exercise cals, HR monitors, fitbit, bodyfat, oh my!

thrillho3

I have a few questions.

I'm following the TDEE - 20% method to lose weight. I calculated my TDEE from various websites (I put "lightly active" as I bike about 40 min 4x/wk and play tennis on the weekends) and used an average from my FitBit (consistently gives me around 2100 cals/day). So, I'm eating 1600 cals/day to be on the "safe" side.

People on MFP tell me that since I'm following this method, I shouldn't eat back my exercise calories, because it was already calculated in the "light activity" portion.

First of all, if I shouldn't eat them back, what's the point of logging them into MFP? It winds up just confusing me.

Second of all, do I need a HR monitor to accurately calculate my exercise calories? MFP says in 20 min of biking I burn 190 cals, but people have said that's a huge overestimate, and it's more like 120 cals. I'm 5'5", 207, female, 30yrs old, and according to various sites, my body fat is like 44% (almost half my body is fat? Christ). I don't know if this matters into the calculation or not, but the way I am built is pretty muscular as-is (especially my legs), so perhaps I'm not *quite* half fat?? :embarassed:

Any help/advice appreciated, thanks :flowerforyou: