Here are a few general 'rules' regarding calorie intake: Women: should consume at least 1,200 calories a day, or 1,000 less than your maintenance calories (maintenance value = how many calories you need to maintain your current weight). The Harris-Benedict formula is one of the leading ways to calculate your maintenance value.
Men: should consume at least 1,800 calories per day, or 1,000 less than your maintenance calories.
The Harris-Benedict Formula
The Harris Benedict Equation is a formula which will help you determine your BMI. I have provided a link for you to follow so that you can determine your BMI, BMR and the total number of calories you can consume every day. Please check out this resource because it will provide you with valuable information.
http://www.bmi-calculator.net/bmr-calculator
I hope you followed the link and determined how many calories you can consume each day. This is an important starting point that will allow you to determine the foods to eat and how much you can eat.
Many people are attracted to crash diets. Crash diets, where you are only consuming 1,000 calories or less per day, are attractive to people because with a crash diet you can lose significant weight over a very short period of time. The problem with crash diets is your body will not function, over the long term, with this limited caloric intake. As a result of the reduced consumption of calories your body will begin to consume the lean muscle mass and as I discussed earlier your muscles play an integral role in the burning of calories. With a crash diet you will lose weight but damage your body in the process. The other problem is that you cannot remain on a crash diet for very long and as soon as you stop the diet you will gain back all the weight and probably add a few pounds.
In summary crash diets do not work and are unhealthy because:
Starving your body will not provide you with long term weight loss.
You need your muscles and a crash diet will decrease the amount of lean muscle mass within your body making it even more difficult for you to lose weight in the future.
Your metabolism needs fuel to operate effectively and when you eat less it will slow down your metabolism. You must provide your body with fuel at regular intervals to allow your metabolism to be at a high level.