Losing weight can be a struggle when you have thyroid disease. Hypothyroidism (underactive thyroid) slows your metabolism, and, even with a healthy diet and exercise, you can still gain weight. But there are ways to counter this effect by not only knowing what to eat and what not to eat but also learning when and how to eat.

Routine exercise, ample hydration, medication adjustments, and improved sleep also factor into an effective weight-loss plan if you have thyroid disease.

This article explains how hypothyroidism causes weight gain and what you can do to better manage your weight with diet, exercise, and other healthy lifestyle choices.

Illustration by Paige McLaughlin for Verywell Health

The Thyroid Weight-Loss Problem

Even when you have mild hypothyroidism, your metabolism can slow significantly. This is because the thyroid hormones triiodothyronine (T3) and thyroxine (T4) are responsible for digestion and metabolism. The less T3 and T4 you have, the less able your body is to burn calories for fuel. Weight gain is the result.

Hypothyroidism can also make you feel tired, achy, and less likely to exercise, making it even more challenging to manage your weight. On top of this, when you are tired, you’re more likely to crave high-sugar foods for energy.

An imbalance in T3 and T4 also leads to a build-up of salt and water in your body which contributes to weight gain due to fluid retention.

Low T3 and T4 levels also have a knock-on effect causing the disruption of other hormones that influence metabolism and weight.

Among them:

  • Leptin and ghrelin are hormones influenced by T3 and T4 that regulate weight and appetite. Low levels of these hormones contribute to obesity and an inability to lose weight.
  • Insulin helps regulate glucose (sugar) in the body. Insulin resistance, common in people with hypothyroidism, leads to high blood sugar levels and increased fat stores.
  • Thyroid hormones also influence the stress hormone cortisol. High levels of cortisol can lead to overeating and weight gain.

Learn What to Eat If You Have Hypothyroidism

There is no “hypothyroidism diet” per se, but there certain eating rules that can help you lose or manage weight if you have low thyroid function.

Increase Your Fiber Intake

Eating more fiber-rich foods like beans, whole grains, and berries can have a number of health benefits for someone with hypothyroidism:

  • Fiber makes you feel fuller, faster: Because it takes longer to digest fiber, you need to eat less high-fiber foods in order to feel full. This can help you lose weight over the long term.
  • Fiber helps prevent constipation: Hypothyroidism slows down digestion, which can cause chronic constipation. Increasing your fiber intake can help keep your bowel movements regular.
  • Fiber helps lower cholesterol: People with hypothyroidism can have elevated cholesterol levels. A diet high in fiber can help combat this.
  • Fiber helps control blood sugar: Because it takes longer to digest high-fiber foods, the sugar in those foods takes longer to reach your bloodstream. This can help keep your blood sugar in control.

Eat More Fruits and Vegetables

Plant-based foods are an important part of any diet, but eating a diet rich in fruits and vegetables can be especially helpful for someone with hypothyroidism.

Vegetables are low in calories, so eating more of them can help you feel full without contributing to weight gain.

Moreover, studies have found that eating a diet high in fruits and vegetables and low in animal-based foods can help protect against cellular damage in people with hypothyroidism, slowing the progression of the disease.

Choose High-Quality Proteins

Diets low in protein can inhibit thyroid function. This can contribute to an underactive thyroid. Making sure you get enough protein can help combat hypothyroidism.

Protein can also help increase your metabolism and reduce hunger. This means good quality protein can help you burn calories and reduce the desire to overeat.

Eat Healthy Fats

It’s important to avoid unhealthy sources of fat like deep-fried foods and processed oils. On the other hand, healthy fats can be an important part of your diet if you have hypothyroidism.

Some healthy sources of fat include:

  • Cold water fish like salmon and tuna
  • Seeds like flax and chia
  • Nuts such as Brazil nuts and walnuts

Like fiber and protein, healthy fats can help you feel fuller for longer. They may also help control the hormones that make you feel hungry.

These foods also contain important nutrients. Brazil nuts, in particular, are high in selenium, which is essential for healthy thyroid function.

Eat More Whole Grains

Brown rice, wheat bread, popcorn, and other whole grains provide vitamins, minerals, and fiber that are vital for optimal health. Whole grains take longer to digest than simple carbohydrates like white rice and white bread, so they keep you fuller for longer.

Simple carbohydrates contribute many calories to your diet yet offer few nutrients. Be sure to consume them in moderation.

Avoid These Thyroid-Disrupting Foods

Some otherwise healthy foods can slow down your thyroid function and lead to weight gain. The culprits are compounds called goitrogens found in foods like:

  • Cruciferous vegetables (such as spinach, kale, cabbage, cauliflower, broccoli, turnips, and rapeseed)
  • Cassava
  • Lima beans
  • Linseed
  • Sorghum
  • Sweet potato
  • Soy
  • Millet

You can eat these foods in moderation, especially if they’re steamed or cooked. However, you should be careful not to eat large amounts.

Soy is a special concern. Along with containing goitrogens, soy can block your body’s absorption of thyroid drugs, making them less effective. This can pose a significant problem for someone following a strict vegetarian or vegan diet who relies on soy for protein.

7 Essential Facts About Goitrogens and Diet

Stay Well Hydrated

Proper hydration is essential to weight loss whether you have thyroid disease or not. Drinking enough water keeps your metabolism working efficiently. It can also help reduce your appetite, eliminate water retention and bloating, and improve elimination and digestion.

Although there is no hard-and-fast rule for how much plain water we should drink each day, the total amount of water recommended for healthy adults is 11.5 cups for people assigned female at birth and 15.5 cups for people assigned male at birth.

Around 20% of the fluid we take in comes from the foods we eat. Therefore, females would need around 9 cups of water or other fluids daily and males should have around 13 cups to meet daily fluid requirements.

Adjust When and How Much to Eat

The timing of meals and snacks—and how much you eat—are important factors for weight loss when you have thyroid disease.

Timing of Meals

Recent studies have shown that changing the timing of meals and the length of breaks between meals may help boost your metabolism and promote weight loss.

One approach is an intermittent fasting diet, which can be done in a couple of ways:

  • Restricted daily timeframe: Each day, you would only eat during a set period of between six hours and eight hours.
  • 5:2 approach: For this approach, you eat regularly for five days but for two days are limited to a single meal of between 500 and 600 calories.

Some people may have success with a grazing-all-day approach, which typically involves three small meals plus three snacks a day at regular intervals.

Check with your healthcare provider first before starting an intermittent fasting diet to make sure that it’s safe for you.

How Much You Eat

It is well established that weight loss is influenced by how many calories you eat and how many you burn each day. In general, the recommended calorie intake for adults is:

  • Between 1,600 and 2,400 calories per day for people assigned female at birth
  • Between 2,000 and 3,200 calories per day for people assigned male at birth

The actual calories you need depend largely on your age and level of physical activity. A healthcare provider or a nutritionist can help determine what’s best for you.

Eating too few calories is not a solution and may end up stalling weight loss. This is because your body goes into starvation mode and starts consuming muscle for energy instead of fat. Eating too few calories also deprives you of the nutrients you need to stay healthy.

How to Exercise to Lose Weight

Being physically active can support healthy thyroid function. It can also spur weight loss by boosting your metabolism, reducing fluid retention, and making you feel more energetic.

Studies suggest moderate- to high-intensity aerobic exercise can suppress your appetite by balancing appetite-regulating hormones.

To reap the health benefits of exercise, aim for moderate-intensity aerobic activity 30 minutes a day, five days a week. (You could also do 45 to 60 minutes a day, three days a week.) Aim to perform muscle-strengthening activities at least two days per week.

If you have not exercised in a long time, consider starting with 10-minute walks twice a week. Over time, you can increase your pace and duration.

Besides brisk walking, moderate-intensity aerobic exercises include water aerobics, cycling, tennis, raking the yard, and mowing the lawn.

Examples of muscle-strengthening exercises include weight lifting, resistance band training, body-weight exercises (such as push-ups and squats), and heavy yard work (like shoveling or digging).

Get Ample Sleep

One of the most important things you can do to boost weight loss is to get enough sleep. Numerous studies link sleep deprivation to a slowed metabolism and obesity. Not getting enough sleep may make you more vulnerable to developing heart disease or diabetes.

It is a good idea to get at least seven hours of sleep each night, especially if weight loss is a challenge.

If you have problems sleeping, there are things you can do to improve your sleep hygiene:

  • Be consistent with your bedtime each night.
  • Make sure your bedroom is quiet, dark, and at a comfortable temperature.
  • Remove electronic devices from the bedroom, like TVs, computers, and smartphones.
  • Avoid large meals, caffeine, and alcohol before bedtime.

Try Natural Supplements

Some supplements are thought to promote weight loss. Although these haven’t been extensively studied, they are generally safe for use when taken at the manufacturer’s recommended dose:

Be sure to check with your healthcare provider before using any supplement for weight loss. Some, like grapefruit, can interact with drugs like statins (use to treat high cholesterol) and anticoagulants (blood thinners), making them less effective.

Talk to Your Healthcare Provider

You may find it difficult—or even impossible—to lose weight if your hypothyroidism is untreated or undertreated. If you’ve tried diet and exercise without success, consider having your thyroid hormone levels tested to see if you are within the optimal testing range.

Oftentimes, low T3 levels translate to higher weight gain. By normalizing levels with the T3 replacement hormone Cytomel (liothyronine), you may be better able to manage your weight. For weight loss purposes, studies suggest this may be more effective than using the T4 replacement hormone Synthroid (levothyroxine) on its own.

Even so, it is possible to have weight problems when thyroid hormone tests show that you’re in the optimal range. In cases like this, a rational approach including diet and exercise is commonly advised along with an adjustment of other medications that may contribute to weight gain.

Time For a Medication Change?

Some medications prescribed for thyroid-related symptoms or other conditions can cause weight gain, including:

  • Antithyroid drugs: including Tapazole (methimazole) and PTU (propylthiouracil)
  • Beta-blockers: Including Sectral (acebutolol), Tenormin (atenolol), and Corgard (nadolol)
  • Corticosteroids: Including prednisone
  • Estrogen and progesterone: Either alone or together in hormonal birth control
  • Antidepressants: Including Prozac (fluoxetine), Paxil (paroxetine), and Zoloft (sertraline)
  • Mood-stabilizing and anticonvulsant drugs: Including lithium, Depakote (valproate), and Tegretol (carbamazepine)

If you’re taking any of these medications and you’re gaining weight, talk to your healthcare provider about your concerns. Never stop taking a medication without your healthcare provider’s input.

Additional Testing

Research shows that hormone resistance problems—including leptin resistance and insulin resistance—may contribute to the difficulties many thyroid patients face in losing weight. 

And since both hyperthyroidism (an overactive thyroid) and hypothyroidism are associated with insulin resistance, you should consider having your fasting glucose and insulin levels tested, evaluated, and treated.

Fasting glucose above 100 milligrams per deciliter (mg/dL) may be a sign of insulin resistance and prediabetes, which can make weight loss even more difficult.

For borderline levels, limiting added sugars, practicing mindful eating, and reducing your intake of foods high in refined carbohydrates, such as pastries, French, fries, and potato chips, can lower your blood sugar and help with weight loss.

Your healthcare provider may prescribe a type 2 diabetes drug like Glucophage (metformin) for chronically elevated levels.

Prescription Weight-Loss Drugs

There are several drugs prescribed for weight loss that can help, although they pose certain risks in people with thyroid disease and need to be used with caution:

  • Saxenda (liraglutide): This diabetes drug can promote weight loss. Even so, Synthroid can interact with Saxenda and make it less effective. Saxenda may also increase the risk of medullary thyroid cancer (MTC) and should be avoided if you have a personal or family history of MTC.
  • Wegovy (semaglutide): This is an injectable weight-loss drug for adults with obesity. Using it with Synthroid may increase blood sugar and increase the risk of type 2 diabetes. Wegovy can affect the absorption of Synthroid and possibly raise your T4 levels to dangerous levels.
  • Alli and Xenical (orlistat): Alli is the over-the-counter version of the weight loss drug Xenical. While both are useful for weight loss, they can reduce the absorption of Synthroid and make it less effective. Separating the dose by four hours can usually overcome this concern.
  • Zepbound (tirzepatide): This is an injectable weight loss medication for adults with obesity. Zepbound may interact with Synthroid and increase the risk of MTC. Those with a personal or family history of MTC should avoid it. Terzepatide is also the active ingredient in Mounjaro, which is approved to treat diabetes. 

The weight-loss drug Qsymia (phentermine/topiramate) isn’t generally recommended for anyone taking Synthroid or Cytomel. Taking Qsymia with either of these thyroid drugs can increase heart rate and blood pressure and increase the risk of heart disease.

Thyroid Disease Doctor Discussion Guide

Get our printable guide for your next doctor’s appointment to help you ask the right questions.

Doctor Discussion Guide Woman


Hypothyroidism slows your metabolism and makes other changes that can hamper weight loss. Other hormones that influence weight and appetite may be affected as well.

If you’re having trouble losing weight, ask your healthcare provider about testing your thyroid hormone levels. They can help determine if you need medication or a change in dosage.

You may be able to jumpstart your weight loss by getting enough sleep, staying hydrated, following a special diet, eating more fiber, avoiding goitrogens, and increasing your physical activity. Diet drugs may pose special problems for people with hypothyroidism because of drug interactions.


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