Since the BMR in the patient with hypothyroidism (see Hypothyroidism brochure) is decreased, an underactive thyroid is generally associated with some weight gain. The weight gain is often greater in those individuals with more severe hypothyroidism.

How much weight do you gain with hypothyroidism?

About half of people with hypothyroidism experience some weight gain. Most people usually gain only 5 to 10 pounds; however, some women can gain more, especially if the hypothyroidism is severe. While most of the weight gain is mainly increased salt and water retention, some of it can be due to increased fat gain.

Why do hypothyroid patients gain weight?

Most of the extra weight gained in hypothyroid individuals is due to excess accumulation of salt and water. Massive weight gain is rarely associated with hypothyroidism. In general, 5-10 pounds of body weight may be attributable to the thyroid, depending on the severity of the hypothyroidism.