Title: The Link Between Thyroid Hormones and Weight
Headings: The Relationship Between Thyroid Hormones, Metabolism, and Weight
The Relationship Between Thyroid Hormones, Metabolism, and Weight
How the Thyroid Gland Works
The Role of Metabolism
The Role of Thyroid Hormones
Research
Hypothyroidism and Weight
Weight Loss With Treatment
The More Medication Myth
Hyperthyroidism and Weight
The Weight Loss Challenge
Low T3 Levels
Hormone Resistance
Leptin Resistance
Insulin Resistance
A Word From Verywell

Content: But a 2017 study examined 1,100 participants with normal thyroid function and found no link between changes in TSH and body mass index (BMI) after a follow-up period of 10 years. 4 ﻿ However, this study did find that patients with lower levels of free T4 tended to have higher BMIs. The variance in study results further illustrates how intricate the relationship between thyroid hormones and weight really is. The bottom line is that further research is needed. Hypothyroidism and Weight
As discussed above, the simplistic explanation is that having an underactive thyroid often causes people to gain weight because their bodies stop using calories efficiently. A lot of this weight is excess water and salt. Typically, the more severe the hypothyroidism, the greater the weight gain, but usually it's between five and 10 pounds. 5 ﻿
Somewhere between 10% and 60% of obese adults also have autoimmune hypothyroidism. 2 ﻿ Some studies have concluded that even mild hypothyroidism can lead to weight changes and may be a risk factor for weight gain and changes in BMI. Verywell / Emily Roberts
Weight Loss With Treatment
There aren't many scientific studies regarding how much weight is gained or lost once hypothyroid people are treated with the synthetic thyroid hormone levothyroxine, but the limited evidence that is available indicates that not everyone loses weight with treatment and in the ones who do, it's limited.