http://www.medications.com/effect/view/23994 My daughter (now 18) was diagnosed with Hashi's 2 1/2 years ago. She had headaches, was tired more than usual and irregular periods. Now on synthroid for 2 1/2 years, she has steadily gained over 35 lbs. She works out every day and eats ONE meal per day. Fri, 18 Apr 2008 20:05:32 -0400 http://www.medications.com/effect/view/23994?item=7423 First of all, if your daughter is eating only 1 meal per day, this could be the problem. Your body goes into "starvation mode" and starts storing fat if not getting the proper nourishment. Working out and not eating still does not help. http://www.medications.com/effect/view/23994?item=7423