Rheumatoid arthritis (RA) is a type of inflammatory arthritis — an autoimmune disease that affects the joints and can have negative effects throughout the body. Obesity is a known risk factor for developing RA. Research has shown that having increased body fat can also make certain RA medications less effective.

Body fat is actively involved in inflammation. Healthy levels of body fat help fight inflammation. Obese fat cells produce cytokines — chemical messengers that promote inflammation. The proinflammatory actions of excess body fat contribute to the development of RA, worse disease activity, and poorer RA outcomes.

A healthy body weight is an important part of your overall health, especially if you have RA. For some people, losing weight may help make their RA medications more effective.

How Does Body Weight Affect RA Treatment Outcomes?

Everyone is different, but one useful method for estimating your healthy body weight is body mass index (BMI). BMI is used as a screening test based on your height and weight:

• BMI less than 18.5 — Underweight
• BMI 18.5 to 24.9 — Normal or healthy weight
• BMI 25.0 to 29.9 — Overweight
• BMI 30.0 or higher — Obese

Obesity has a significant impact on how well people with RA respond to treatment. Research has shown that people with early RA who were overweight or obese were less likely to achieve remission within three years compared to people with a healthy BMI receiving the same treatment. Another study found similar results, showing worse treatment outcomes over two years in people with early RA who were obese compared with overweight and healthy-weight individuals.

However, people with RA may need to lose weight even if their BMI appears healthy. Chronic inflammation from RA can result in the loss of lean body mass and increased body fat. According to researchers, people with RA should be considered overweight with a BMI of 23 and obese with a BMI of 28, especially when it comes to assessing the risk of heart disease.

RA Treatments and Obesity

Treatments for RA can include nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and disease-modifying antirheumatic drugs (DMARDs).

DMARDs help control symptoms, prevent flare-ups, slow disease progression, and prevent joint damage. DMARDs can be broken down into two general types of drugs:

• Conventional DMARDs — These include methotrexate, Arava (leflunomide), and Azulfidine (sulfasalazine).
• Biologic DMARDs — Examples include monoclonal antibodies and other biological molecules.

Some research has shown that having a higher BMI may reduce how well conventional DMARDs work, but this only seems to be the case in people with established RA, not early RA. However, being overweight or obese may drastically reduce the effectiveness of some biologic DMARDs.

Biologic DMARDs and Obesity

Several types of biologic DMARDs used to treat RA target different aspects of inflammation. Some drugs target specific proinflammatory cytokines. For example, tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), IL-6, and others target immune cells (T cells or B cells) or enzymes needed to produce cytokines.

Biologic agents that target TNF-alpha, sometimes called anti-TNF drugs or TNF inhibitors, are used to treat several inflammatory diseases. Research has found that obesity significantly reduces the effectiveness of anti-TNF drugs in people with rheumatic diseases, including RA, spondyloarthritis, and psoriasis.

Other research has found drugs that target specific proinflammatory cytokines (including TNF-alpha and IL-6) are less effective in obese people with RA, both in terms of improving arthritis symptoms and reducing inflammation. The effect of obesity on these medications was seen more in women than in men, except with one drug, Actemra (tocilizumab), which was even less effective in men.

This same research found other biologics that work by acting on immune cells were not affected by obesity.

What RA Medications Are Most Affected by Excess Body Fat?

Several drugs tend to be less effective for treating RA in individuals with obesity:

• Actemra
• Cimzia (certolizumab)
• Enbrel (etanercept)
• Humira (adalimumab)
• Remicade (infliximab)
• Simponi (golimumab)

Other biologic DMARDs target similar cytokines that may not be affected by obesity in the same way. Kevzara (sarilumab), an IL-6 inhibitor, does not appear to be less effective in obese individuals with RA, nor does Kineret (anakinra), an IL-1 inhibitor.

Should You Lose Weight If You Have RA?

If you have excess body fat, or if you are overweight or obese, weight loss may help control your RA by reducing pain and inflammation, making certain medications more effective, and allowing you to do more physical activity.

Remember: BMI is only a screening test to show you whether you may have too much body fat. Talk to your doctor or health care provider about what your weight loss goals should be, if any, and how to reach those goals safely through appropriate diet and exercise.

There are many things in life that we have little to no control over, but maintaining a healthy body weight and healthy body fat composition are usually within your control. Research has shown that losing just 10 pounds by eating fewer calories, walking, and getting exercise a few days a week can significantly improve your body fat percentage and ability to exercise with RA.

Losing weight is not always easy, but knowing that it can improve your joint pain and day-to-day function can be motivating. To lose weight and become healthier, you may want to:

• Eat better
• Avoid certain foods
• Be more active

For some people who need dramatic weight loss, bariatric surgery can bring significant improvement for people with RA.

Talk With Others Who Understand

On myRAteam, the social network for people with rheumatoid arthritis, more than 176,000 members come together to ask questions, give advice, and share their stories with others who understand life with RA.

Do you think your weight affects your RA medication? Share your thoughts in the comments below, or start a conversation by posting on your Activities page.