My pet theory? We all see ourselves as an idealized version of ourselves that was set a long time ago.
In my case, I was well past the "obese" point on the BMI scale, but not "morbidly obese" yet. I thought I was overweight, but not badly so.
Then I stopped and took a good look at my BMI and where it should be, and decided to diet. I lost some weight myself, and then went to a doctor who prescribed a drug to help me. I ended up losing almost 70 lbs. I've gained about 20 of that back now, but I've been holding (or slowly slipping) for quite a few years now, and still want to lose again.
I look at old pictures of myself and I'm horrified at how fat I was. But at the time, I didn't see a problem.
