@Brad_Olwin I would guess it’s mainly for loosing weight - at least thats why I bought my first fitbit, counting calories and looking to reach a calorie deficit every day - and it didn’t work (at first) since Fitbit‘s calorie calculation ( and I agree: thats all it is - a calculation, no real measurement) was much too high for my metabolic rate. The only way for me to really find out how much I burn, was to actually track my intake (to get a rough number of calories consumed) and track my weight for some weeks. I then found out how much I could eat without gaining weight and from that number of calories I subtracted about 300 to 500 kcal a day, and did this for some month, loosing 10kg and keeping it. With lower weight there had to be done some adjustments in intake, but I now have a relatively good idea of the number of calories I could eat without gaining weight again.
Actually Suunto‘s estimation of my daily calorie burn was very near that number together with a very cheap Amazefit tracker (and the one on the website of the Mayo clinic ) Polar was way off, as was the Apple watch. I guess there are different algorithms for calculating your bodies calorie consumption regarding your age, weight, etc. and if your device uses the wrong one you will actually never loose weight, but even gain more :-).
