800 a day and you'd be damaging your health, possibly forver. It puts a massive strain on your heart and immune system. No point being skinny and dead, although, coffins are cheaper....
Your body would think it was in a famine and retain as much fat as possible. Your metabolism would virtually stop.

What you're doing is good, keep that up.

*gets out short skirt and pom poms and does a little cheer for Sybs*