Honestly. Do they actually help it just a bit of a gimmick.
I have about 3 stone to lose but haven't quite got round to starting yet. 
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Looking for a gadget to track steps, calories, and all that jazz? This thread is a little old. Check out our round-up of Mumsnetters’ favourite fitness trackers for the low-down on Garmin, Fitfbit and some other -cheaper- alternatives. MNHQ.