Iron Levels May Play a Role in Weight Gain — Here’s How

Have you ever wondered if your iron levels could be affecting your weight? Recent research suggests that iron deficiency may affect up to 1 in 3 adults. And it seems to be more common in people with a higher weight. So could iron deficiency be one of the causes of weight gain? 

Iron plays a major role in your body’s health, from keeping your energy levels up to helping your metabolism work smoothly. Iron is also a building block of red blood cells. So low iron can eventually lead to low red blood cell counts, a health condition called anemia.

Researchers are uncovering a complicated relationship between iron levels and weight. So, here, we’ll walk you through the connection between iron deficiency and weight and anemia and weight. And we’ll go over whether treatment for these conditions can help with weight loss.

Does iron deficiency cause weight gain?

Researchers have recently started looking into the connection between iron deficiency and weight. Scientists became interested in the link when they noticed that iron deficiency is more common in people diagnosed with obesity. 

But does iron deficiency cause weight gain? Or does weight gain cause iron deficiency?

Based on the current research, it appears that higher weight can contribute to low iron levels. There are several different theories about why weight gain leads to iron deficiency. But it’s likely related to the way increased body fat increases inflammation in the body. And this inflammation may make it harder for the body to store iron. 

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• Can you have iron deficiency without anemia? Yes, and it’s surprisingly common. But many healthcare professionals don’t test for iron deficiency until it causes anemia.

• Iron-rich foods: Learn the ways you can change your diet to increase iron intake and absorption. 

• How do you test for iron deficiency? Testing iron levels isn’t straightforward. And the best way to know may be to test something called a ferritin level.

Even though iron deficiency may not directly cause weight gain, it may contribute to it in certain ways. This is because iron deficiency can lead to:

• Low energy: Low iron can cause fatigue even before it starts to affect your red blood cell count. This may impact your physical activity or ability to get regular exercise.

• Slower metabolism: Iron plays a role in a process called thermogenesis, which is how your body burns calories to produce heat. So, when iron runs low, your metabolism can slow down and make it more difficult to burn calories. 

• Changes in thyroid function: Iron deficiency can lead to lower levels of thyroid hormone. And one of the symptoms of an underactive thyroid is weight gain.

• Restless leg syndrome: Some people with iron deficiency have symptoms of restless leg syndrome. In these cases, it may be challenging to get enough sleep. And this can lead to feelings of fatigue and less physical activity.

But the story doesn’t stop there. Many times, low iron levels can eventually lead to iron-deficiency anemia. This is a low red blood cell count that’s related to iron deficiency. And this condition can also have its own impact on weight. 

How does anemia affect your weight?

Anemia is a general term that means you don’t have enough red blood cells. This affects oxygen delivery to your body’s organs. Anemia may affect your weight in different ways, depending on the cause. 

Anemia can happen with or without iron deficiency. But iron deficiency is the most common cause. Other causes of anemia include things like:

• Blood loss

• Chronic health conditions

• Low levels of other nutrients like vitamin B12 and folic acid

Similar to iron deficiency, researchers have noticed a link between anemia and obesity — especially when the anemia is caused by iron deficiency. But as explained above, it’s more likely that weight gain leads to anemia rather than the other way around. 

Anemia might affect someone’s weight in a similar way that iron deficiency does. On the other hand, people with iron-deficiency anemia may also experience a loss of appetite, which could lead to weight loss.

Will increasing your iron help you lose weight?

Treating iron deficiency may help with weight management. There’s some research that shows treatment of iron deficiency may lead to weight loss. But this research included only a small sample of women. More research is needed to confirm whether treatment of iron deficiency causes weight loss — or if other factors are involved.

It’s also not entirely clear if weight loss happens because of higher iron levels or other factors. 

For example, getting more iron in your diet may help improve energy levels. This increase in energy levels may lead someone to be more physically active. So, it could be the increase in physical activity that leads to weight loss. Or, an increase in iron may improve thyroid function and metabolism for some people. 

So researchers still have a lot to learn about the connection between increased iron and decreased weight. And it’s also not known if increasing iron intake leads to weight loss for someone who isn’t iron deficient. 

What are the symptoms of iron deficiency?

Not everyone with iron deficiency has symptoms right away. And if they do, they can sometimes be hard to spot. Symptoms of iron deficiency without anemia include:

• Fatigue

• Too little energy for exercise

• Restless leg syndrome

• Hair loss

• Cravings for ice, also known as a form of pica

• Headaches

• Trouble concentrating

Symptoms of iron-deficiency anemia may include:

• Having pale or yellow skin

• Feeling extremely weak and fatigued

• Rapid heartbeat

• Pounding in the ears

• Shortness of breath, chest pain, or headache, especially with activity

• Desire or urge to eat ice or clay

• Sore tongue

• Nails that break easily

• Hair loss

If you think you may have symptoms of iron deficiency, talk to your primary care provider. Ask them to test your ferritin level. This is one of the first blood levels to drop when you have iron deficiency. 

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Written by:

Alexandria Nyembwe, PhD, MBA, RN

Alexandria Nyembwe has been a registered nurse since 2017. She has a background in cardiac care and has clinic experience as a nurse, serving people experiencing housing instability.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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