http://www.bbc.co.uk/news/technology-31113602TBH, a lot of what you get from an activity monitor, is bollocks.
For a start, it can't ever know how many calories you are burning. The only way to determine this is by living inside a metabolic chamber, or briefly on a VO2/VCO2 test, wearing a mask and having your breath analysed. So ignore anything that tries to predict the calories you're burning. For the record, although I monitor my food/activity (I use MFP), it's only to keep an eye on macros - I pretty much ignore calories.
Secondly - I ignore the "distance" measurement my FitBit gives me. I've given it an approximate stride side - but it's going to be so approximate, not to mention variable, that it's probably rubbish. It's definitely rubbish when cycling - I'll record something like 35,000-40,000 "steps" when riding a 200, so the web app gives me 35-40km of distance.
What activity monitors do is measure movement, and you can keep a record of this and use it to compare one day against another - and for that they're pretty handy. Also, movement/activity at night can be approximated to sleep quality.
I find if you work within those parameters, and apply some interpretation, it's fine.