it does adjust, how much depends on what you are doing with it
when you have your computer off...... it will draw like 1-2 watts from the outlet
when you have the computer on, idling (no programs running, and not doing anything) it will draw X amount of watts from the outlet
X is the minimum amount of power it needs to stay on
like a car consumes gas even when it's in park
when you are just web surfing, it'll draw a little more than X
like a car cruising on the highway
when you are doing intensive stuff, like play a video game, transcoding a video
it'll draw a lot more than X
like when you floor the gas pedal
for example,
idle: 185 watt
browsing: 200 watt
playing video game: 330 watt