well.... here's how it works.first off though i don't know your stats so i don't know if you actually have any weight to lose, but either way... if you do, or if you just want to see better results from training while already at a sensible weight... the same applies.
BMR is how much your body requires just to function without so much as rolling over in bed all day. So, cell regeneration, keeping your heart beating, bone and muscle and organ maintenance, skin and hair and fingernail growth.... god I don't even know, all sorts of other stuff that's required to be alive.
And right now, eating below BMR means you're not even giving yourself enough fuel for that - let alone to build the lean & toned figure I imagine you probably want. Or even just to move around a bit during the day. So what that means is your body has to find a way to compensate and survive on so much less fuel that it really needs. It manages this through hormonal changes.... thyroid shuts down, adrenal glands pump out more cortisol.... in simpler terms though your body is trying to conserve and store energy because it thinks "i'm not getting enough, if i run out of what I have stored in reserve i'm fucked". So in other words your body wants to store fat and it will sacrifice muscle and bone mass to do this. Very bad stuff.
So screw doing that. If you really want to create the body you really want, you need to dial in a plan that provides enough fuel not just to replace what you burn just by being alive + moving around a bit + exercise... you need to put in enough to actually be able to adapt to training. That would mean storing more energy in the muscles, strengthening your bones with increased density, more lean, toned muscle mass.... if we get it right your body goes "well bloody hell I only JUST have enough resources available to manage all this... these fat stores can GO I have other priorities right now"
Makes sense?
So... we can dial in appropriate calories to support an appropriate weight, put all of that fuel to good use... and end up healthy, strong, sexy and happy. I have girls who are eating seriously over 1000 cals a day more now than they were when they first came to me for advice and they are so much happier with their results and just in general because of it, eating all the nice stuff whatever they fancy!
So that was a long answer but in short "yes you need to eat more than your bmr and you'll be much happier with your results if you do".
