To stay at a healthy weight, you need to balance the calories you eat with the calories you burn (use up). To lose weight, you need to use more calories than you eat. A healthy diet and physical activity can help you control your weight.
Calories are a measure of the energy in the foods you eat. You burn calories when you are physically active.
How do I know if I’m eating the right number of calories?
 This is the number of calories you need to maintain your current weight. If you are overweight or obese, burn more calories than you eat to lose weight.
Finding out your body mass index (BMI) is the best way to learn if you are at a healthy weight. Enter your height and weight into this Body Mass Index (BMI) calculator to find out your BMI number and what it means for you.
If you are already at a healthy weight, continue to get regular activity and choose healthy foods.
Set realistic goals.
Start out by setting small goals such as:
•    I want to lose 1 to 2 pounds a week.
•    I will add 10 minutes of physical activity to my daily routine.
•    I will avoid second helpings for one week.
Adult BMI Calculator: English/Metric
This calculator provides BMI and the corresponding BMI weight status category. Use this calculator for adults, 20 years old and older. For children and teens, 2 through 19 years old, use the  BMI Calculator for Children and Teens.
For further detail, please go the following link: http://www.healthfinder.gov/prevention/ViewTopic.aspx?topicID=25