Weight Gain and Hypothyroidism

Hypothyroidism is strongly associated with weight gain. In fact, weight gain is one of the most common symptoms of hypothyroidism—and is what ultimately leads many people to the diagnosis of thyroid disease.

Managing your weight can be a challenge with an underactive thyroid, which may be caused by Hashimoto's thyroiditis, medication side effects, a goiter, thyroid cancer, removal the thyroid gland, treatment of hyperthyroidism, iodine deficiency (though less likely in the United States), or a number of other conditions.

Ways to lose weight with hypothyroidism
Verywell / Laura Porter 

The Thyroid/Weight Gain Connection 

Hypothyroidism has long been associated with weight gain (and hyperthyroidism with weight loss), but the exact biochemical cause of this link is not completely clear. That said, there are several mechanisms that may explain the connection in cases of low thyroid function.

The two most active thyroid hormones, thyroxine (T4) and triiodothyronine (T3), circulate in the body, and they affect your metabolism through their interaction with your:

  • Fat cells
  • Muscle
  • Liver
  • Pancreas
  • Hypothalamus

Thyroid hormones normally help the body break down fat, and they help the liver and pancreas function to metabolize stored calories to be used for energy. These hormones also help the muscles throughout the body as they use energy. And when there is an adequate amount of thyroid hormones circulating in the body, the hypothalamus, which is a regulator of thyroid hormone in the brain, decreases the amount of thyrotropin regulating hormone (TRH) secretion.

All of these actions can be disrupted when you have decreased thyroid hormones or diminished thyroid function. Along with symptoms of low energy, the body also holds on to calories, storing them as fat, which is especially difficult to burn off and metabolize.

Treatment with thyroid replacement medications does not necessarily induce weight loss, even when optimal thyroid hormone levels are measured on blood tests.

Losing Weight With Hypothyroidism

If you have hypothyroidism, losing weight can be very challenging. Many people think that once you start taking thyroid hormone replacement medications, the weight just falls off. While treatment can help you lose some of the weight you have gained, it takes planning, hard work, diet, exercise, and getting enough sleep to shed a number of pounds.

Determining how far off you are from your ideal weight and body fat can help you assess how much weight you need to lose. A body mass index (BMI) calculator can help you get started.

Another step to weight loss is determining your own basal metabolic rate (BMR), which can help you gauge your metabolism and guide you in coming up with a target calorie intake per day.


An optimal diet minimizes simple carbohydrates and sugars and focuses on lean proteins and vegetables. A meal plan for hypothyroidism can keep you on track in terms of calorie goals.

If you are struggling to lose weight, consider working with a nutritionist to find a dietary plan that works best for you.


Exercise can also help you lose weight. Current guidelines from the Centers for Disease Control and Prevention (CDC) recommend that adults get 150 minutes of moderate exercise and two sessions of muscle-building each week.

However, people with hypothyroidism may need to go beyond these recommendations to lose weight.


Sleep deprivation is strongly linked to weight gain, and that association is clear whether you have thyroid disease or not. Getting enough restorative sleep on a regular basis can help prevent weight gain and help you keep weight off.

A Word From Verywell

If you have thyroid disease, you know that there are many symptoms. Mild to moderate weight gain is almost always part of living with hypothyroidism, and obesity, while less common, can be a problem as well. Usually, adequate thyroid treatment, as well as some lifestyle strategies, are needed to maintain a healthy weight—and to feel your best overall.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Chiovato L, Magri F, Carlé A. Hypothyroidism in Context: Where We've Been and Where We're GoingAdv Ther. 2019;36(Suppl 2):47–58. doi:10.1007/s12325-019-01080-8

  2. Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolismPhysiol Rev. 2014;94(2):355–382. doi:10.1152/physrev.00030.2013

  3. Peterson CM, Thomas DM, Blackburn GL, Heymsfield SB. Universal equation for estimating ideal body weight and body weight at any BMI [published correction appears in Am J Clin Nutr. 2017 Mar;105(3):772]. Am J Clin Nutr. 2016;103(5):1197–1203. doi:10.3945/ajcn.115.121178

  4. U.S. Department of Health and Human Services. Physical activity guidelines for Americans. 2nd ed.

  5. St-Onge MP, Shechter A. Sleep disturbances, body fat distribution, food intake and/or energy expenditure: pathophysiological aspectsHorm Mol Biol Clin Investig. 2014;17(1):29–37. doi:10.1515/hmbci-2013-0066

Additional Reading

By Mary Shomon
Mary Shomon is a writer and hormonal health and thyroid advocate. She is the author of "The Thyroid Diet Revolution."