You haven’t intentionally changed your diet or started a new exercise routine, yet your pants are getting looser and the number on the scale keeps going down. Should you celebrate — or start to worry?
While unexplained weight loss might seem like a welcome surprise (especially if you’re among the two out of three Americans who are overweight or obese), it’s often a red flag. Any number of conditions could turn out to be responsible for your unexplained weight loss: overactive thyroid, diabetes, cancer … the list goes on and on. And yes, rheumatoid arthritis (RA) is among the diseases that can cause weight loss.
To figure out what’s wrong, you and your doctor may need do some sleuthing, but weight loss probably won’t be your only clue. If RA is the culprit you’ll likely also have painful or swollen joints, fatigue, and trouble moving certain joints. Here are common symptoms of rheumatoid arthritis to be aware of.
Why Would Rheumatoid Arthritis Cause Weight Loss?
RA probably isn’t the first disease that comes to mind when you think of unexplained weight loss, but there are a few reasons why RA sometimes causes people to lose weight.
“Early on, when the disease is active, there’s a lot of inflammation, and [weight loss] can be a side effect of inflammation,” says Joshua Baker, MD, assistant professor of rheumatology and epidemiology at the University of Pennsylvania and Philadelphia VA Medical Center.
More specifically, the same cytokines (inflammatory proteins that are part of your immune system) that wreak havoc on the joints of people with RA also impact metabolism and contribute to the breakdown of muscle. That could happen if you have RA but haven’t yet been diagnosed; if you’ve been newly diagnosed and treatment hasn’t had a chance to kick in; or if you’ve been living with RA for a while but your current treatment has stopped working.
Another reason rheumatoid arthritis can cause weight loss is that it can decrease your appetite, says Caroline A. Andrew, MD, a medical weight management specialist at the Hospital for Special Surgery in New York City. Aches and pains can be a factor as well: “If a person has significant joint pain and cannot move easily or exercise, there may be a loss of muscle mass, causing weight loss,” she says.
What Happens to Your Weight When You Start RA Treatment?
Generally speaking, a newly diagnosed RA patient who was losing weight will start regaining weight once they begin treatment, because the medication will address the underlying inflammation that was responsible for the weight loss.
“If RA symptoms improve with treatment, a person can start to do physical therapy and exercise and start to regain muscle mass. Appetite may also improve,” says Dr. Andrews.
However, all drugs have side effects, including RA medications. Depending on what you take — and how your body reacts to it — you might experience weight gain or weight loss. According to one 2016 study, the drug leflunomide (Arava), one type of disease-modifying anti-rheumatic drug (DMARD) for rheumatoid arthritis, is more apt to cause weight loss as a side effect than some other RA medications. It sometimes causes diarrhea, nausea, and upset stomach, all of which can exacerbate weight loss.
No matter which RA drug regimen you’re on, be sure to talk to your doctor if you start losing weight for no apparent reason. That change is reason enough for your doctor to order some tests and reassess your disease activity. If your RA is no longer being well controlled, it may be time for change in your treatment plan.
Weight Loss and Comorbid Conditions
At the same time, Dr. Baker says your physician should screen you for other conditions that could be responsible for weight loss. “Are you having shortness of breath in addition to losing weight? If so, you might need a chest scan test for interstitial lung disease,” he says. This condition, in which scar tissue builds up in the lungs, is common among smokers, but Dr. Baker estimates that about 15 percent of RA patients also get it (including smokers and non-smokers). “We don’t fully understand why, but we think the same inflammation [that impacts the joints] is occurring in the lungs and causing damage,” he says. (Read more about how inflammatory arthritis affects the lungs.)
Whatever the reasons for your weight loss, it’s important to sort it out. RA patients who lose too much weight can become underweight and frail, which studies have shown increases the risk of early mortality.
The Other Side of the Coin: Rheumatoid Arthritis and Weight Gain
Clearly, unexplained weight loss with rheumatoid arthritis can be dangerous, but so is being overweight.
“Fat tissue releases cytokines, which cause inflammation in the body,” says Dr. Andrew. “These cytokine levels are already elevated when someone has an inflammatory arthritis, so being overweight can exacerbate the already existing inflammation.”
The physical toll of being overweight is also problematic. “Carrying extra weight places increased pressure and stress on the joints, which can worsen the pain and stiffness associated with rheumatoid arthritis,” says Dr. Andrew. “Every pound of excess weight places about four pounds of extra pressure on the knees.
The result of all that physical pressure, adds Dr. Baker, is that many people with RA also end up with osteoarthritis (the “wear-and-tear” kind of arthritis). That combo adds up to higher rates of disability and higher pain scores — and drug therapies can only help so much.
“Studies have shown that some DMARDs may not be as effective in subjects who are overweight or obese. One study showed that regardless of the type of initial treatment, subjects with RA who were overweight or obese were significantly less likely to achieve sustained remission compared to subjects with a normal weight,” says Dr. Andrew.
Meanwhile, you’re more apt to experience drug side effects if you’re overweight because obesity often causes inflammation in the liver that interferes with your ability to process drugs, says Dr. Baker. (Read more about how arthritis affects the liver.)
The upshot is that if you’re overweight and you can manage to lose even a small amount of weight, your arthritis prognosis should improve dramatically. “It’s OK if you don’t get to a ‘normal,’ weight,” says Dr. Baker. “That might not be possible or realistic.” Shedding just 10 percent of your current weight — that’s 18 pounds if you currently weigh 180 — could make a big difference.
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