Mm mm. Cheese.
I have a Fitbit charge. I bought a 'one' last August but didn't really do much with it, just used it to track what I was doing iyswim, but at Christmas I decided to buy dh and I matching Fitbit charges and an Aria scale as his Christmas present (I did get him something else as well lol). SIL and the ILs were visiting over Christmas too. SIL is desperately overweight (and hey, I'm no skinny minnie having 3 stone to lose) and was quite despondent, but we had talked about a few things, and motivation and stuff, and on impulse I went out last thing on Christmas Eve and bought her one as well. Dh was terrified that I was about to start WWIII - but of course he didn't know that he was getting one as well bahahaha.
Anyway, SIL was chuffed, and so since Chrismtas we have been in a little Fitbit group, challenging each other most weeks, and she is finding it pretty motivating and the weight is slowly coming off.
I really only use mine for steps and to monitor my sleep (which is shocking) but if I could be bothered I could use it to calorie count and whatnot as well. I know some people use it to track water intake too.
They are very clever. I know I am not using mine to the full extend, but I am still pleased that they are working out for the purpose I bought them. I often find myself walking about to reach my step goal instead of vegetating on the sofa. And of course, that means I am not sitting eating cheese and crackers 
We have the highest percentage of Olympians per capita in our wee town than anywhere else in the world. True dat. It is BONKERS here. They keep going into the schools and parading their medals and the kids just eye roll. Another one? But all the kids are hardcore athletes and swimming or playing(ice) hockey at 5am before school, or spending the weekends ski racing. Fortunately, we moved her way too late for mine to get properly involved, although dd2 (dc3) is going to her first para ski race in two weeks 
Being fat here is something of a novelty, anyway... There aren't many of us around... 