Diabetic man using glucometer to check blood sugar after insulin injection while wondering if insulin makes you gain weight

Does Insulin Make You Gain Weight?

Written on July 17, 2023 by Sendra Yang, PharmD, MBA. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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If you have diabetes or know someone with the condition, you have probably heard of insulin. Insulin therapy is an integral treatment option for many people with diabetes.[1] Over 37 million Americans are estimated to have diabetes, and one in five people do not know that they have the condition.[2] Diabetes is reported as the eighth leading cause of death in the United States.

As the American population ages and become more overweight or obese, the number of adults diagnosed with diabetes has increased.[2] Understanding insulin, how it works, and whether insulin makes you gain weight is essential in managing your diabetes. To address the question, “Does insulin make you gain weight?” let’s first review more about diabetes.

What Is Diabetes?

Diabetes is a chronic disease that results in elevated sugar in your blood.[3] If you have diabetes, your body does not make enough insulin or can’t adequately use it. Diabetes can affect how your body breaks down food into sugar and how the sugar is released into your bloodstream. There are three main types of diabetes [3]:

  • Type 1 diabetes (T1D): T1D is considered an autoimmune condition where the body attacks itself and stops making insulin. About 5% to 10% of people with diabetes have T1D. It is usually diagnosed in kids, teens, and young adults, and symptoms often develop quickly.
  • Type 2 diabetes (T2D): T2D is the most common type of diabetes. Around 90% to 95% of people with diabetes have type 2. T2D typically develops over years and is primarily diagnosed in adults. T2D occurs because your body does not respond adequately to the insulin your body makes. Type 2 can be prevented with healthy lifestyle modifications like losing weight, eating a healthy diet, and being more physically active.
  • Gestational diabetes: Gestational diabetes is a condition that develops in pregnant women who have never had diabetes. After giving birth, gestational diabetes typically goes away, though it increases women’s risks of developing T2D at a later time.

Over time, unmanaged diabetes with increased sugar levels in the blood can lead to severe health conditions like heart disease, stroke, vision loss, and kidney disease.[3] Diabetes is the leading cause of kidney failure, lower-limb amputation, and blindness in adults.

What Is Insulin and How Does It Work?

Insulin is a naturally occurring hormone produced by your pancreas, and it helps regulate your blood sugar levels.[4] Insulin helps transport the sugar in your bloodstream into your body cells to use for energy. If you are not able to make enough insulin needed by your body or your body cannot respond appropriately to insulin, then your blood sugar levels can get out of control, leading to diabetes.

Insulin can be made in the lab as therapy for diabetic patients.[5] The different types of insulin depend on when it reaches the bloodstream, the time it reaches maximum strength (peaks) in the blood, and how long it lasts in the body. Insulin is mainly administered as an injection, but an inhaled formulation is also available on the market in the United States.[5] Insulin can also be given in an insulin pump that can be attached to your body.[4]

What Are the Main Types of Insulin?

The main types of insulin include[4,5]:

  • Rapid-acting insulin begins to work within 5 to 20 minutes and can last for three to five hours. It works best about one to two hours after injection. The inhaled insulin formulation is considered a rapid-acting insulin.
  • Short-acting or regular insulin begins working 30 to 45 minutes after injection and lasts anywhere from five to eight hours. It peaks around one to four hours after injection.
  • Intermediate-acting insulin starts working around two hours and peaks between 4 and 12 hours post-injection. This insulin lasts 14 to 24 hours.
  • Long-lasting insulin reaches the blood in about one hour and peaks around 3 to 14 hours after injection. It can last up to 24 hours.
  • Ultra-long-lasting insulin takes around six hours to reach the blood and lasts up to two days.

Does Insulin Make You Gain Weight?

If you’re on insulin therapy, you probably wonder if insulin can make you gain weight. A reported 3 kg to 9 kg of insulin-associated weight gain, predominately fat tissue, occurs in the first year of initiating insulin therapy in type 2 diabetic patients.[6] The potential causes for the additional weight with insulin therapy in these patients include an increase in food intake because of the fear of low blood sugar levels, a reduction in eliminating sugar in the urine, and effects on weight and appetite control. Additionally, excess calorie intake that exceeds what your body needs can lead to extra sugar being transported into cells by insulin and stored as fat.[7]

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What Are Some Tips to Prevent Weight Gain with Insulin Therapy?

Although you can get weight gain with insulin therapy, there are ways you can lessen or prevent the additional weight gain.[7] You can choose to eat a healthy diet filled with nutritious foods, including fruits, vegetables, and nuts. Routine and regular exercise during most days of the week can also contribute to helping keep the weight off. Other tips to prevent weight gain with insulin therapy include[7]:

  • Count the calories you eat to ensure you’re not taking in too many. Select foods that are nutritious to eat and control your portion sizes.
  • Plan your meals ahead of time, and don’t skip them. Skipping meals can make you hungry and cause your sugar levels to be low.
  • Exercise to help burn the extra calories. Being physically active can also assist with making insulin work more efficiently.
  • Speak with your healthcare provider if weight gain becomes a significant issue for you. Don’t adjust your insulin doses without consulting with your healthcare provider first. You can potentially discuss other treatment options with them.

What Are Other Side Effects of Insulin?

Weight gain is not the only side effect of insulin therapy.[4] Other possible side effects involve injection site reactions such as lumps or pits, swelling, redness, or itching. Hypoglycemia or low blood sugar levels is also a potential side effect of insulin therapy. Contact your healthcare provider or seek medical help if you experience a serious side effect from insulin.

Telehealth for Weight Management via Everlywell

If you are concerned about gaining weight, Everlywell offers a telehealth program for weight loss help online. The program gives you access to regular one-on-one visits with a licensed clinician and lifestyle content and support for related health conditions. You can partner with a healthcare provider to discuss your weight goals and determine if GLP-1 medication is appropriate for you.

Everlywell also has an HbA1c at-home lab test that can help you monitor your A1c (an indicator of blood sugar levels over the past three months) to better understand your body’s glycemic control. The at-home lab test allows you to easily collect your sample in the comfort of your own home and mail it to a certified lab.

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  1. Diabetes treatment: Using insulin to manage blood sugar. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/diabetes/in-depth/diabetes-treatment/art-20044084. August 7, 2021. Accessed July 13, 2023.
  2. Diabetes quick facts. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/quick-facts.html. Last reviewed April 4, 2023. Accessed July 13, 2023.
  3. What is diabetes? Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/diabetes.html. Last reviewed April 24, 2023. Accessed July 13, 2023.
  4. Insulin: What is it, how do you take it, side effects. https://my.clevelandclinic.org/health/articles/22601-insulin. Cleveland Clinic. Accessed July 13, 2023.
  5. Insulin basics. Insulin Basics, American Diabetes Association. https://diabetes.org/healthy-living/medication-treatments/insulin-other-injectables/insulin-basics. Accessed July 13, 2023.
  6. Brown A, Guess N, Dornhorst A, Taheri S, Frost G. Insulin-associated weight gain in obese type 2 diabetes mellitus patients: What can be done? Diabetes Obes Metab. 2017;19(12):1655-1668. doi: 10.1111/dom.13009
  7. Insulin and weight gain: Keep the pounds off. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/diabetes/in-depth/insulin-and-weight-gain/art-20047836. September 1, 2022. Accessed July 13, 2023.
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