Insulin Resistance and Weight Gain

Insulin Resistance and Weight Gain

Medically reviewed by Dr. George Kosco, DO on May 20, 2021

Is insulin resistance caused by weight gain, or is weight gain the result of being insulin resistance?

Whichever way you look at it, insulin resistance and weight gain are linked together.

In its simplest terms, insulin resistance is a condition in which your cells don’t respond as they should to insulin.

This “resistance” leads to fatigue, cravings and easy fat storage.

Here’s how it works:

Insulin Resistance Explained Simply

What Is Insulin’s Job?

Insulin is a hormone that plays an important role in metabolism because it determines what happens to the digested carbohydrates you eat.

When you eat a carbohydrate, enzymes in your digestive tract break it down into its simplest form, which is sugar.

That sugar gets transported to your bloodstream where it becomes blood sugar or blood glucose.

How quickly sugar goes into your blood depends on what type of carbohydrate you eat.

Complex carbohydrates, like oats, brown rice, quinoa, potatoes, beans, and vegetables must be broken down before they can enter your blood. This extra step allows the sugar from complex carbs to slowly trickle into your blood over time.

Simple carbohydrates, like cookies, cakes, and candies are already in their basic form, so they rush into your bloodstream like cars piling onto the highway during rush hour.

Your body is not happy when there’s a flood of glucose rushing into your blood, so your pancreas secretes insulin to carry the glucose out of your blood and into your cells.

There are three cells that receive glucose:

  1. Liver cells
  2. Muscle cells
  3. Fat cells

Your liver and muscle cells cannot hold a lot of glucose, so if you eat a lot of simple carbs, most of that sugar gets dumped into your fat cells.

I like to think of insulin as the doorman to your cells. When insulin and glucose arrive at your cells, insulin opens the door to allow glucose to enter.

In a healthy body, this system works great.

  • Your blood is happy because it got rid of the extra glucose.
  • Your cells are happy because they have glucose to store for future energy.

In a body that’s insulin resistant, the system hits a roadblock…

The Insulin Resistant Body

If your body is insulin resistance, your cells ”resistant” insulin.

Insulin carries glucose to your cells, knocks on the cell door, but nothing happens.

It’s as if the liver, muscle and fat cells lock their doors, and ignore insulin’s knock.

This creates two problems:

  1. With nowhere to go, glucose builds up in your bloodstream resulting in chronic high blood sugar or pre-diabetes.
  2. Without glucose, your cells can’t store energy; as a result, you feel low on energy and you crave energy foods (i.e. carbohydrates).

Your pancreas tries to correct the problem by pumping out more insulin to force the cell doors open, which creates more problems:

  • Increased insulin blocks fat burning.
  • Increase insulin pushes fatty acids from the blood into fat cells.
  • By the time insulin busts down the doors, there is so much glucose in your blood that it pours into your fat cells.

With this cascade of problems, it’s easy to see how insulin resistance and weight gain are linked.

If this continues, the pancreas eventually wears out and stops producing insulin. As a result, blood glucose levels skyrocket, and you’re faced with type 2 diabetes.

Factors That Cause Insulin Resistance


One of the main causes of insulin resistance is obesity, especially when there is a lot of fat carried in the abdomen.

Belly fat releases fatty acids into the blood; this high level of blood fats is thought to be a major cause of insulin resistance.

Lack of exercise.

Exercise works the muscles, which need glucose to function. Inactivity creates a low demand for glucose, so glucose builds up in the blood.


Eating inflammatory foods increases oxidative stress, which leads to insulin resistance.

Lack of sleep.

Sleep deprivation makes the cells less sensitive to insulin.

Imbalance of gut bacteria.

The importance of bacteria in the intestinal tract is just starting to be understood, but there is strong evidence that shows a low level of good bacteria contributes to inflammation, insulin resistance, obesity, and general poor health.

Too many simple carbs.

Eating a diet high in simple carbohydrates causes blood sugar spikes that tax the pancreas.

Fruit sugar and insulin resistance.

Fruit contains a type of sugar called fructose.  Fructose and glucose are not processed the same way in your body.

Fructose is processed by your liver. When it arrives, it’s either turned into glycogen (i.e. stored glucose) or fat.

If you eat too much fruit, it can lead to insulin resistance in the liver, so…

Should you give up fruit?

No, but limiting fruit will help with insulin resistance. Fruit is a valuable part of a healthy diet because it adds flavor, fiber, and nutrients.

According to many experts, a healthy person should limit their intake of fructose to 25 grams a day, and an insulin resistant person should cut their intake to 15 grams.

If you’re healthy, your daily intake of fruit could include an apple (9.5 grams of fructose), a cup of blueberries (7.4 grams of fructose), and a banana (7.1 grams of fructose).


Fruit is a healthy addition to your diet when eaten in moderation, the problem is that fruit is not the only food that contains fructose.

Processed snacks, baked goods, and soda are loaded with high fructose corn syrup (HFCS). HFCS is a processed sweetener and food preservative made from cornstarch.

High Fructose Corn Syrup & Insulin Resistance

Many people overload their bodies with high fructose corn syrup foods, which can have three or more times the amount of fructose found in fruit.

Consuming these high-fructose snacks leads to insulin resistance, leptin resistance, weight gain, metabolic syndrome, heart disease, and cancer.

(In his younger years, Steve Jobs was a fruitarian meaning his diet was 100% fruit. There are those that think his high-fructose diet contributed to the pancreatic cancer that eventually took his life.

Aston Kutcher might admit the connection seems real. When he was preparing for his movie role as Steve Jobs he adopted a fruitarian diet, which landed him in the hospital.)

How To Fix Insulin Resistance

Fortunately, insulin resistance can be fixed, but the problem needs to get under control before it leads to type 2 diabetes.

The fix involves lifestyle changes:

  • Sleep at least 7 hours a night. Sleep deprivation causes your cells to be less receptive to insulin.
  • Exercise regularly. Exercise improves the uptake of glucose by your muscles, which keeps the level of glucose low in the blood.
  • Lose weight. Losing weight, particularly belly fat, reduces the fatty acids released into the bloodstream.
  • Reduce your intake of sweetened drinks and processed snack foods. Limiting these foods lowers your intake of high fructose corn syrup.
  • Choose slow-digesting carbohydrates. Carbohydrates that are high in fiber digest slowly in your system, which provides a gradual increase in blood glucose. Include vegetables, beans, nuts and seeds in your daily diet.

The Bottom line on Insulin Resistance and Weight Gain:

Controlling your weight and eating a healthy diet can eliminate insulin resistance.

For 4 daily habits to control insulin resistance and make weight loss easier, watch my free video series here.

About the Author

Dr. Becky Gillaspy, DC graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991.

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