If your workouts are suddenly feeling way harder than usual, there are lots of possible culprits. Maybe you’ve been super stressed and are sleeping poorly, or you haven’t been able to hit the sack for your usual seven hours. But if you’re suddenly unable to motivate yourself to hit the gym — much less get through workouts that once seemed like a breeze — hypothyroidism might be to blame.
RELATED: Always Tired? 12 Ways Wellness Experts Combat Exhaustion
What Is Hypothyroidism?
Your thyroid is a gland that lives at the base of your neck. It secretes hormones that control your metabolism, which is how your body uses energy.
When your thyroid stops producing enough of these metabolism-regulating hormones, hypothyroidism is likely to blame. This condition slows your body’s functions down, which results in you feeling fatigued and making your workouts feel harder. Some other symptoms include weight gain, shortness of breath when exercising, cold intolerance and muscle and joint pain.
Hypothyroidism is almost always caused by an autoimmune disorder called Hashimoto’s disease, says Elizabeth Pearce, M.D., an endocrinologist at Boston Medical Center specializing in thyroid disorders. With Hashimoto’s disease, the immune system attacks your thyroid, causing inflammation that may lead to thyroid failure.
So who’s most likely to get it? Hypothyroidism is most common in people with a family history. It’s also more prevalent in people who have other autoimmune disorders like type 1 diabetes, rheumatoid arthritis and lupus. While it can occur in both men and women, Pearce says hypothyroidism is about five times more common in women.
RELATED: 8 Signs You’re Way Too Stressed (and How to Deal)
Sneaky Hypothyroidism Symptoms
Hypothyroidism is notorious for flying under the radar. While it can show up suddenly, it can also develop gradually over months or even years. And because it shares symptoms like fatigue and weight gain with other conditions (anemia, depression and sleep apnea), many people have difficulty pinpointing it.
“One of the challenging issues of diagnosis of hypothyroidism is it affects the whole body and every organ. So you can have multiple symptoms that are not very specific,” says Pearce. “For every symptom it causes, there are maybe 10 to 1,000 other disorders that could be the cause.”
Pearce says that studies have shown that the more hypothyroidism symptoms people have, the more likely they are to have the condition. But 20 percent of people with hypothyroidism have no symptoms at all, while 50 percent of people with normal thyroid function report at least one symptom, she says.
The only way to know whether your thyroid is functioning properly is to get a blood test that measures thyroid-stimulating hormone. (TSH is a pituitary hormone that regulates your thyroid.) When your pituitary gland senses there’s not enough thyroid hormone being produced, it will produce more TSH to boost levels. Elevated levels of TSH will show up in a blood test even before your thyroid hormone levels drop, says Pearce.
RELATED: 7 Bedtime Rituals to Help Banish Your Insomnia
Hypothyroidism Treatment: What’s Next?
Before jumping to conclusions and self-diagnosing, remember this: Feelings of exhaustion or lethargy may be temporary.
“If you slept poorly for the past couple of nights or have been under a lot of stress, it’s probably short-term,” says Pearce. “But if it’s persistent, new and really different from your baseline, especially with other symptoms like cold intolerance and constipation, get tested. It’s cheap, easy and reliable.”
Once you’re diagnosed with hypothyroidism, your doctor will prescribe a medication that’s just like the hormones your thyroid makes. You’ll get regularly tested to be sure it’s doing its job. For most people, this medication completely controls hypothyroidism as long as you take it as directed, Pearce says.
It’s important to note that there’s no way to prevent hypothyroidism. “As of now, there’s no advice for your lifestyle, diet or exercise that will make any difference to your outcome,” says Pearce. “I recommend exercise as part of a healthy lifestyle to anyone, but there’s no evidence that it changes the course of the condition.”
RELATED: 6 Ways to Naturally Boost Your Metabolism
The Fine Print
While Pearce says that there’s no scientific proof that exercise can help relieve hypothyroid symptoms, there’s reason to think it could help.
“We know that exercise is good for depression. Even though they’re different conditions with different causes, they do have similar symptoms,” says Pearce. “So it seems to me that exercise might help with some hypothyroid symptoms.”
Just proceed with caution: “People who have been recently diagnosed with profound hypothyroidism should not push themselves too hard until their symptoms improve,” she says. Pearce recommends avoiding workouts that are too intense and that you can’t handle until your hypothyroidism is under control. But what’s right for you can vary. Every person is at a different fitness level, so if you’re already a regular runner or cyclist, there’s likely no reason you’d have to cut back.
Although no specific exercises have been shown to help improve symptoms, yoga can be a safe place for workout newbies to start. Compared to cardio classes like spinning or HIIT, you’re unlikely to push yourself too hard, says Pearce. Plus some research has shown that yoga can help boost energy levels, fight stress and reduce symptoms of depression.
RELATED: 5 Surprising Health Benefits of Yoga
Bottom line: Talk to your doctor about what workouts are right for you, and be kind to yourself. “Don’t exercise to the point of exhaustion. Listen to your body and limit the intensity until you’re feeling better,” says Pearce.