How much exercise would I need to do Per day if I am 165 pounds, want to keep eating the same amount of calories but?

Want to weigh 57kg. I am not seeking to reduce what I am eating but may change the amount of protein ( an increase). I hope to be at 57 kg by December 2016.

thank you
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+1 y
Had an epiphany last night (1 am to be exact). Decided to get rid of our storage of 'goodies' and handed them to old work colleagues today. It was a total of 54L of potato chips, chocolate, gourmet popcorn, popchips, plaintain chips, biscuits and chewy candies. Surprising to say but felt relieved to rid of them. They had been accumulating overtime and I was eating little quantities over time. Guess it makes sense why I was gaining weight! Ha! Thank you all for your insights!
How much exercise would I need to do Per day if I am 165 pounds, want to keep eating the same amount of calories but?
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