I agree with Lori, none of us (well, most of us, as far as I know) are not medical professionals, and the advice we give is based on our own research and experience.
That being said. This is copy/pasted directly from the FAQ in the Calorie Counters forum.
Quote:
How many calories should I be eating?
There is no set number that is perfect for everyone. Everyone's calorie needs are different, and while there are many online calorie calculators out there, they are really just guestimates. The only real way to know how many calories to eat per day is through trial and error. Basically, you have to find out what works for YOU.
Here are some factors that will play into your caloric needs:
How much you exercise: Calorie counting is all about taking in less calories than you burn each day, so someone who exercises regularly is going to be able to eat more calories than someone of the same body size who doesn't. Someone who walks 5 miles a day is going to burn more calories than someone who walks 1 mile.
How active you are in everyday life: A waitress, aerobics instructor, or a construction worker is going to have a more physically demanding job than someone who sits at a desk and computer all day. This will affect your calorie needs.
How much you weigh: The more you weigh, the more calories you use per day. Think about it-if a 250 pound woman, and a 150 pound woman walk a mile together, the woman carrying 100 extra pounds of resistance with her is having to work much harder-and this is true walking stairs, and doing all of the everyday activities. So, your starting weight will have a lot to do with your starting calorie level.
Here is a good starting guide for you to begin self testing your personal calorie needs:
Over 300 pounds: Start at around 2000 calories a day.
Over 200 pounds: Start at around 1800 calories a day.
151-199 pounds: Start at around 1600 per day.
150 pounds or less: Start at around 1500 a day.
To find out your personal calorie level for weight loss, you simply find your starting point, and weigh in. Try the calorie level above for a week, and weigh in again. If you have weight loss of 1-3 pounds, then you are on the right track. If you show no loss at all, then drop it down by 100 calories a day, and see what happens the next week. On the other hand, if you show a huge loss-then you would probably be better off adding 100 calories a day to that level. And so on and so forth...
As you lose weight, your calorie needs will change. You might lose just fine for the first 2 months at 1600 calories a day. 20 pounds down the path, the weight loss stops. You don't lose anything for a couple of weeks. This is when it is time to go to the next level. Drop your calories down by 100 to 1500 to get things moving again.
So, 1800 is probably a good starting point. If it were me, I'd stick to 1800cal for a week (you can zig zag also...1800, 1600, 2000, 1800, 1700, 1900, 1800...all those average out to 1800 for the week). If you have a satisfactory loss, keep going with it, no need to fix what isn't broken. If you have no loss, try upping your exercise and lowering your your calorie limit to 1700 for a week and see if that helps.
Keep in mind, that your calorie needs will change over time. When I started at 183, I absolutely never exercised more than walking to class, and I ate 1400-1800. That worked great for several months until I plateaued at 150. I now exercise several hours a week and eat between 1200-1500 and weight loss is still slower.