How do i know if i am overweight?

Overweight: It has its flaws but to my knowledge the gold standard measurement out there right now is the BMI (Body Mass Index). Using this chart can help you determine if you are overweight or not. In my opinion it doesn't account for muscle mass very well. Ultimately, it's using the chart and discussing your results with your PCP.

BMI is a crude guide: The bmi formula, english units, is (wt in lbs) x 703÷(ht in inches), see: http://en.Wikipedia.Org/wiki/body_mass_index. Optimal just below 20 to ~25 bmi range. However, if very muscular, bmi overestimates body fat. The bigger issue, healthwise, is body fat, which is driven by low-fat diet/foods (carb/sugar is rapidly converted to triglyceride fats, by liver ; stored). See nusi.Org, fatchance.Html.