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How Long After Starting Thyroid Medication to Lose Weight?

Hypothyroidism may cause weight gain. Learn the explanation and the role of thyroid medication in weight loss.
How Long After Starting Thyroid Medication to Lose Weight?
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Hypothyroidism and weight gain often go hand in hand. Indeed, weight gain is one of the more common symptoms associated with an underactive thyroid. Understandably, many people assume that taking thyroid medication will help them lose weight. Some doctors even prescribe it to help with weight loss (which is a big no-no in the absence of thyroid disease.) Ahead, determine how much weight you can expect to lose once you start taking thyroid medication and if it is a sustainable solution.

The thyroid-weight connection

Your thyroid is the master of the body's metabolism. It helps regulate how fast you use and store energy, and it also controls growth and development. Thyroid hormones regulate everything from your heart rate and body temperature to your skin's moisture and hair growth.

Not surprisingly, thyroid hormone can play a significant role in weight. People who produce too much thyroid hormone (hyperthyroidism) have a faster metabolism, which generally makes it hard to gain weight. 

On the contrary, people with an underactive thyroid have a slower metabolism, making it harder to utilize and burn energy. Not only that, low thyroid hormone causes fatigue, sluggishness, and joint pain, which can take away your motivation to exercise.

One of the more surprising side effects of low thyroid hormone is a diminished appetite. Thus, while people with hypothyroidism often struggle with weight gain, the thyroid is usually not the only culprit behind increasing numbers on the scale. Indeed, most people can only attribute about ten added pounds to their thyroid condition. 

So, what is causing the pounds to add up aside from the thyroid? 

Likely, other causes of weight gain play a factor in what you see on the scale. These factors can include metabolic syndrome, stress, hormone fluctuations (for instance, menopause), heart disease, overeating, or heart disease. 

According to Dr. Ronald J. Koenig, M.D., as quoted in a news release for the American Thyroid Association, "Because obesity and hypothyroidism are very common, there are many patients who have both conditions. Patients often assume the hypothyroidism is causing obesity even though this may not be the case."

What you can expect when you start thyroid medication

Most people cannot expect extreme weight loss once they start thyroid hormone replacement medication. Again, this is because weight gain is often caused by other factors aside from an underactive thyroid. Generally, people begin to notice weight loss about three to six months after hitting a therapeutic dose of their medication. 

People lose about five to ten pounds on thyroid medication or less than 10% of their body weight. The weight loss is usually caused by the body getting rid of an excess accumulation of water and salt (i.e., water weight). Most research does not show that thyroid medications like Synthroid help you lose adipose (fatty) tissue. 

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Do doctors prescribe thyroid medication to help with weight loss?

In the past, some doctors prescribed thyroid medication to help people lose weight even if they did not have a thyroid condition. Of course, it seemed to make sense at the time: if you speed up the metabolism, you can expect to see more weight loss in less time. 

However, there is a big problem with this approach to weight loss. Too much thyroid hormone also causes other symptoms in your body—some of which may even cause you to gain weight. 

Generally, people with excess thyroid hormone have symptoms that can hinder weight loss, such as anxiety, insomnia, a rapid heart rate, muscle weakness, and heat sensitivity. Indeed, anxiety alone can often lead to overeating or comfort eating, adding to weight gain. Thus, excess thyroid hormones or taking a larger dose of thyroid medication is unlikely to lead to dramatic weight changes.

Suppose your thyroid-stimulating hormone (TSH) and T4 levels are borderline, or you have subclinical hypothyroidism. In that case, weight gain may be enough to support your doctor's decision to prescribe medication. If this is the case, you will want to watch for signs of hyperthyroidism and be diligent in having your thyroid levels assessed per your doctor's recommendation.

Additional tips for curbing weight gain with hypothyroidism

Treat your underactive thyroid

While treating hypothyroidism is likely not the only solution for helping you slim down to your ideal weight, it will help you get back on track. Normalizing your thyroid hormones usually improves your energy levels, reduces fatigue, decreases muscle and joint pains, relieves constipation, and improves low mood.

Skip the center aisles at the grocery store

Shopping around the perimeter of the grocery store is an excellent strategy for eating well because that is where you find fruits, vegetables, and meat. Center aisles usually contain the processed foods, which are often high in saturated fats and refined sugars, which can inhibit your weight loss efforts.

Find an exercise routine you can stick to

Daily exercise is necessary for everyone, especially in our sedentary, overly busy world. But, if you force yourself to run and you cannot stand running (or it hurts too badly), you likely will not stick with it. Do something that you find fun and enjoyable—maybe gardening, a pilates class with friends, or water aerobics.


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Consider the autoimmune protocol (AIP diet)

One of the leading causes of hypothyroidism is autoimmune thyroiditis or Hashimoto's thyroiditis. People with autoimmune diseases may benefit from trying the autoimmune protocol, a temporary elimination diet. The AIP diet helps you identify which foods may be causing inflammatory markers to wreak havoc on your system. 

Build a comprehensive care team

Working with your thyroid doctor, nutritionist, trainer, and even therapist can help you attack your weight gain from all angles. Excess weight is often a multifaceted, complex problem, and everyone has a unique profile that deserves individualized weight loss plans. 

A note from Paloma Health

Weight gain is a frustrating symptom of hypothyroidism. Meeting your weight loss goals with a thyroid condition often requires you to approach your weight from many angles. Schedule a consult with one of our board-certified thyroid doctors or thyroid nutritionists to help you get back on track.


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Julia Walker, RN, BSN

Clinical Nurse

Julia Walker, RN, BSN, is a clinical nurse specializing in helping patients with thyroid disorders. She holds a Bachelor of Science in Nursing from Regis University in Denver and a Bachelor of Arts in the History of Medicine from the University of Colorado-Boulder. She believes managing chronic illnesses requires a balance of medical interventions and lifestyle adjustments. Her background includes caring for patients in women’s health, critical care, pediatrics, allergy, and immunology.

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