Hi, I was recently diagnosed with hypothyroid and put on levothyroxine 12.5mg or half of a 25mg tablet. I have been on it for 3 weeks now and have gained 7 pounds. I have always been very thin 110 pounds ate whatever I wanted when I wanted for more than 30 years and it has only been since starting this medication to speed up my thyroid now that it is hypo that I've gained weight. This seems backwards. I did not gain a pound while I was unknowingly hypo before diagnosis but now that I have been on meds to correct it I am gaining weight. Why is this and what can I do to stop this weight gain? thanks