I recently checked out my
BMI (body mass index). It is the ratio of your height, to your weight squared. It is a general indicator that can help tell if your overweight or underweight. The drawback is, it is only a number that does not know the difference between fat and muscle (we all have a lot of muscle, right?). But I think it is a useful indicator, and would only be un-useful if you had a weird sport like weight lifting with the muscles to match.
On some charts, "normal" is 18.5 to 25. 25 to 30 is overweight. Last week I was 26, which is overweight. But with some training I now have an index of 25, making me almost normal again. But on some charts, 18.5 to 23 is normal, and over that is overweight. I am aiming for 23.
BMI = 80kg / (1.755m)^2 = 25.9