How does Fitbit calculate the calories burned? Does it use a fixed equation, like Mets, or does it calculate it based on heart rate? I've been involved in bodybuilding for years and have always calculated my daily calorie requirements on my own and had a lot of success in both gaining and losing weight. After using the Fitbit weight lifting activity, I was surprised to see my calories burned was about 600 calories higher than I would have expected. I checked treadmill activity and elliptical activity and both of those were what I expected them to be and also where close to what the machines said they were. For the past week I have not started the weight lifting activity before I lifted to see how it affected things. The Fitbit registered the workout time under activity, but my daily calories burned are between 400-1000 calories lower than the previous week doing the same workouts. If Fitbit was calculating calories burned based on heart rate, the numbers should be a lot closer.
