If "resting calories" are the calories I would have burned if I were resting instead of engaging in that particular activity, I have bumped into an additional issue.
I walked for 2 miles first thing this morning. WahooFitness reported a caloric burn of 253 calories and the Fitness App reports 187 "Active calories." The mystery deepens here as the "Resting calories" are listed at a whopping 1,220 and total calories for the activity are reported as 1,408. Clearly, I wouldn't have burned 1,220 calories sitting on the couch for 30 minutes.
If trbeals suggestion is correct, why on earth would Apple feel we need to know calories we would have burned during inactivity? Additionally, how could they possibly calculate my resting metabolic rate accurately? I can whip up an algorithm that puts me a heck of a lot closer to predicting caloric burn during my bike rides than what the Watch is reporting here. The physics of movement is relatively easy to calculate, but determining an individual's resting metabolic rate without knowing their body composition borders on voodoo science at best.
I appreciate rowanmcdonald1991 suggestion of pairing with a chest strap, but doesn't this completely defeat the purpose of using the watch as an activity monitor? I have been using the Alpha Mio as my heart rate sensor, but the Apple Watch doesn't make the connection to the watch. My iPhone syncs to the Alpha Mio and both WahooFitness and RideWithGPS connect to it without issue. The Apple Watch doesn't even see the Mio in the Bluetooth settings connection screen. But, really, the last thing I want to be doing is having to use an additional watch to properly record my heart rate during intense exercise!
I've been wearing both the Apple Watch and the Alpha Mio to compare reported heart rates, and have been pleasantly surprised to see there is very little variation between the two.
I suspect there are simply some issues with the algorithms that Apple is using to calculate our caloric burn rates and hopefully, they'll improve upon them soon enough. Having used Strava, Digifit, RideWithGPS and Wahoo, I've seen them all quickly improve their calculations over time.