Your thyroid affects every single cell in your body. It makes sense, then, that a thyroid disorder can greatly disrupt your daily life. Hypothyroidism is the most common thyroid disorder. It can lead to muscle weakness, sensitivity to cold, impaired memory, weight gain, and so much more. One type of hypothyroidism is called “permanent hypothyroidism” — most doctors will prescribe drugs for the rest of your life, laden with side effects.