Is A Thyroid Problem The Reason For Your Weight Gain?

At this point, you’ve probably heard somewhere that thyroid issues can trigger weight gain or make it nearly impossible to lose weight. If you’ve been struggling to stabilize, it might be time to talk to your doctor about thyroid function—but when? Does your weight gain qualify as thyroid-concerning?

First, before we dive into symptoms, you might be wondering: What is the thyroid, and what exactly does it do? “The thyroid is a gland in the lower part of the neck that produces thyroid hormone,” says Nevin Ajluni, MD, an endocrinologist and diabetes expert at Michigan Medicine. “Thyroid hormone has many functions, but one of its functions does affect metabolism and all other tissues of the body. The thyroid regulates the energy balance in the body.”

There are actually two major forms of thyroid dysfunction, each of which has a separate (almost opposite) set of symptoms. Here’s what to know about each.


An underactive thyroid or hypothyroidism is when your thyroid is not producing enough thyroid hormone to help your body use energy effectively. This can occur due to an autoimmune disease like Hashimoto’s, a condition called thyroiditis that causes inflammation of the thyroid, or radiation treatment, among other causes. 

Weight gain is a common symptom, although Ajluni says it’s usually “modest.” Depending on your size and the severity of the issue, it could be five to 10 pounds or a real struggle to lose weight. Often, this is the result of fluid retention, or swelling in different regions of the body, which can lead to weight gain. “Typically someone with hypothyroidism would have more than weight gain as a symptom,” says Ajluni. 

Other symptoms include “fatigue, cold intolerance, decreased concentration, memory loss, foggy thinking, and constipation,” says Ajluni. She also says it’s common to have brittle nails, dry skin, and hair becoming more coarse. “People also complain about muscle aches and weakness, and sometimes have a depressed mood,” says Ajluni. Physically, you might also actually see enlargement of the thyroid, also known as a goiter. 


Opposite to that, people with hyperthyroidism would have too much thyroid hormone, thus speeding up the body’s normal metabolic rate. Common causes of hyperthyroidism include autoimmune conditions like Graves’ disease, in which antibodies stimulate hormone production, as well as toxic multinodular goiter, where benign lumps cause the thyroid to grow in size. “People often feel hot or get sweats,” says Ajluni. “They can have more frequent bowel movements, and there can sometimes be hair loss with hyperthyroidism. They may have an increased heart rate or feel more anxious.” It is also common to have “tremors” you can feel if your condition is more severe. 

Weight loss may also happen, since the metabolism is on overdrive, and it may be more noticeable than with hypothyroidism. “You can get significant weight loss if the overactive thyroid severe, and person cannot explain it,” says Ajluni. “They have not been exercising or dieting significantly, for instance. If you have weight changes, combined with other symptoms, it’s a good idea to get checked.”

When to Get Help 

If you notice multiple symptoms of hypo or hyperthyroidism, including weight loss or gain, talk to your doctor. Levels of thyroid hormone are not routinely checked, says Ajluni, so definitely bring it up at your next physical if you have any concerns—or sooner, if you have a strong inkling you need your thyroid checked out, or you have a family history of thyroid issues.

For hypothyroidism, the key is “replacing the missing hormone” by way of a drug called levothyroxine. “We will adjust the dose based on a person’s response to the hormone, and check using blood test—in fact, the same blood test we use to screen for thyroid issues,” says Ajluni. “Treatment for hyperthyroidism is different, and really depends on the underlying cause.”

Some treatments include radioactive iodine to shrink the thyroid gland, and antithyroid medications, which slow the thyroid’s hormone production. Beta-blockers can also help with symptoms like tremors and rapid heart rate, which might be bothersome. In rare cases, as in pregnancy where other treatments may be more challenging, surgery to remove part of the thyroid can also be discussed with your doctor.  

It’s important to keep in mind: With thyroid, even if you are gaining weight or not able to optimally control your weight, it’s not your fault at all.  “In most cases when there is thyroid dysfunction, it is often autoimmune or a viral illness,” Ajluni says, noting there’s very little you can do to prevent over- or underactive thyroid, other than being mindful of symptoms.

It’s important to maintain a balanced diet for the health of the thyroid, Ajluni says, but avoid trying to treat any suspected problems on your own. “Sometimes we can get into trouble when taking thyroid supplements with high doses or iodine,” she says, warning that it’s not the answer. What is the answer? Calling your doctor if you think your thyroid might be playing a role in uncomfortable symptoms, weight gain, or weight loss.

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