from 18 jan through 30 jan i ate 32,540 cals and burned 40,352 according to fitday. that would give me a 7812 cal deficit, or 2.2 lbs according to their 3500 cal per pound estimate. according to my bathroom scale i dropped 2 lbs.
so far then, fitday seems to be right on with my input vs. output. i run, and the calories it lists for my runs seem to be about 30% higher than what i get from my heart-rate monitor (hrm says about 80 cals/mi, fitday about 110).
it's just one data point so far, and i'll know more in another two - three weeks. but since the calculator here seems to make sense, i'm inspired to keep using it now.
almost hit 5000 cals burned yesterday, with a 10mi run and 8mi hike... no wonder i slept 11 hours!