Hyperthyroidism causes the body to use up more energy than it typically would, which can lead to weight loss. Treatment can help people regain their lost weight.

The thyroid gland functions to produce the thyroid hormones thyroxine (T4) and triiodothyronine (T3). It then releases them into the bloodstream. In hyperthyroidism, the thyroid gland produces too many thyroid hormones.

This article examines hyperthyroidism and weight loss. It will explain how hyperthyroidism can cause weight loss, the effects of treatment, and whether people can use thyroid hormones for weight loss.

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One of the main symptoms of hyperthyroidism is weight loss without trying. This can sometimes happen despite increased appetite. Scientists know that many hyperthyroidism symptoms arise due to an increase in a person’s metabolism.

Metabolic activity involves both creating tissues while storing energy, and destroying tissues while using up energy. In hyperthyroidism, the overproduction of T4 and T3 encourages the latter kinds of processes.

A study in the International Journal of General Medicine explains that hyperthyroidism can induce the following:

  • an increase in calorie burning for basic bodily functions
  • an increase in bodily heat production
  • an increase in overall energy use

These increases frequently result in weight loss.

There are several ways to treat hyperthyroidism. First, doctors recommend ways a person can manage their symptoms. Then they look for ways to cure the underlying cause of hyperthyroidism.

An endocrinologist — a doctor specializing in hormonal conditions may recommend the following treatments:

Doctors will recommend a specific treatment plan depending on the underlying cause of hyperthyroidism.

There is good evidence that treatment can positively impact hyperthyroidism-induced weight loss.

Research shows that treatment can cause thyroid activity to return to normal levels. When this occurs, individuals usually regain the weight that hyperthyroidism caused them to lose.

However, a 2020 study in Clinical Thyroidology found that people having treatment for hyperthyroidism may put on more weight than they originally lost.

Researchers tracked the weight of 1,373 people who either took anti-thyroid medication, received RAI therapy, or had a combination of the two.

They found that, after treatment, males were 1.7 times more likely to develop obesity than people in a comparison group without thyroid disease. Females were 1.3 times more likely.

Most weight gain occurred in the first 6 months of treatment but continued until 24 months.

The researchers noted that the risk of weight gain can be worrying, but people must seek treatment for hyperthyroidism to avoid complications.

The treatment plan for hyperthyroidism must include strategies to prevent weight gain, and people can discuss these with a doctor.

Thyroid hormones are a treatment for hypothyroidism, a condition where the thyroid gland is underactive and does not produce enough thyroid hormone.

Taking thyroid hormones increases the body’s metabolism and may cause weight loss. However, these hormones should not be taken by people wanting to lose weight unless a doctor prescribes them to treat hypothyroidism.

Certain over-the-counter (OTC) weight loss supplements contain thyroid hormones of varying potency. It is unsafe to take these supplements. Excess thyroid hormones may lead to hyperthyroidism and cause symptoms such as rapid heart rate, heat intolerance, and anxiety.

Learn more about taking thyroid medication for weight loss here.

If an individual notices symptoms of hyperthyroidism, they should consult a doctor. An important symptom is experiencing significant weight loss despite having an increased appetite.

People may wish to note their symptoms before talking with a doctor. Doctors will likely recommend thyroid tests if they suspect a problem with the thyroid.

Learn whether Medicare covers thryoid tests here.

What will happen if hyperthyroidism is not treated?

There are several complications of untreated hyperthyroidism.

Untreated hyperthyroidism can cause thyroid storm, which is a life threatening condition. Research also shows that cardiovascular disease is another possible complication.

What counts as rapid weight loss?

Researchers define rapid weight loss as losing at least 5% of body weight within 5 weeks.

Weight loss is a common symptom of hyperthyroidism. An overactive thyroid produces too much thyroid hormone, speeding up metabolism and the rate at which it uses energy.

Treatment commonly includes medications and RAI. Some people may need thyroid surgery. With treatment, people usually regain the weight they lost. There is a possibility that people having treatment for hyperthyroidism may put on excess weight, so strategies to prevent this need to feature in treatment plans.

Taking thyroid hormones to lose weight is unsafe. People should avoid weight loss supplements containing thyroid hormones.

If someone experiences weight loss without trying or other symptoms of hyperthyroidism, they should contact a doctor.