Can Anemia Cause Weight Gain?

It can be surprising to gain or lose weight for no apparent reason. Sometimes, the cause of the weight change has nothing to do with your eating habits. There could be a correlation between anemia and weight. That can leave you asking, "Can anemia cause weight gain?"

Have you considered clinical trials for Anemia?

We make it easy for you to participate in a clinical trial for Anemia, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Does anemia cause weight loss or gain?

Anemia can be a double-edged sword in terms of weight. If you are wondering whether anemia causes weight gain or not, anemia can make weight control difficult due to various circumstances. 

Fatigue is a major factor in anemia-related weight gain. For all types of anemia, particularly iron and vitamin deficiency anemia, symptoms such as exhaustion and lack of energy can make it difficult to exercise. A lack of physical activity can result in weight gain.

Burning fat requires sufficient oxygen, not to mention that people feel weak and can become winded more readily if they do not have enough oxygen. Anemia strains all the organs and makes it much harder to burn fat.

On the other hand, both unwelcome weight loss and the inability to put on weight can be symptoms of anemia. Iron deficiency anemia can impact your immune system, making you more prone to disease and infection. Therefore, you may be anemic and lose weight due to an underlying disease like cancer.

Understanding anemia

Anemia is a condition that occurs when your blood lacks sufficient healthy red blood cells (RBCs) to carry oxygen to the tissues of your body. Anemia affects roughly three million people in the US. People become anemic for three reasons:¹

  • Either their body cannot produce enough red blood cells,

  • Something is causing the red blood cells to degrade more quickly, or 

  • Blood loss exceeds red blood cell creation.

Doctors diagnose anemia through a standard blood test as low hemoglobin or hematocrit. Hemoglobin is an iron-rich protein found in red blood cells. It transports oxygen and distributes it all over your body. Your body does not get enough oxygen when you do not have enough RBCs or low hemoglobin. As a result, you may experience fatigue or other symptoms. 


You may experience the following symptoms depending on the cause and severity of your anemia:

  • Headache

  • Your ears are pounding or "whooshing"

  • Pain in bones, chest, belly, and joints

  • Dizziness

  • Breathing difficulty

  • Having pale skin

  • Cold fingers and toes

  • Weakness or fatigue

  • Rapid or irregular pulse


Anemia is diagnosed through a thorough medical history, physical exam, and blood work. Your doctor will order a complete blood count (CBC) test, which measures various components and characteristics of the blood. The CBC indicates the number and average size of red blood cells and the amount of hemoglobin. Low levels of hemoglobin or a lower-than-normal red blood cell count indicate anemia.

A blood sample can be analyzed to identify the type of anemia by examining variations in the size and form of the red cells, white cells, and platelets.

Low iron, hemoglobin, and weight: What is the connection?

Your body needs iron to make hemoglobin. With low iron, your body cannot manufacture enough hemoglobin in red blood cells to allow them to transport oxygen. It causes fatigue and shortness of breath.

The connection between low iron, body weight, and hemoglobin is apparent when low energy makes exercising and burning calories difficult, causing weight gain. Conversely, iron deficiency anemia may contribute to decreased appetite, resulting in weight loss. 

How iron levels are tested

Before the test, your doctor may instruct you to abstain from food and liquids for 12 hours. During the test, the doctor draws a small amount of blood from a vein in your arm into a test tube or vial. Your doctor can determine if your blood's iron level is too high or too low based on the test's results.

Complications for iron-deficiency anemia

Anemia, if untreated, can lead to a variety of health conditions, including:

  • Heart conditions: Anemia can cause an abnormal or rapid heartbeat (arrhythmia), leading to an enlarged heart or heart failure.

  • Obstetrical difficulties: Severe iron deficiency anemia in pregnant women can lead to early births and babies with low birth weight.

  • Low immune system: Iron deficiency anemia makes people more vulnerable to infections.

Treatment for iron-deficiency anemia

To cure iron deficiency anemia, your doctor may:

  • Advise modifying your diet or taking supplements

  • Inject iron into your body through a vein using intravenous, or IV iron

  • Treat the underlying illness if you have a chronic disease and prescribe medication such as erythropoietin stimulating agent (ESA) to aid in the production of more red blood cells in the bone marrow

  • Perform surgery to stop internal bleeding

  • Increase red blood cells and iron levels in your blood through blood transfusions

Ways to improve iron bioavailability

If you need to increase the quantity of iron in your diet, here are some techniques to help enhance absorption:

  • Take vitamin C alongside your iron source

  • Avoid consuming high-fiber foods or taking calcium supplements simultaneously as an iron source or with iron supplements. Fiber and calcium can both reduce iron absorption.

  • Choose an effective iron source. Animal sources of iron are two to three times more bioavailable to the body than plant sources.

  • It will be easier for non-heme iron to be absorbed if non-heme sources, including fruits, vegetables, nuts, rice, egg yolks, and beans, are consumed along with heme iron sources.

  • Avoid consuming red wines, coffee, tea, and other caffeinated beverages with meals or iron supplements since they inhibit iron absorption.

The lowdown

Weight management concerns result from several negative effects, including anemia, a major global public health issue. It is essential to monitor physical changes in your body, such as unexplained fatigue. Anemia is typically a temporary problem you can manage by modifying your diet or taking supplements.

Frequently asked questions

Does anemia affect metabolism?

Yes. Anemia can make you lazy by preventing oxygen from reaching your muscles and tissues, lowering your metabolism.

Is it hard to lose weight with low iron?

Yes. Low iron causes low energy, which may result in burning fewer calories and causing you to keep reducing your caloric intake to lose weight.

Can iron help you lose weight?

Yes. Your body uses iron to convert food into energy. Iron aids in the transportation of oxygen to every cell in your body, including the muscles. Consequently, you can burn fat.

  1. Anemia or iron deficiency | Centers for Disease Control and Prevention

Other sources:

Have you considered clinical trials for Anemia?

We make it easy for you to participate in a clinical trial for Anemia, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Discover which clinical trials you are eligible for

Do you want to know if there are any Anemia clinical trials you might be eligible for?
Have you taken medication for Anemia?
Have you been diagnosed with Anemia?