Can hypothyroidism lead to fat gain?
Yes, a less active thyroid will reduce metabolic rate and can cause some weight gain. It is not a lot of weight gain though, and a subactive thyroid is not an excuse for obesity (if hypothyroidic, please see a doctor for medication; it burns fat)
A little. Thyroid problems play a negligible role in obesity.
The American Thyroid Association states:
In general, 5-10 pounds of body weight may be attributable to the thyroid, depending on the severity of the hypothyroidism.
Most of the weight gain directly associated with thyroid issues is negligible. In fact, the average weight loss from treatment was 4.3kg, most of which was attributed to the excretion of excess body water
Pre-existing obesity, a diagnosis of Graves' disease and prior weight loss independently predicted weight gain and weight continued to rise with time.