Your Basal Metabolic rate is what your body burns, just by living. If you're in a coma for example, just your brain thinking, controlling your bodily organs takes up 70% of your daily allowance. This means around 1400kcal a day is just used up on just breathing and general living. The rest of the food you take in is just to exercise and be able to get out of bed.
You must eat more than 1100kcal a day. Around 1500 will be much more appropriate.
P.s, this is coming from a recover anorexic! Who used to exercise and cut down to 300kcal a day.
I also have learnt a lot in nutrition. I know these things!