Is It Normal to Gain Twenty Pounds in the First Trimester?

Patient: I am currently seven weeks pregnant. So far I have gained a total of twenty (20) pounds. I was diagnosed with hyperthyroidism two years ago. My normal weight is between 110 and 115. Could my overactive thyroid have anything to do with my twenty pound weight gain? Is this much weight normal in early pregnancy?

Symptoms: Substantial weight gain