Biologics are an effective treatment for rheumatoid arthritis (RA). But like all medications, they come with the risk of side effects. This has caused some people with RA to wonder, “Do biologics cause weight gain?”

Knowing how biologics and weight gain are connected can help people make better, more informed decisions about their RA treatment. In this article, we’ll explore how different types of biologics may contribute to weight gain and some tips on how you can manage weight while taking this type of drug.

What’s the Connection Between Biologics and Weight Gain?

Biologics are a type of disease-modifying antirheumatic drug (DMARDs). They help treat RA by changing how your immune system works to slow down the disease.

Some people notice weight changes while taking biologics, but not everyone. Different biologics can affect weight in different ways. Weight changes might happen because these drugs can change your appetite and metabolism (how your body uses energy and stores fat).

But weight changes with RA aren’t always caused by treatments. They also can be caused by lifestyle factors or other, unrelated health conditions.

It’s important to know that weight changes after taking a biologic medication aren’t something to worry about. In fact, some research shows that a slight weight gain after using biologics may be a sign of reduced disease activity or that your RA is under control.

Which Biologics Cause Weight Change in Rheumatoid Arthritis?

On myRAteam, members often wonder about the connection between weight gain and biologics for RA. One member asked, “I read that biologics cause you to put on weight. Is that so?”

Another member said, “Everyone responds differently, but it’s not unusual to gain weight while on a biologic.”

There are four main types of biologics that are usually prescribed for RA. Each type affects weight differently. Research has shown that one type, tumor necrosis factor-alpha (TNF-alpha) inhibitors, can cause weight gain. Less is known about how other types of biologics can affect weight.

TNF-Alpha Inhibitors

TNF-alpha inhibitors work by blocking TNF-alpha, a protein that causes inflammation and affects the way immune cells work. Too much TNF-alpha can make the immune system overactive, leading to joint pain and swelling in people with RA. TNF-alpha inhibitors help reduce that inflammation.

TNF-alpha inhibitors may lead to weight gain, but these weight changes are usually small. In one large analysis of data from more than 1,000 people, researchers found that people gained between 2 and 5.2 pounds while taking different TNF-alpha inhibitors for various health conditions.

Keep in mind that these weight changes are small. On average, people gained about 3.5 pounds after one year and about 4 pounds after two years.

Not everyone will gain weight. These medications affect each person differently.

Sudden Weight Gain or Loss With TNF-alpha Inhibitors

In rare cases, TNF-alpha inhibitor drugs may cause sudden weight gain, swelling, breathing problems, or other symptoms linked to heart failure. Let your doctor know right away if you notice any of these symptoms.

Very rarely, these medications may also lead to an increased risk of certain types of blood cancer, such as leukemia or lymphoma. These cancers can cause sudden, unexplained weight loss. Other signs of these conditions include easy bruising or bleeding, tiredness, and swollen lymph nodes (hard lumps in the armpits, neck, or groin).

Interleukin Inhibitors

Interleukins are small proteins that help control how the immune system works and how inflammation forms. In people with RA, blocking these proteins with interleukin inhibitors can reduce damage and improve symptoms.

We don’t know much yet about how interleukin inhibitors affect weight. One small study looked at 21 people with RA who took an interleukin inhibitor called tocilizumab. On average, participants gained about 4.2 pounds. But the weight gain wasn’t from fat — it came from muscle gain.

Do Any Biologics Cause Weight Loss?

Some biologics might cause weight loss, but this weight loss is usually linked to serious infections, nausea, and loss of appetite. In rare cases, weight loss may be related to cancer. Tell your doctor right away if you have signs of infection, such as:

• Fever
• Chills
• Shortness of breath
• Sore throat
• Coughing
• Stiff neck
• Painful urination, or increased amounts of urine
• Diarrhea or vomiting

Other Common Causes of Weight Gain With Rheumatoid Arthritis

For people living with RA, weight changes may also happen for many reasons. In a large study of women with RA, those who gained a significant amount of weight early in the disease were more likely to:

• Be younger
• Get less physical activity
• Eat a less healthy diet
• Have a history of smoking
• Live with other chronic health conditions

These factors were associated with weight gain but did not necessarily cause it.

Weight changes can also happen with RA treatments other than biologics. Some people report gaining weight while taking corticosteroids like prednisone. Talk to your doctor if you’re concerned about changes in weight or how your treatment may be affecting your body.

How To Manage Weight Changes From Biologics

If you experience unwated weight changes while taking a biologic medication for RA, there are things you can do. Talk with your doctor before making any big lifestyle changes. Together, you can come up with a plan that works for your health and treatment goals.

Eat a Balanced Diet

Try to add more fruits, vegetables, and whole grains to your diet. Cut back on saturated fats, salty foods, and highly processed snacks. A healthy diet can help you lose weight and reduce pressure on your joints, which may ease RA symptoms.

Ask your doctor if you should talk to a dietitian. They can help you with meal ideas and healthy food choices for RA.

Get More Physical Activity

Gentle exercises can help you stay strong and manage your weight. Try stretching, walking, swimming, yoga, or tai chi. Strength-building exercises can also help.

Make sure your doctor says it’s safe before starting a new workout routine. Don’t push yourself too hard — go at your own pace.

Talk to Your Doctor About Any Concerns

Let your doctor know right away if you lose or gain weight and don’t know why. In rare cases, weight changes can be a sign of something more serious, like certain types of cancer, so it’s important to get checked.

Don’t Worry About Small Weight Changes

A little weight gain is normal and expected. Healthy adults gain an average of 1.1 to 2.2 pounds a year.

Additionally, some research has shown that gaining a little weight after starting a biologic may mean your treatment is working and your RA is improving.

Remember, not all weight changes mean something is wrong. But if you’re worried about how a biologic is affecting your body, talk to a healthcare professional.

Talk With Others Who Understand

On myRAteam, the social network for people with rheumatoid arthritis and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with rheumatoid arthritis.

Have you noticed weight changes while taking a biologic for your RA? Share your story in the comments below — or start a conversation by posting on your Activities page.