Why do I feel foggy if I only eat 800 calories a day?

Why do I feel foggy if I only eat 800 calories a day?

1. Actually it is exactly like your starving your self. Both body and mind need more that 800 calories a day to run a day to day life.... this includes brain function and energy levels (this is why you feel foggy)
   All your systems are running on half to save calories for you to keep living... as well as being very damaging to most of your body your also ruining any metabolism you might have had, and as a result you will find it very hard to lose weight or keep weight off in the future (when you start eating like a normal person).
   
2. Your body is in starvation mode. it happens when you eat less than 1200 calories a day. why are you doing this. your body is holding onto fats and will eventually eat muscle. eat more.
   
3. A normal person needs at least 1200 calories in a day. If you eat lesser than this then your body will react differently. Your body has to perform a lot of functions during the day, and if you do not give it the desired quantity, then it will also not help you. Respect your body.