Does Insulin Make You Gain Weight? What To Do and Other Side Effects

Amy20MD 1

Medical reviewed by Amy Rogers, MD MPH FACPM

Preventive Medicine, Public Health, Lifestyle Medicine, Pandemic Response, Global Health

Insulin does not directly cause weight gain. However, it can affect cell metabolism, which, if not managed properly, can lead to weight gain

Maintaining a balance between insulin dosage, healthy eating habits, and regular exercise is critical to avoid weight gain and other potential side effects, such as low blood sugar levels. 

In this article, we will discuss insulin’s role in the body, its source, and how it impacts weight when taken.

What is insulin?

Insulin is a hormone produced by the pancreas to regulate sugar levels in the bloodstream (1). When you eat foods that contain carbohydrates, like bread, pasta, or rice, your body breaks them down into glucose. Glucose is a type of sugar that your cells use for energy. 

Insulin plays an important role in allowing glucose to enter the cells of the body, where it can be used for various cellular functions. Without insulin, glucose will remain in the bloodstream, leading to too much accumulation. The cells will then be unable to get the energy they require to function properly. 

The insulin secretion process helps regulate blood sugar levels and enables the body to utilize glucose efficiently, ensuring it functions effectively (2, 3).

When your body is unable to produce enough insulin or respond to insulin properly, glucose accumulates in your blood, resulting in high blood sugar levels. 

These high levels of blood sugar can cause various health issues, like diabetes, which can lead to further complications such as heart disease, blindness, kidney damage, and nerve damage (2, 4). 

Insulin is essential for maintaining balanced blood sugar levels and providing energy to body cells for optimal health and activity.

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Who needs insulin?

Diabetes is a medical condition in which the body fails to make enough insulin (Type 1 diabetes) or is unable to use insulin effectively (Type 2 diabetes) (1).

In Type 1 diabetes, the immune system, by mistake, will attack and destroy the insulin-producing cells in the pancreas. Therefore, individuals with Type 1 diabetes require insulin injections to survive.

In Type 2 diabetes, the body develops insulin resistance or doesn’t produce enough insulin. Thus, some people with Type 2 diabetes may require insulin to regulate their blood sugar levels in addition to diet management.

Proper blood sugar management is key to avoiding complications. Some people require insulin therapy, while others can control their condition with a balanced diet, regular exercise, and oral medications (1).

Types of insulin treatments

There are different types of insulin treatments available to manage diabetes. 

Rapid-acting insulin, such as Lispro, starts working soon after injection and is taken just before or after meals to control blood sugar spikes (5).

Short-acting insulin, such as regular insulin, takes effect within 30 minutes and lasts about 3 to 6 hours, helping to control blood sugar levels between meals (6).

Intermediate-acting insulin, such as NPH (Neutral Protamine Hagedorn), starts working in 1 to 2 hours and lasts 14 to 24 hours, providing coverage throughout the day and night (7).

Long-acting insulin, such as Insulin glargine, works slowly over 24 hours to establish a baseline insulin level, keeping blood sugar stable between meals and overnight. Your healthcare provider will determine the best insulin treatment for you based on your needs and lifestyle (8).

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How does insulin make you gain weight?

Insulin itself doesn’t directly cause weight gain. However, it can lead to weight gain indirectly by affecting fat accumulation and cell metabolism. 

When diabetics start using insulin, the sugar in the bloodstream can enter your cells. However, excess sugar remains in the blood when the body has used what it needs for basic functions. At this point, insulin moves the excess sugar into fat cells for storage. 

This means that if you use insulin and eat high amounts of carbohydrates, the excess sugar will be stored in fat cells, causing weight gain.

People with diabetes who require insulin therapy might gain weight if their insulin doses are not carefully adjusted or if they have an unhealthy lifestyle. 

It’s imperative to work closely with healthcare providers to manage insulin doses effectively and make lifestyle choices that promote overall health and well-being.

Does insulin make you hungry?

When people take insulin, it can cause their blood sugar to decrease, which may increase hunger if the blood sugar drops too low. However, insulin can also reduce hunger (9).

People with diabetes should work closely with their doctors to manage insulin and diet for optimal health and hunger control. 

What is the average weight gain while taking insulin?

Weight gain experienced by a person taking insulin can vary depending on factors like metabolism, insulin dosage, and lifestyle choices. 

Additionally, managed insulin doses can help maintain a healthy weight. If you are concerned about weight gain while taking insulin, talk to your healthcare provider. 

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How to stop insulin weight gain

To avoid gaining weight while taking insulin, it is crucial to maintain a balanced diet rich in:

  • Citrus fruits such as grapefruit and oranges
  • Leafy greens like spinach and arugula
  • Healthy fats such as avocado and flaxseed
  • Lean proteins such as fish and poultry
  • Whole grains such as oats and quinoa

Avoid sugary and high-calorie foods such as:

  • White breads
  • Donuts, cakes, and cookies
  • Pasta
  • White rice
  • Sugary fruit juice and sodas 
  • Breakfast cereals

Be sure to read all nutritional labels when buying anything processed to avoid added sugar or corn syrup. Buy sugar-free juices or drinks with no added sugar or corn syrup.

Regular physical activities such as walking, cycling, swimming, or yoga can help manage weight and improve overall health (10).

Other insulin side effects

Insulin injections may lead to certain side effects, such as redness or irritation at the injection site. Rotating the injection sites and using proper techniques is recommended to avoid such reactions.

What happens if you take too much insulin?

Taking too much insulin can lead to hypoglycemia, which is a condition that causes blood sugar levels to drop too low (10). This can result in symptoms such as shakiness, sweating, and confusion. If untreated, severe hypoglycemia can even cause loss of consciousness or coma. 

Consuming a fast-acting carbohydrate like juice or glucose tablets is recommended to manage the symptoms of diabetes. Properly managing diabetes requires closely monitoring blood sugar levels and adjusting insulin doses according to your healthcare provider’s instructions. This will help prevent the risk of hypoglycemia (11).

Signs and symptoms of hypoglycemia or insulin overdose (11):

  • Shakiness
  • Sweating
  • Confusion
  • Irritability
  • Dizziness
  • Hunger
  • Rapid heartbeat
  • Headache
  • Blurred vision
  • Weakness
  • Seizures (in severe cases)
  • Loss of consciousness (in severe cases) 
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Why you shouldn’t stop insulin abruptly?

It’s important to note that abruptly stopping insulin medication can lead to a condition called hyperglycemia, which is characterized by dangerously high blood sugar levels. 

Symptoms of hyperglycemia include:

  • Frequent urination
  • Excessive thirst
  • Exhaustion (12).

It’s important to consult with healthcare professionals before making any changes to insulin treatment to ensure effective diabetes management and prevent potential complications.

Can you get off insulin once you start taking it?

Adopting a healthy lifestyle can help Type 2 diabetes patients reduce or eliminate their need for insulin. This includes losing weight, improving their diet, and increasing physical activity (13). 

The effectiveness of changes made to treat diabetes may depend on the type and severity of the condition and the individual’s response to treatment. Therefore, it is important to collaborate closely with your providers to create a personalized treatment plan and regularly monitor blood sugar levels to determine the best course of action.

How long can a diabetic go without insulin?

When an individual with diabetes does not have sufficient insulin in their body, their blood sugar levels can significantly increase within a few hours. This can lead to symptoms such as extreme thirst, frequent urination, and fatigue. 

Those with Type 1 diabetes and certain people with Type 2 diabetes may develop a serious complication called diabetic ketoacidosis (DKA) within one or two days (14).

DKA is a life-threatening condition, and people with diabetes must take insulin as prescribed by their doctor regularly. This helps maintain blood sugar control and prevent complications.

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Does insulin therapy make you sleepy?

Fluctuations in blood sugar levels, such as hypoglycemia, caused by insulin therapy can lead to fatigue. Monitoring blood sugar levels regularly and adjusting treatment plans can prevent associated symptoms such as fatigue.

Is insulin therapy harmful to the kidneys?

Insulin therapy is not harmful to your kidneys. Instead, it plays a vital role in regulating blood sugar levels and preventing kidney damage that can result from uncontrolled diabetes (15).

What happens if you take insulin, but you don’t actually need it?

Taking insulin without medical guidance can result in dangerously low blood sugar levels, leading to symptoms such as shakiness, confusion, loss of consciousness, and, in severe cases, even death (16).

Can you reverse diabetes after taking insulin?

It is possible to reverse type 2 diabetes by making healthy lifestyle choices such as losing weight, eating healthy, and engaging in physical exercise, even if you have started insulin therapy (17). However, individual results may vary.

It is important to consult with your healthcare provider before stopping any medication. This will ensure your health and well-being and prevent any potential negative effects.


Insulin therapy does not cause weight gain by itself, but it can indirectly contribute to it if it is not balanced with healthy habits. 

To effectively manage weight and overall health while using insulin therapy, people with diabetes should follow a balanced diet, regularly engage in some form of exercise, and monitor their blood sugar levels closely. 

It is essential to work collaboratively with your health provider to create a personalized diabetes treatment plan that meets individual needs and supports long-term well-being. 

Remember, managing diabetes is possible when finding the right balance with a proper diet, taking medications as prescribed, and committing to a basic exercise routine to live a healthy and fulfilling life.

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Amy20MD 1

Medical reviewed by Amy Rogers, MD MPH FACPM

Preventive Medicine, Public Health, Lifestyle Medicine, Pandemic Response, Global Health

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