Just a quick-hit tidbit here.
The Microsoft Band uses a number of sensors and your profile information to create your personal calculation for calories burned during activities and throughout the day. Specifically, it uses the built-in movement sensors, the heart rate monitor, and your profile information (height, weight, age, and gender) to estimate your calories burned. So, it’s essential to enter your profile information correctly.
But, what if you’re not wearing your Band? Or, just have it charging while taking a shower or other non-active moments?
The Band still works to estimate your calorie burn even if you’re not wearing it. Just like how the Band gets more accurate over time when you feed it run data, the more you wear the Band the better it gets at estimated the true value of rest information. Essentially, if your heart rate is not being recorded, the Band calculates the number of calories that you burn based on the assumption that you are at rest. This calculation uses numbers from your profile such as sex, height, and weight. For better accuracy, make sure to take advantage of the feature to change your weight. Ensuring your weight is accurate also ensures that the Band's calorie output for resting is as optimum as possible.
If your calorie burn goes nuts, is either too low or too high, double-check that you’re wearing the Band tight enough or that the Heart Rate sensor is working. If you’re constantly seeing abnormal spikes in recorded data, it’s probably a good indicator that something might be amiss with the Band’s Heart Rate monitor and you should contact support to verify.