BrainyChick
I was a VERY thin child until age 9 or 10. I gained some weight, but was by no means obese. I maintained a reasonable weight until after the birth of my only child. At that time, my body did some pretty strange things that resulted in the atrophy of my thyroid and ovaries - which threw me into premature menopause (at age 22).
Once my thyroid tanked out, I gained about 75 lbs in one year. From then on, I struggled with my weight - eventually ballooning above 250. I had EXTREMELY high blood pressure, severe depression and was borderline diabetic. Thanks to this wonderful gift - I can thankfully say that I am in perfect health now. 
