! May I ask how long you’re fasting during the day for? I am 24 and in the same situation as you, recent PCOS diagnosis with insulin resistance present 🙁

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