If you have been noticing unexplained weight gain or even weight loss despite no change in your eating habits, it can sometimes be due to thyroid issues. The thyroid gland produces hormones that help regulate energy use, body temperature, and essential functions. If there is too much or too little thyroid hormone being produced, it can lead to changes in metabolism and weight.
However, there can be many reasons why there are changes in weight. Understanding how thyroid hormones can impact metabolism can help you to recognise the symptoms and seek medical advice at the correct time. At Molecular Diagnostics and Therapy, we offer diagnostic services. Dr Nikunj Jain (Co-Founder and Head of Nuclear Medicine) has vast experience in nuclear medicine and diagnostic imaging. Correct medical investigations can be carried out to determine the cause of unexplained weight changes.
How Does Thyroid Disease Affect Body Weight?
The main reason why thyroid disease can cause weight changes is down to how much thyroid hormone is produced.
Hypothyroidism is when the thyroid isn’t producing enough thyroid hormone. This can cause many functions in the body to slow down and can cause weight gain.
Hyperthyroidism is when the thyroid is producing too much hormone. This can speed up metabolism and cause weight loss.
However, everyone will be different in how much weight they gain or lose. Diet, exercise, medication, other medical issues, and appetite can all impact your weight. Why Does Hypothyroidism Cause Weight Gain?
Hypothyroidism can cause your body to use less energy. This can reduce how many calories you burn at rest and cause weight gain. However, weight gain with hypothyroidism will often be minimal. Some of the weight gain will be due to water and salt retention rather than actual fat gain. If you have significant weight gain, it shouldn’t be assumed it is due to a thyroid issue. Other symptoms of hypothyroidism can include:
Feeling tired even after adequate rest
Feeling unusually cold
Constipation
Dry skin or thinning hair
Difficulty concentrating
Low mood
Heavy or irregular menstrual periods
Common causes can include Hashimoto’s disease (an autoimmune disease that causes damage to the thyroid). Certain medications and previous thyroid treatments can also cause hypothyroidism. A blood test can be carried out to see if you have an underactive thyroid. Doctors will commonly test TSH levels. They may also test free T4 levels to understand how your thyroid is functioning. Why Does Hyperthyroidism Cause Weight Loss?
Hyperthyroidism can cause your body to use more energy. This can cause you to burn more calories than usual even at rest. This can cause unintentional weight loss. Some people will also have an increased appetite as their body is using more energy. If they aren’t eating enough calories, they can continue to lose weight. Common symptoms of hyperthyroidism include:
Weight loss despite a normal or increased appetite
Rapid or irregular heartbeat
Excessive sweating
Feeling unusually hot
Shaky hands
Anxiety or irritability
Difficulty sleeping
Frequent bowel movements
Muscle weakness
Can Weight Change After Thyroid Treatment?
Yes. When thyroid hormone levels are brought back into balance, there may be weight changes. Those with hypothyroidism may notice some weight loss as excess fluid is lost and hormone levels are balanced. However, this doesn’t guarantee significant weight loss, especially if there are other factors causing weight gain. Those with hyperthyroidism may also start to put on some weight as their metabolism comes back to normal. This is an expected change and doesn’t mean the treatment isn’t working. Always take thyroid medications as prescribed. Taking extra thyroid hormone to lose weight can cause issues with your heart rhythm, anxiety, muscle loss, and bone loss. How Is Thyroid Disease Diagnosed?
Doctors will look at your symptoms, medical history, and examination findings to decide what tests to carry out. Blood tests are commonly carried out first if a thyroid issue is suspected. A TSH test can be carried out to see if you may have too much or too little thyroid hormone. A free T4 test may also be carried out. If needed, thyroid antibodies and ultrasound can be carried out to look at specific thyroid issues. Nuclear medicine thyroid scans can be carried out in certain cases, for example, to look at specific thyroid nodules or to find out the cause of hyperthyroidism. However, they are not routinely carried out just because you’ve had weight changes. Dr Nikunj Jain (Co-Founder and Head of Nuclear Medicine) has experience in nuclear medicine and diagnostic imaging. The correct investigations will depend on the patient's symptoms and findings. Your treating doctor will decide what tests should be carried out. Conclusion
Weight changes can occur due to thyroid issues. Thyroid hormones can affect your metabolism. If you have an underactive thyroid, you may gain some weight. Whereas if you have an overactive thyroid, you may lose weight unintentionally. However, weight changes alone cannot confirm a thyroid issue. Correct medical investigations can help to identify thyroid issues. At Molecular Diagnostics and Therapy, we offer diagnostic services. Dr Nikunj Jain has experience in Nuclear Medicine and Diagnostic Imaging. If you are experiencing continual weight changes without knowing why, or other symptoms of thyroid issues, then please consult a qualified healthcare professional.