Tracking HRM Calories Accurately

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So I was talking to my doctor and I told her how my progress was going. I noted that my progress seemed a little slower than "normal" for me and mentioned that I "eat back" my exercise calories. She said that this is good, because I need to keep an eye on my net calories. SO, I then mentioned that I kept track of my calories with my HRM and I told her that is the amount that I eat back.

THEN she said something that makes perfect sense. Eating back ALL of the calories my HRM reads is actually a false reading simply because-in the time that I was exercising, if I had been sitting on my *kitten* doing nothing, I would have burned 100 calories regardless (maintenance weight/24 hours in a day=100 calories/hour hence, 24*100=my maintenance weight is 2400 at this weight).

So if I work out for 30 minutes and burn 290 calories, I really should only record and eat back 240 calories. Which will prevent me from having something like 150 calories over my weekly allowance.

Just wanted to share for anyone that may be frustrated out there. Happy Friday!