I think the 'step counting' function is fairly poor at helping weight loss. In fact, I consider the counter on mine to be very inaccurate even with calibration.

However, it has been a great tool for my weight loss journey and I've lost 50+ pounds. Where I've found my fitness tracker useful is in the fact it monitors my pulse rate throughout the day. I use it to make sure I keep my heart rate in-the-zone, so to speak.

So, no fitness trackers are not a silver bullet for weight loss, but, they can help. If they are used properly and with dedication.