The butterfly shaped endocrine gland that is located in the lower front of the neck is called the thyroid gland. The thyroid hormone is made by the thyroid gland which is secreted into the blood and carried to other tissues of the body. Thyroid hormone helps the body to use energy and normal functioning of the brain, heart, muscles and other organs. There is a complex relationship between body weight, thyroid disease and metabolism.

How does thyroid function affect weight?

The metabolism is regulated by thyroid hormone. Basal metabolic rate is the minimum amount of energy needed by the body to perform bodily functions. One of the earliest methods used for assessing a thyroid patient is basal metabolic rate. A low BMR is found in the patients with underactive thyroid and patients with overactive thyroid have high BMR. Patients with hyperthyroidism have high BMR and may experience weight loss. For example, if a person has an overactive thyroid, his/her BMR increases which leads to higher calories needed to maintain the body’s metabolism. If the person does not meet the calorie requirement needed to match the calories expended, then they may experience weight loss.

Thyroid hormone controls appetite, metabolism, and activity. Weight loss is observed more in hyperthyroidism and other conditions such as thyroiditis and in high dosage. Increased appetite is also seen in hyperthyroidism. Not only do patients lose weight but they may also gain weight depending upon the calorie intake.

The majority of patients with hyperthyroidism lose weight. Although the condition has varying effects and 10% of patients gain weight. While weight loss is the common side effect of hyperthyroidism, there are some situations where weight gain is possible.
 

Factors causing weight gain in people with overactive thyroid

Weight gain is more common in people with hyperthyroidism. The following factors may cause this to happen, 

• Increased appetite – Increased appetite is usually seen in hyperthyroidism. If the patient is having a high calorie diet, it can cause weight gain even though the body is burning more calories. It is important to maintain a balanced and nutritious diet, engage in regular exercise, and consult a dietitian for guidance. 
  
  

• Medications for overactive thyroid – Elevated levels of thyroid hormone is known as hyperthyroidism. Your body may return to its usual state after treatment. When you lose weight as a result of hyperthyroidism, you may regain some weight once you start taking medications. 
  
  

• Thyroiditis – An inflammation of the thyroid is known as thyroiditis. Thyroid hormone levels may be too high or low as a result of thyroiditis. Hashimoto’s disease is the most common type of thyroiditis and it may be the cause of hypothyroidism. 

How does food impact hyperthyroidism?

The food you eat may have an impact on your thyroid condition, including how well your thyroid medication is absorbed. To balance your thyroid hormones, you need to eat a variety of minerals, vitamins, and nutrients and include iron, selenium, and B vitamins rich foods. Iodine and selenium are the minerals that principally control thyroid function along with the support of vitamins A, E, D, and B. For a healthy thyroid, other micronutrients like zinc, copper, and iron are crucial. 

Consuming too many dietary supplements containing these vitamins and minerals can also be harmful to your health. For example, iodine promotes autoimmune antibodies. Supplementing with iodine may be linked to flare-ups of Hashimoto’s disease.

Adding or removing particular foods from your diet can help balance your thyroid hormones and manage your hyperthyroidism symptoms, even though diet alone cannot treat hyperthyroidism. 

Some foods may interact with medications like thyroxine. There are some nutrients and essential minerals that may support your thyroid function, 

• Iron 
• Selenium
• Iodine
• Vitamin D and calcium 
• Magnesium
  
  While there is no known cure for hyperthyroidism, some nutrients and minerals can help manage the underlying illness. The thyroid’s hormone production and function can be impacted by diet.
  
  

Iodine

• The thyroid gland produces too much thyroid hormone when exposed to too much iodine, which worsens hyperthyroidism.
  
  
• When a person has hyperthyroidism, they should limit their intake of foods high in iodine such as iodine supplements, fish, and iodised salt. Kelp causes thyroid issues in some people. 
  
  

Selenium 

• Due to its antioxidant properties, selenium is also important for the thyroid, as it helps protect against autoimmune thyroiditis. A major portion of selenium in the body is stored in the thyroid gland. It helps convert T4 to T3 hormone. It is found in Brazil nuts, seafood, poultry and meat, but amounts can vary depending on the selenium content.
  
  

 Iron

• The micronutrient iron is necessary for many bodily functions, including the health of the thyroid. Red blood cells need iron to help them carry oxygen to other parts of the body. 
  
  

Vitamin D and calcium  

• Low vitamin D and calcium are associated with hyperthyroidism and decreased bone mineral density. It may lead to osteoporosis. Vitamin D is found in fortified foods such as dairy products, eggs or plant-based milk, but sunshine (or supplements) is the best way to get enough. Vitamin D rich foods are also high in iodine. Most patients with hypothyroidism have vitamin D deficiency.
  
  

Magnesium 

• Having enough magnesium can help reduce the autoimmune attack on the thyroid gland by lowering the production of thyroid antibodies. Getting enough magnesium from food or supplements can help control autoimmune thyroid conditions and enhance thyroid function.
  
  

Conclusion

When your thyroid gland generates too much thyroid hormone, it is known as hyperthyroidism. When the calorie intake is more, the production of thyroid hormone increases leading to weight gain. Although treating hyperthyroidism is necessary to help prevent major side effects such an irregular heartbeat, which usually results in weight gain. Discuss with your doctor for the best course of action to manage your thyroid issue in order to maintain a weight that is appropriate for you.


Nesha Felciya,
Clinical Dietitian, Simplyweight