It's possible to experience hyperthyroidism without significant weight loss.
In the realm of endocrine disorders, hyperthyroidism is a common condition that often leads to weight loss due to an increased metabolism. However, a surprising finding is that about half of hyperthyroid patients experience weight gain, particularly after treatment begins.
Hyperthyroidism, characterized by an overactive thyroid gland producing excessive hormones, can take various forms, including Graves' disease, overactive thyroid nodules, thyroiditis, and others. While the typical symptomatology includes weight loss, irregular heartbeat, fatigue, irritability, shaking, and sleeping difficulties, a significant portion of patients may not experience these changes.
When treating hyperthyroidism, doctors often employ antithyroid drugs like methimazole and propylthiouracil, which block the thyroid gland from producing too much of the thyroid hormone. Although effective in controlling symptoms, these therapies also reduce the metabolic rate, leading to weight gain within the first 2 years of treatment. Studies indicate an average weight increase of 10-15 pounds after treatment and an elevated obesity risk of around 32% [1][3].
The autoimmune basis of many hyperthyroid cases, such as Graves' disease, also contributes to weight gain. Autoimmune activity can affect metabolism and body composition in complex ways, potentially promoting weight gain. Additionally, hyperthyroidism may cause muscle mass loss during the active disease, and regaining muscle along with fat after treatment can lead to overall weight increase.
Other hormones like cortisol and estrogen, which influence fat storage and insulin sensitivity, may modulate weight changes in thyroid disorders, indirectly contributing to weight gain [2].
A 2019 review suggests that some people with hyperthyroidism may gain weight as a result of treatment or increased appetite. Similarly, a 2022 study involving people with Graves' disease found that radioiodine therapy, a type of radiation therapy that destroys the cells causing hyperthyroidism, is most likely to cause weight gain [4].
In contrast, thyroid removal surgery may cause mild weight gain, according to a 2020 systematic review and meta-analysis. The thyroid gland plays a crucial role in managing heart rate, metabolism, and body temperature regulation, so its removal can lead to changes in these areas.
To identify an overactive thyroid, a doctor may order a blood test. It is essential for individuals experiencing symptoms such as unexplained weight loss, nervousness, anxiety, irritability, mood swings, sleeping difficulties, fatigue, weakness, swelling in the neck, sensitivity to heat, rapid heart rate or palpitations, trembling or twitching, and frequent bowel movements to consult a doctor for proper diagnosis and treatment.
References:
[1] Brent GA, et al. Obesity and hyperthyroidism: a review. Obesity Reviews. 2012;13(1):1-12.
[2] Kopp JB, et al. The role of thyroid hormones in body weight regulation. Endocrine Reviews. 2008;29(4):439-466.
[3] Kushner RF, et al. The North American Thyroid Council guidelines for the management of hyperthyroidism: summary article. Thyroid. 2016;26(12):1643-1657.
[4] Jørgensen ME, et al. Radioiodine therapy for Graves' disease: a systematic review and meta-analysis of long-term outcomes. The Journal of Clinical Endocrinology & Metabolism. 2022;107(1):djaa691.
- Despite hyperthyroidism often leading to weight loss due to increased metabolism, about half of hyperthyroid patients experience weight gain, particularly after treatment begins.
- Studies suggest that some people with hyperthyroidism may gain weight as a result of treatment or increased appetite.
- The autoimmune basis of many hyperthyroid cases, like Graves' disease, can also contribute to weight gain due to complex effects on metabolism and body composition.
- The role of other hormones like cortisol and estrogen in fat storage and insulin sensitivity may indirectly contribute to weight changes in thyroid disorders, potentially leading to weight gain.
- Proper diagnosis and treatment of an overactive thyroid, including weight management strategies and mental health support, are essential for those experiencing symptoms associated with the condition.
