If you wish to lose weight with the help of a fitness tracker, then try to wear it regularly.
Which means you need to wear it even on your lazy days, off days, and even those days when you are not doing your exercise.
Those off days need to be accounted the most, and in such cases the best fitness tracker with heart rate monitor will be your perfect buddy.
Why do days off matter a lot? If you want to collect information only on days when you are active, you will never see the obstacles in your weight loss regime.
Consistency is the most important thing when you are trying to lose weight.