One pound is equal to 3500 calories.
Simply and mathematically speaking, you would need to have roughly negative 1500 calories between diet and exercise each day to acomplish this.
So, if you need 1800 calories each day
A little about my 'heavy' history...
I've had weight issues the majority of my life, pretty... birth to Cassie, I found myself only 12 lbs. from my pre-pregnancy weight. Wonderful!!!!