Can someone explain to me how mfp calculates exercise calories? One day I had 8,246 steps and it gave me 750 calories earned. Another day I had 8,302 steps and it gave me 558 calories earned. And then one day I had 9,076 steps and it gave me 639 calories earned. None of this is adding up correctly. I haven't changed any settings or goal weights or activity level. Is anyone else having this problem? How is it corrected?