Opinions on accuracy of Fitbit calorie count

[slimtrade]

Hi, I’m wondering what others thoughts are on the calorie counting. I believe that it’s counting a bit high. Is this a known issue?

[Baltoscott]

High @slimtrade It's high for some people, and about right for others. That said, I think it accurately reflect whether you or burning more or less from week to week. So, when I'm trying to lose weight, for example, I try to focus on burning a bit more than normal. Though the other side of the equation, consuming few calories, seems more effective. 

[t.parker]

@slimtrade you can't speak of accuracy for the metric that nobody has a ground-truth reference for. It's an estimate and as with any estimate, it may or may not be closer to reality.

Fitbit uses mostly HR to estimate calories (with the exception of swimming. The best (most consistent) estimate would be for steady-state activities (like easy/endurance running/cycling). It's because the HR is elevated during a prolonged period of work (in a physics sense) that your body does in order to move forward. However, the activities like weight lifting (with short bursts of work and then longer resting periods) will most likely be inflated as your heart slows down gradually while resting. You stop performing exercise immediately after the last rep (no work, no energy expenditure) yet your HR stays elevated for a short while. Also, it's important to know whether the watch tracks your HR with accuracy (unlike calories, HR can be easily verified against equipment like chest straps). Bad accuracy defeats the purpose of any HR-based metric. You need to find a way of interpreting calories for your individual needs. It's not a metric that can be accurate but I agree with @Baltoscott that you can make it work for you by observing certain trends.