Are you over weight?
Are you putting up more fat?
Is your new year's resolution is to loose some weight?
Wondering how much weight you should loose?
BMI itself is not a diagnostic tool. If your BMI is higher than 24.99, you have a higher tendency to have health risks associated with obesity. So in that case a doctor needs to check up whether you really have any health risks & to check whether you should lose weight.
Read further on BMI:
Wikipedia: Body mass index
CDC: About BMI for Adults
Read further on, Controlling Your Weight