When I was significantly overweight, I ate many days under my BMR, but my average consumption was right around my BMR. As I got smaller and my BMR dropped, the days that I ate under my BMR got fewer and fewer. It wasn't a calculated thing, I just got hungrier. My macros have been all over the place, but often they seem to fall into 40f/40c/20p.
I am not aware of any scientific evidence that chronically eating under your BMR will lower it. I believe there is some evidence that eating *way* under (<1000 cals/day) will temporarily drop it on the order of 100-200 cals /day. All the advice around BMR and calories is speculation and conjecture. It's probably not possible to give general advice because there's a huge variety in the way different people's bodies mobilize excess body fat. Personally, I found consistently eating as little as possible without making myself miserable to be extremely effective. I had no other "rules" regarding my food and eating.
ETA: eKatherine makes a good point. A lot of extra body fat will artificially elevate your calculated BMR. It makes using BMR as a guide even trickier.
Last edited by LauraSB; 03-23-2013 at 06:10 AM.
CW-125, part calorie counting, part transition to primal
GW- Goals are no longer weight-related