Anemia can affect your weight. However, any weight change that occurs is usually due to the condition’s impact on your lifestyle or appetite, or its underlying cause.

“Anemia can lead to weight changes in some cases,” says Brian Gans, MD, an internal and palliative medicine double board certified physician in Cheyenne, Wyoming.

If your body doesn’t have enough red blood cells, it’s difficult for your organs and tissues to get enough oxygen. This can lead to anemia and symptoms such as fatigue, weakness, and shortness of breath.

Feeling fatigued can make you less likely to be active, which may contribute to weight gain. Some people also report that treatment for iron deficiency anemia has contributed to weight gain, though some research has found the opposite.

“Additionally,” Gans says, “some types of anemia can cause a decrease in appetite or a change in taste, which can lead to a decrease in food intake and subsequent weight loss.”

More research has focused on the link between being at a particular weight and then getting anemia than the other way around.

Research does suggest an association between obesity and anemia — particularly iron deficiency anemia.

This is thought to be due to increased levels of a hormone called hepcidin affecting the body’s ability to absorb iron.

But weight changes can result from underlying causes of anemia or the condition’s effects on your activity and appetite levels.

For example, nutrient deficiency-related anemia can lead to weight loss. Conversely, weight loss can result in this type of anemia.

A chronic illness or disease such as cancer may also be associated with anemia and unexpected weight loss.

When it comes to weight gain linked to anemia, an underactive thyroid gland (hypothyroidism) and general fluid retention may be to blame.

“It’s important to note that weight changes aren’t always a symptom of anemia,” explains Gans.

Lots of other factors can cause or contribute to weight gain or loss.

Weight loss

Certain medical conditions and medications can lead to unplanned weight loss. Here are just some of the factors to be aware of:

Weight gain

Similarly, other medical conditions and medications, as well as certain lifestyle factors, can cause unexpected weight gain. Here are a few:

How do you know if you have anemia?

Common symptoms of anemia include:

Some people also experience the following with certain types of anemia:

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To treat anemia, a healthcare professional will first need to determine the underlying cause.

The cause may be nutritional, such as in iron deficiency anemia or pernicious anemia, where the body cannot absorb enough vitamin B12. Or it may be the result of an autoimmune disease or inherited condition such as sickle cell disease.

Once your doctor identifies the cause, they can develop a treatment plan. This may involve treatments such as iron or B12 supplements or injections.

In severe cases, they may recommend medications to boost red blood cell production.

If you’ve gained or lost weight as a result of anemia, there are several things to focus on alongside appropriate anemia treatment.

To address weight gain, Gans recommends eating a balanced diet that includes animal-based proteins, nutritional yeast, healthy fats, and fresh fruits.

Getting regular physical activity can also help.

“Speak with a healthcare provider you trust about what types of exercise are safe and appropriate for you,” says Gans. “If you’re experiencing unintended weight loss with anemia, it’s important to consume enough calories to meet your body’s energy needs.

“Speak with a health and nutrition professional to develop a meal plan that provides enough calories and nutrients to support your health.”

You can also opt for foods that are high in nutrients and calories, such as nuts, healthy oils, and avocados.

Weight can fluctuate slightly, but persistently losing or gaining weight when you haven’t changed your diet or activity levels can be a cause for concern.

“If you or a loved one are experiencing unexplained weight changes or other symptoms, it’s important to speak with a physician for a proper diagnosis and treatment plan,” says Gans.

This is also true if you have any other potential anemia symptoms, such as fatigue or dizziness.

Anemia can affect your weight, often as a result of its impact on your appetite or activity levels. The underlying cause of a particular type of anemia may also lead to weight loss or gain.

But lots of other factors can cause unexpected weight changes, including mental health conditions, certain diseases, and even some medications.

If you’re experiencing unexplained changes to your weight, consult a healthcare professional to see what’s going on and figure out the best course of action.

Lauren Sharkey is a U.K.-based journalist and author specializing in women’s issues. When she isn’t trying to discover a way to banish migraines, she can be found uncovering the answers to your lurking health questions. She has also written a book profiling young female activists across the globe and is currently building a community of such resisters. Catch her on Twitter.