I bet you can guess that it is to lose weight.
I believe that the body has an ideal weight and when you are in that ideal weight zone, it is easier to stay at that weight. I also believe there is a comfort weight level your body can reach above that ideal weight zone and it is really difficult to get under that comfort weight level.
Most everyone is obsessed with their weight for one because it is an easily attained statistic. Step on a scale and boom. There it is. But there are other measures of health. Such as body fat percentage. According to the internet, my source of almost all knowledge these days, says that a fit percentage of fat content is 21-24% for women and 14-17% for men. An average percentage of fat content is 25-31% for women and 18-24% for men. Where do you fit?