One pound.  Have you ever stopped to think about it?  One pound is equal to 3500 calories.  Want to lose one pound?  You have to somehow have a negative of 3500 calories in your “calories spent” tank.  Losing one pound in a week should be easy, right?  Sure!  Just cut out 500 calories from your diet.  Every day.  For a week.  Then keep it up to keep it off.
     Now let me take you into the science and mathematics of losing one pound.  First, you need to know your BMR (Basal Metabolic Rate), the number of calories your body burns just living, breathing, functioning.  Go to http://www.bmi-calculator.net/bmr-calculator/ and plug in your numbers to get yours.  My BMR is 1360.  That means, in order to maintain my current weight, I must eat 1360 calories.  If I want to lose weight, I need to eat less than that.  Our lowest amount of calories we should consume are 1200 calories in a day.  In reality, I should only cut my calories down 160 a day for weight loss.  If I were to just cut calories at 160 per day, it would take me 22 days to lose ONE POUND.  I could speed that weight loss up by adding exercise.  If I was trying to lose that one pound in one weeks time, that would mean I would need to burn an extra 340 calories a day.  For me, that’s about a 3.5 mile run at a 10 minute per mile pace for a total of 35 minutes.  Oh, and don’t forget that I must only be consuming 1200 calories. If I go over 1200 calories, I have to workout even more!  If I cheat and have a Grande White Chocolate Mocha Non-Fat No Whip for 350 calories, that’s an extra 35 minutes of running for me.
     Figure out your BMR and know that number by heart.  Then, keep a food diary for a few days to see what your caloric intake is.  From there, you can figure out what you need to do in order to lose, gain, or maintain your weight.