I am 27 years old. I was on the pill for about 10 years. When I went off, I GAINED 12 lbs almost instantly. My diet and exercise had not changed. I didn't get a period for about 3 months, so I kept waiting for my hormones to normalize. After 6 months of being a size larger than normal, I decided to go back on the pill - nothing has changed so far (after a month). I'm going to an endocrinologist to sort this out, but other than hormonal changes, there is no reason for me to have gained this much weight overnight. Has anyone else experienced this?