Experiment!!

Okay guys,
I just had a strange idea & I will make an experiment of that!

The last time (exactly 1 yr ago) I wanted to lose the usual weight that I gained over christmas, so I reduced my daily calories from 1500 to 1000 pd for a month. Worked all fine, lost more than I wanted, was happy! (Haven't done any sport in that time.)
Means I "burned" 500cal pd and 15.000cal in that month.
Now, it's nearly all the same. Still walking around with christmas food in me or rather on me BUT now I have this little hometrainer here and that brings me to my experiment. I have this computer which tells me how many kilometer I ride and how many calories have been burned in what time. I don't really trust the calorie counter but I guess it can be used as a guidance.
When I do a lame workout, means cycling for at least 40mins (the length of a Desperate Housewives episode ;);) ) with every now and then a short time of using the step machine (it's a 2in1 thingy) I have 17-18km / 11miles and according to the counter about 1000-1200calories burned. (Always depends on the resistance-level (can I say that?))
My last normal workout counted 1900 calories after 70mins. And this is what brings me to the idea of my experiment.
If I do a big workout every day for a week, means burning 2500-3000 calories pd on the hometrainer, shouldn't I lose as much as I once did in 1 month? That were about 8kg/18lbs
Is that even possible? Sounds a bit utopistic to me, but I want to try that. Spending about 100mins on the bike every day is not a big thing for me. When worse comes to worse and my stamina is down to nothing I can still split it into 2 workouts a day.
Burning this mass of calories for a week every day would make a result of 17500-21000. That's even more.
If that's really working, WeightWatchers can quit. ;) ;)

For the record: I intentionally didn't include the normal 1500 calories that girls burn every day because I have to eat something, hu? And I guess I will need them. No energy, no sport.

Oh and additionally of course the small workout/s with free weighs, stretching and stuff. Don't know if that burns many calories.

However, will try that tomorrow for a week.
Wish me luck!!