Comments have brightened up an otherwise dull morning. If you don't measure it, you can't measure changes in lifestyle and from my experience I needed a bit of encouragement. So my fitbit transponder lives in my pocket, not on my wrist - so the accelerometer cannot measure chopping carrots. But does show me how much or little I have moved in my sedentary job..and for how long. We aren't designed to sit all day.
It ONLY has ANY value if you watch what you eat - not necessarily calorie counting, just sensible eating, AND NO SNACKS, deep fried Mars bars or other culinary delights that are heart attacks on a plate.
I have never bothered taking a scrap of notice of the 'calories burned', and the Chemists rough counter is much more use - two miles walking = 200cals, plus the height gained, plus a bit more for being 10kg heavier.
Simples really, eat less, more healthily, more exercise, live longer.