Caroline271 is correct. But to address your question. Weight training is aimed at building body mass. However in my opinion, weight training is the lease optimal way to burn calories. I think you will find that cardio-vascular training (fast walking,running,fast biking,swimming etc) is the best way to lose weight. The secret is to keep your heart rate in the "training zone". You can find instructions via Google as to how to take your heart rate and what the pulse rate should be for different ages. Therefore, since most warm ups will not get your pulse rate up to your training zone, they shouldn't count. This training zone counts for any activity. Until your pulse rate is maintained it for the time allotted, it is not doing much for you.
The Perfect Speed
"any number is a limit, and perfection doesn't have limits.
Perfect speed, my son, is being there.”
Chiang from "Jonathan Livingston Seagull