Also keep in mind the "trickiness" of the calculations. I'm not sure how TDP or FitDay work, but you've got to remember to also take into account the amount of calories that your body would have burned naturally had you spent the 30 minutes you worked out simply sitting on your butt in front of the tv. For example, say you burn 250 calories walking for 30 minutes. But, your resting metabolic rate says that you would have burned 60 calories anyways by basically doing nothing. So, in total, you've got a net number of "extra" burned calories of 190, not 250.
Lots of math makes my head hurt ... another good reason not to worry about it.
