i have been readinp posts from people who are conscious about their weight and want to become slimmer and i have this to contribute:
it is important to know if one is underweight, normal weight, overweight or obese before deciding one wants to lose weight.
there is a simple index called the body mass index, bmi. it measures the relationship between the weight and height of a person to determine the nutritional status of an individual.

i am attaching a software to this post, so that everybody can make use of this to know what category they fall into.

its simple to use, all u need to do is know your weight and your height and insert it in the appropraite space. the software will interprete the result for you.

choose the correct and same unit for weight and height. that is, if you are using imperial, then your weight must be in measured in pounds and your height in feet and inches.
if you are using metric measurements, then your weight should be in kilograms and your height in centimeters.

Here is an online calculator:

http://www.halls.md/body-mass-index/bmi.htm