Can Hypothyroidism Make You Gain Weight?

If you’ve recently gained weight and you’re not sure why, an underactive thyroid might be the cause. Your thyroid gland and thyroid hormones play important roles in regulating your metabolism and weight. Here’s how.

What is hypothyroidism?

Hypothyroidism affects up to 5% of people, but probably more people have it without realizing it. In this common condition, the thyroid gland doesn’t produce enough thyroid hormones. The body needs thyroid hormones to maintain different systems, including a normal weight and a healthy metabolism. 

Hypothyroidism is much more common in women. And it’s particularly common during and after pregnancy and menopause. 

The most common cause of hypothyroidism is Hashimoto’s thyroiditis. This is an autoimmune condition where immune cells attack the thyroid gland, keeping it from working well. 

Does hypothyroidism cause weight gain?

Yes, often hypothyroidism causes weight gain. If you’ve recently gained weight without explanation, consider talking with your primary care provider and checking your blood thyroid hormone levels.

There’s no clear data on how much weight people gain with hypothyroidism or how much weight they lose after treatment. Estimates suggest that half of people with hypothyroidism experience some weight gain. And most people usually gain 5 to 10 pounds. But some women can gain more — especially if their thyroid hormone levels are very low for a long period of time. 

The cause of most weight gain in hypothyroidism is increased retention (holding onto) salt and water. But some weight gain can be from increased fat due to a slower metabolism.

Even though weight gain is a common symptom of an underactive thyroid, something else may be at play. This may be especially true if you’ve gained more than 10 pounds. Beyond checking your thyroid health, take a look at your stress levels, diet, sleep patterns, and physical activity.

How does hypothyroidism affect weight?

Researchers don’t know exactly how low thyroid levels cause weight gain. But it likely involves several processes:

• Slowing of your metabolism: Your thyroid helps control your metabolism. When thyroid levels are low, your metabolism slows down and you burn less energy, even when you’re resting. You’re also less likely to burn fat for energy, which can cause weight gain.

• Changes in appetite: Your thyroid regulates your appetite. It may lead to food cravings, increased appetite, and an increase in calories. 

• Fluid retention: Hypothyroidism may increase how much salt and water your body holds onto (retains), and this can lead to an increase in weight.

• Decreased physical activity: About 4 in 10 people with an underactive thyroid feel more tired than normal. This may lead to less physical activity, which can contribute to weight gain.

Will a thyroid medication help you lose weight?

Treating your low thyroid can help you from gaining more weight. But it may not help you lose the weight you’ve already gained. Other factors may be contributing, such as hormonal changes, poor sleep and nutrition, and low levels of physical activity. 

Treating hypothyroidism means taking a thyroid-replacement medication like levothyroxine (Synthroid). The amount you take can change depending on your blood work and symptoms, so it may take a few months to find the right dose for you. If you’re still having difficulty losing the extra weight, you may need to make other diet and lifestyle changes (more on those below).    

Can you lose weight when you have hypothyroidism?

In addition to treating hypothyroidism, there are ways to lose weight that you may have gained with hypothyroidism. Strategies include making healthy and sustainable changes to what and how you eat and drink as well as how often you’re physically active. There’s no specific diet or food that will reverse hypothyroidism. 

But let’s review some tips that will help you lose weight with hypothyroidism and maximize your thyroid health.

Cut out sugars and refined carbohydrates

Studies show that eating a diet of low-glycemic foods — those that are least likely to spike your blood sugar — help with weight loss. Examples of low-glycemic foods include nonstarchy vegetables, beans, whole grains, berries, fish, and meat. It’s also a good idea to avoid processed food as much as possible.

Focus on nutrient-dense whole foods 

It’s important to get the recommended amounts of vitamins and minerals in your diet. Making sure you have enough healthy nutrients in your diet can also contribute to a healthy thyroid. Low levels of iodine can also contribute to hypothyroidism, so be sure to use iodine-enriched salt (most table salts) and iodine-rich food like cod and yogurt. 

Studies have also shown that zinc and selenium can help improve hypothyroidism. And improving thyroid function may help restore your metabolism and ideal weight.

Check your fasting blood sugar (glucose)

Hypothyroidism has been linked to metabolic syndrome — a group of health conditions that increase your risk for diabetes and heart disease. It includes high blood sugar (diabetes), high blood pressure, abnormal fat and cholesterol levels, and a larger waist circumference. 

Because of this, it’s worth bearing in mind that extra weight may also be a sign of something else — not just hypothyroidism. So, if you have hypothyroidism and you’re having a hard time losing weight, talk with your primary care provider about screening tests for diabetes (or prediabetes) and these other health conditions. 

Get plenty of sleep and exercise 

It’s very clear that not getting enough regular and good quality sleep is linked with weight gain. It can also keep you from losing excess weight. The American Academy of Sleep Medicine recommends at least 7 hours of sleep each night and keeping a consistent sleep schedule.

Exercise is important for mental and physical health, and not getting enough can affect your ability to sleep well and keep excess weight off. The CDC recommends at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous aerobic activity each week.

Watch how much alcohol you drink

Alcohol can add a lot of calories to your diet. For some people, drinking too much is associated with weight gain. Cutting back how much you drink is often a good way to help lose weight. It will improve your sleep quality and energy levels, too. 

Try eliminating gluten

Autoimmune hypothyroidism has been linked with celiac disease, another autoimmune condition in which the immune system reacts abnormally to gluten. Gluten is a protein found in many different grains, including wheat. A gluten-free diet may help improve hypothyroid symptoms in some women, and it may help with weight loss. 

Gluten is in many foods, like:

• Bread products, including things like bagels and English muffins

• Traditional pastas, doughs, and crusts

• Crackers and cookies

Why trust our experts?

Written by:

Maria Robinson, MD, MBA

Maria Robinson, MD, MBA, is a board-certified dermatologist and dermatopathologist who has practiced dermatology and dermatopathology for over 10 years across private practice, academic, and telehealth settings. She is a fellow of the American Academy of Dermatology and the American Society of Dermatopathology.

Edited by:

Alex Eastman, PhD, RN

Alex Eastman, PhD, RN, is a California-based registered nurse and staff medical editor at GoodRx, where he focuses on clinical updates and Latino health.

Reviewed by:

Christina Palmer, MD

Christina Palmer, MD, is a board-certified family physician with a focus on chronic care management, women’s health, and mental health. She’s the co-author of “Open Heart: When Open-Heart Surgery Becomes Your Best Option.”.

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